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Ultrastructural changes and visual symptoms resulting from nutritional disorders involving boron, manganese, iron, zinc, copper, molybdenum, and nickel depend on the species of the plant, and are unknown in passion fruit plants (Passiflora edulis Sims). A hydroponic experiment evaluated the symptoms of nickel addition and micronutrient deficiency in passion fruit seedlings "BRS Gigante Amarelo" and determined the micronutrient contents in leaf and root tissue, root development, ultrastructural changes (leaf tissue deformations) and dry matter accumulation when visual symptoms were observed. Results showed that the order of manifestation of deficiencies was Fe > Mn > Zn > Cu > Mo > B. Nickel toxicity appeared 40 days after the experiment was started, presenting chlorosis in the new leaves followed by general yellowing and some white parts. Boron omission of resulted in deformations in the leaf limbus and loss of apical dominance, showing deformation of the growth points. Mn omission caused reduction of growth and generalized chlorosis of young leaves with a thick reticulum. Iron omission of resulted in internerval chlorosis with a fine lattice appearance. Omission of zinc and copper resulted in deformation and elongation of the leaves, reducing height and root development. Molybdenum omission caused chlorosis in the older leaves, which was observed to spread over time. Iron was the nutrient that most reflected symptoms of deficiency by the formation of root hairs. The findings of this research suggest that the knowledgement of plant micronutrients status permits an understanding of the physiological responses of passion fruit plants to crop fertilization. [ABSTRACT FROM AUTHOR]

Based on the totipotency and pluripotency of cells, plants are endowed with strong regenerative abilities. Light is a critical environmental factor influencing plant growth and development, playing an important role in plant regeneration. In this article, we provide a detailed summary of recent advances in understanding the effects of light on plant regeneration, with a focus on the fundamental processes and mechanisms involved in de novo shoot regeneration, somatic embryogenesis, and adventitious root formation. We focus on summarizing the effects of light intensity, light spectra, and photoperiod on these regeneration processes. Additionally, we propose the molecular mechanisms and regulatory networks underlying light-mediated plant regeneration. This article aims to deepen our understanding of the role of light in plant regeneration and to pave the way for future research on light-regulated regenerative processes in plants. [ABSTRACT FROM AUTHOR]

Ethylene is a plant hormone involved in many aspects of plant growth and development as well as responses to stress. The role of ethylene in plant-microbe interactions has been explored from the perspective of plants. However, only a small number of studies have examined the role of ethylene in microbes. We demonstrated that Azospirillum brasilense contains a functional ethylene receptor that we call Azospirillum Ethylene Response1 (AzoEtr1) after the nomenclature used in plants. AzoEtr1 directly binds ethylene with high affinity. Treating cells with ethylene or disrupting the receptor reduces biofilm formation and colonization of plant root surfaces. Additionally, RNA sequencing and untargeted metabolomics showed that ethylene causes wide-spread metabolic changes that affect carbon and nitrogen metabolism. One result is the accumulation of poly-hydroxybutyrate. Our data suggests a model in which ethylene from host plants alters the density of colonization by A. brasilense and re-wires its metabolism, suggesting that the bacterium implements an adaptation program upon sensing ethylene. These data provide potential new targets to regulate beneficial plant-microbe interactions. Author summary: Food production is becoming a major concern because of reduced arable land from an increased human population and climate change. Application of beneficial microbes to plants is being explored to increase crop productivity. However, this approach often underperforms in field conditions. To better sustain beneficial plant-microbe associations, we must understand what controls the formation and maintenance of these associations. Azospirillum brasilense is a soil bacterium that associates with plant roots and is used as a bioinoculant to boost plant growth and stress tolerance. We provide evidence that A. brasilense contains a functional receptor for the gaseous plant hormone ethylene. Application of ethylene regulates biofilm formation and root colonization of several plant hosts by A. brasilense. Additionally, ethylene causes wide-spread metabolic changes in A. brasilense. This is the first study to demonstrate that a beneficial soil bacterium contains a functional ethylene receptor. These findings suggest that ethylene may act as a cross-kingdom signaling molecule from plants to bacteria that contain these ethylene receptors thereby identifying a potential target to potentially improve beneficial plant-microbe interactions. [ABSTRACT FROM AUTHOR]

Enhancing drought resistance through the manipulation of root system architecture (RSA) in crops represents a crucial strategy for addressing food insecurity challenges. Abscisic acid (ABA) plays important roles in drought tolerance; yet, its molecular mechanisms in regulating RSA, especially in cereal crops, remain unclear. In this study, we report a new mechanism whereby ABA mediates local auxin biosynthesis to regulate root gravitropic response, thereby controlling the alteration of RSA in response to drought in cereal crops. Under drought conditions, wild-type (WT) plants displayed a steep root angle compared with normal conditions, while ABA biosynthetic mutants (mhz4 , mhz5 , osaba1 , and osaba2) showed a significantly shallower crown root angle. Gravitropic assays revealed that ABA biosynthetic mutants have reduced gravitropic responses compared with WT plants. Hormone profiling analysis indicated that the mhz5 mutant has reduced auxin levels in root tips, and exogenous auxin (naphthaleneacetic acid [NAA]) application restored its root gravitropic defects. Consistently, auxin reporter analysis in mhz5 showed a reduced auxin gradient formation in root epidermis during gravitropic bending response compared with WT plants. Furthermore, NAA, rather than ABA, was able to rescue the compromised gravitropic response in the auxin biosynthetic mutant mhz10-1 / tryptophan amino transferase2 (ostar2). Additionally, the maize ABA biosynthetic mutant viviparous5 (vp5) also showed gravitropic defects and a shallower seminal root angle than WT plants, which were restored by external auxin treatment. Collectively, we suggest that ABA-induced auxin synthesis governs the root gravitropic machinery, thereby influencing root angle in rice, maize, and possibly other cereal crops. [Display omitted] • Crops shape shallow and steep RSA in normal and drought conditions, respectively • ABA biosynthetic mutants exhibit a shallow RSA with no response to drought conditions • ABA acts upstream of auxin biosynthesis signaling in root drought response Xiong et al. uncover a mechanism in rice and maize whereby ABA modulates auxin biosynthesis at the root tip, thereby controlling gravitropic machinery and root angle in response to drought conditions, suggesting the potential applicability of ABA for enhancing drought tolerance in cereal crops. [ABSTRACT FROM AUTHOR]

Auxin, a crucial plant hormone, plays a pivotal role in regulating various aspects of rice growth and development, including cell elongation, root formation, and responses to environmental stimuli. Recent breakthroughs in auxin research have revealed novel regulatory mechanisms, such as the identification of auxin-related genes like DNR1 and OsARF18, which enhance rice nitrogen use efficience and resistance to glufosinate. Additionally, advancements in understanding auxin transport and signaling pathways have highlighted their potential in optimizing tillering, root architecture, and grain yield. This review examines these molecular mechanisms and their interactions with other hormones, emphasizing their integration into breeding programs for improved rice productivity. By synthesizing these findings, we provide a comprehensive overview of how auxin research informs strategies for developing rice varieties with enhanced adaptability and optimized growth, contributing to food security and sustainable agriculture. [ABSTRACT FROM AUTHOR]

Symbiotic nitrogen fixation, recognized as the most efficient nitrogen assimilation system in ecosystems, is essential for soybean growth, as nodulation provides critical nitrogen to host cells. Soybeans thrive in warm and moist environments. However, they are highly susceptible to low temperatures, which impede the formation and development of root nodules. The genetic basis and molecular mechanism underlying the inhibition of nodulation induced by low temperatures remain unclear. In this study, we conducted a comparative transcriptomic analysis of soybean roots inoculated with rhizobium at 1 DPI (Day Post Inoculation) under normal or cold treatments. We identified 39 up-regulated and 35 down-regulated genes associated with nodulation and nitrogen fixation. Notably, cold-responsive genes including three FRI (Frigida) family genes were identified among differentially expressed genes (DEGs). Further expression pattern analysis of GmFRI-1 demonstrated it being significantly responsive to rhizobium inoculation and its highest expression in nodules. Further investigation revealed that overexpression of GmFRI-1 led to an increase in the nodule number, while RNA interference (RNAi)-mediated gene editing of GmFRI-1 suppressed nodule formation. Additionally, GmFRI-1 overexpression may regulate soybean nodulation by modulating the expression of GmNIN (NODULE INCEPTION), GmNSP1 (nodulation signaling pathway 1), and GmHAP2-2 (histone- or haem-associated protein domain) in the nod factor signaling pathway. This study offers new insights into the genetic basis of nodulation regulation under cold stress in legumes and indicates that GmFRI-1 may serve as a key regulator of nodule formation under cold stress. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop an efficient micropropagation protocol for Pueraria tuberosa, a medicinally valuable woody liana species. The nodal explants derived from in vitro-grown seedlings were cultured on Murashige and Skoog (MS) medium containing various combinations of 6-benzylaminopurine (BAP), thidiazuron (TDZ), indole-3-acetic acid (IAA), and indole-3-butyric acid (IBA). These combinations led to the substantial development of multiple shoots. The combination of TDZ (0.57 µM/L) and IBA (0.12 µM/L) resulted in the highest regeneration rate (85%), maximum number of shoots (5.52 ± 0.67), and best shoot length (4.96 ± 0.33 cm). The most effective in vitro rooting treatment consisted of half-strength MS medium accompanied by 2.46 µM/L IBA and a 10-minute pulse treatment with the same concentration of IBA. This treatment resulted in the highest root formation (100%) and maximum roots per shoot (16.72 ± 1.81), with the highest root length (3.58 ± 0.54 cm) among all treatments tested. After four weeks under field conditions, hardened in vitro plantlets showed an 88.2% survival rate. The genetic fidelity of regenerated plants was assessed using inter-simple sequence repeat (ISSR) and random amplified polymorphic DNA (RAPD) markers, which produced monomorphic bands, demonstrating the genetic homogeneity of regeneration and reliability of the in vitro propagation method. [ABSTRACT FROM AUTHOR]

• Embryonic axis selection as an explant for walnut culture establishment is of paramount importance. • Application of cold treatment along with GA3 increases the overall growth rate and morphogenic response in walnut. • MS medium induces fastest in vitro response, while DKW promotes efficient shoot formation. • Successful acclimatization of chandler cultivar from embryonic axis showcases micropropagation potential. Walnuts (Juglans regia L.) hold significant economic and nutritional value, yet their recalcitrant nature poses challenges for in vitro culture establishment. Given the limitations of conventional propagation methods, this study aimed to optimize a protocol for direct plant regeneration using the embryonic axis as an explant source. We systematically optimized explant pre-treatment, nutrient medium composition, and plant growth regulator (PGR) concentrations. The highest morphogenetic response of 76.63 ± 1.93 % was achieved within 4.88 ± 0.44 days for explants pre-treated at 4 °C for 10 days and cultured on Driver and Kuniyuki Walnut (DKW) medium supplemented with 3.0 mg/L GA₃. Comparative analysis of three nutrient media namely Murashige and Skoog (MS), DKW, and Woody Plant Medium (WPM) revealed that MS medium induced the fastest in vitro response (5.21 ± 0.29 days). In contrast, WPM required the longest induction time (10.33 ± 0.19 days). Whole plant formation was most efficient on MS medium (59.96 ± 3.33 %) and least efficient on WPM (3.10 ± 0.22 %). For shoot formation, DKW medium was superior (55.50 ± 4.85 %), while WPM was the least effective (10.55 ± 0.11 %). Root formation was most successful on MS medium (75.50 ± 4.85 %), contrasting with the lowest rate observed on WPM (8.97 ± 1.19 %). Additionally, the influence of various PGR combinations on MS medium was evaluated using the embryonic axis as an explant source. The highest regeneration rate (74.40 ± 2.20 %) was observed with BAP (0.1 mg/L), GA₃ (2.0 mg/L), and IBA (0.1 mg/L), whereas the lowest rate (2.20 ± 1.10 %) was found with BAP (1.0 mg/L) and 2,4-D (0.1 mg/L). These results underscore the significant impact of nutrient and PGR combinations on morphogenic responses. Following successful in vitro shoot and root induction, the regenerated plants were acclimatized to external environmental conditions, demonstrating the potential of the embryonic axis as an exceptional explant source for walnut micropropagation. This optimized protocol enhances in vitro culture establishment and addresses the limitations of traditional propagation methods facilitating the production of acclimatized walnut plants. [ABSTRACT FROM AUTHOR]

• In vitro propagation via the direct organogenesis pathway of three Alocasia species was established, covering initiation, propagation, regeneration, and acclimatization stages. • A combination of rifampicin, alcohol, and bleach proved suitable sterilization materials for micro bulb explants from the field. • The application of TDZ and BAP was optimal for initiation, individual BAP for proliferation and regeneration, and a mixture of sand and water hyacinth organic manure for acclimatization. • GC/MS successfully identified 69 major compounds, revealing significant variations among roots, tubers, and leaves of in vitro plantlets and acclimatized plants. • Compounds like 9,12-Octadecadienoic acid, Tetrahydrofuran-2-one, and n-Hexadecanoic acid were found in varying abundances across species and organs. Alocasia species, endemic ornamental plants in Indonesia, are of significant economic value due to their rarity, slow growth, and challenges in propagation. Our study investigates the in vitro propagation via direct organogenesis of Alocasia cuprea, Alocasia reversa, and Alocasia reginula , alongside bioactive metabolite analysis using GC/MS. The in vitro propagation process for these species encompasses stages including sterilization, shoot initiation, proliferation, regeneration, and acclimatization. Combining pre-sterilization techniques with sterilization methods, including rifampicin treatment (0.1 %), alcohol, and clorox, shows promise in reducing contamination rates. Various media and TDZ-BAP concentrations were tested for shoot initiation, with A. cuprea showing optimal response to the MS medium with 1.0 mg/L TDZ and 0.5 mg/L BAP. Shoot proliferation varied by genotype and medium, with A. cuprea exhibiting the highest proliferation on MS medium with 1.5 mg/L BAP. During the shoot regeneration stage, A. reversa displayed the highest leaf and root formation, particularly on MS medium with 0.5–1 mg/L BAP, which also proved effective for A. cuprea. Acclimatization results indicated that A. cuprea had the highest plantlet survivability, especially in a mixture of sand and water hyacinth organic manure medium. Metabolite analysis identified 69 compounds revealing significant variations among roots, tubers, and leaves of in vitro plantlets and acclimatized plants. Key metabolites, such as 9,12-Octadecadienoic acid, Tetrahydrofuran-2-one, and n-Hexadecanoic acid, were found in varying abundances across species and organs. These findings provide valuable insights for enhancing propagation techniques and exploring the bioactive potential of Alocasia species, thereby laying a foundation for their sustainable cultivation and exploitation. [ABSTRACT FROM AUTHOR]

This study evaluated and compared the amount of apically extruded debris, unprepared wall surface areas, and dentinal crack formation resulting from root canal preparation using ProTaper Next (PTN), ProTaper Ultimate (PTU), and R-Motion (RM) file systems. Forty-five palatal roots of maxillary first molars were shortened to a uniform length of 12 mm. The samples were divided randomly into 3 groups (n = 15/group) to be prepared using either PTN, PTU, and RM file systems. The investigator adopted modified Myers and Montgomery's approach to replicate the temperature of the human body. Debris was collected in vials and weighed before and after instrumentation with a sensitive balance. Every specimen was irrigated using distilled water during preparation, utilizing a side-vented needle. Weight before instrumentation was subtracted from weight after instrumentation to identify the weight of the collected debris. Cone-beam computed tomography (CBCT) scans were taken before and after canal preparation using a Planmeca ProMax CBCT machine. The unprepared canal surface area was calculated by superimposing preoperative and postoperative CBCT images using the Mimics Medical program. After preparation, a low-speed diamond disc horizontally sectioned the roots at 3, 6, and 9 millimeters from the apex. The specimens were examined under a digital microscope to detect crack formation. Statistical analysis was carried out using one-way (ANOVA) and Tukey (HSD) tests, with a significance level of P <.05. There was no statistically significant difference in the quantity of debris extruded apically and dentinal crack numbers among the 3 shaping files (P >.05). Only the apical third of root canals prepared by PTU displayed a significantly lower unprepared surface area compared to PTN and RM. Instrumentation with PTN, PTU, and RM yielded similar amounts of apically extruded debris and dentinal cracks. The PTU files demonstrated higher effectiveness in preparing the apical third by reducing the unprepared surface area in the prepared root canal. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate adventitious root formation in cuttings obtained from physiologically different old stock material. The ornamental cherry Prunus subhirtella ´Autumnalis´ was used for the experiment. We examined three stock plants, namely a physiologically mature stock plant (about 60 years old) and physiologically juvenile plants (21 years old), which were previously propagated by cuttings, semi-mature stock material and in vitro juvenile stock material. We also investigated the role of phytohormones in the induction phase of adventitious root (AR) formation depending on the physiological age of the stock plant and the time after cutting. High performance liquid chromatography coupled with mass spectrometry (HPLC–MS/MS) was used to identify and quantify the phytohormones. The difference in rooting and quality of the developed AR is observed between semi-mature stock and mature stock material. Cuttings from semi-mature plants rooted in 95.00% of cases, while cuttings from mature stock plants only rooted in 68.33%. The high concentration of strigolactones and jasmonic acid (JA) immediately after severance had an inhibitory effect on the development of adventitious roots, especially in cuttings of mature origin. The development of AR is positively influenced by the increase in indole-3-acetic acid (IAA) 4 h after cutting from the stock plant. Our results show that the formation of adventitious root formation depends on the concentration and ratio between different phytohormones. [ABSTRACT FROM AUTHOR]

Brassinosteroids (BRs) are key phytohormones influencing soybean development, yet their role in symbiosis remains unclear. Here, the RNA-Seq was used to identify important gene associated with BRs and symbiotic nitrogen fixation, and the function of candidate gene was verified by transgenic hairy roots. The result shows that the RNA-Seq analysis was conducted in which BR signaling was found to suppress nodule formation and many DEGs enriched in immunity-related pathways. WGCNA analyses led to the identification of GmWRKY33a as being responsive to BR signaling in the context of symbiosis establishment. Transgenic hairy roots analyses indicated that GmWRKY33a served as a negative regulator of the establishment of symbiosis. The qRT-PCR analysis confirmed that BR signaling upregulates GmWRKY33a , leading to nodulation suppression and activation of soybean immune responses. In summary, our research revealed that BR suppresses root nodule formation by modulating the immune signaling pathway in soybean roots. We further identified that GmWRKY33a, a crucial transcription factor in BR signaling, plays a negative role in the symbiotic establishment. [ABSTRACT FROM AUTHOR]

Adventitious root (AR) formation is a bottleneck for vegetative proliferation. In this study, 13 AHP genes (MdAHPs) were identified in the apple genome. Phylogenetic analysis grouped them into 3 clusters (I, II, III), with 4, 4, and 5 genes respectively. The 13 MdAHPs family members were named MdAHP1 to MdAHP13 by chromosome positions. The physicochemical properties, phylogenetic relationship, motifs, and elements of their proteins were also analyzed. The amino acid quantity varied from 60~189 aa, isoelectric point lay between 4.10 and 8.93, and there were 3~7 protein-conserving motifs. Excluding MdAHP6 , other members' promoter sequences behaved 2-4 CTK response elements. Additionally, the expression characteristics of MdAHPs family members at key stages of AR formation and in different tissues were also examined with exogenous 6-BA and Lov treatments. The results showed that MdAHP3 might be a key member in AR formation. GUS staining indicated that the activity of the MdAHP3 promoter was also significantly enhanced by CTK treatment. The protein interactions of MdAHP3/MdAHP1 and MdAHP3/MdAHP6 were verified. Compared with WT, 35S::MdAHP3 transgenic poplars inhibited AR formation. The above experimental results suggested that MdAHP3, as a key family member, interacts with MdAHP1 and MdAHP6 proteins to jointly mediate AR formation in apple rootstocks. [ABSTRACT FROM AUTHOR]

A protocol for micropropagation of potato (Solanum tuberosum L.) cv. Cooch Behar local retaining the fidelity of the in vitro regenerants was established for the first time. Initially, tuber sprouts were inoculated in Murashige and Skoog (MS) basal medium supplemented with 0.5–1.5 mg/l 6-benzyladenine (BA), kinetin (Kin), meta-Topolin (mT), and zeatin (Zea). A maximum number of shoots was induced in 0.5 mg/l Zea followed by 0.5 mg/l mT. For subsequent rooting, the shoots were inoculated in MS medium supplemented with 1.0–3.0 mg/l indole-3-acetic acid and indole-3-butyric acid (IBA), wherein 1.0 mg/l IBA-fortified medium recorded the maximum number of roots. The mono-phasic micropropagation, i.e., simultaneous multiple shoots and roots formation was achieved in MS medium with combinations of Zea (0.25–1.0 mg/l) with 1.0 mg/l IBA, wherein 0.5 mg/l Zea + 1.0 mg/l IBA exhibited the best results. The micropropagated plantlets were then acclimatized in cocopeat with 100% survival before field evaluation. To ensure the true-to-type nature of the micropropagated plants, the cytology, flow cytometry, inter simple sequence repeats (ISSR), and start codon targeted (SCoT) polymorphism primers based fidelity analyses were carried out. Cytology and flow cytometry confirmed that the micropropagated plants had the same ploidy levels. Likewise, the molecular marker-based genetic fidelity study via ISSR and SCoT primers showed monomorphic banding patterns. The present protocol has the potential for large-scale propagation, conservation, and commercialization of indigenous potatoes and can also be used to study the response of other potato cultivars to in vitro regeneration. [ABSTRACT FROM AUTHOR]

Pugionium cornutum (L.) Gaertn (P. cornutum) has strong tolerance to drought, salt and disease, but the tolerance mechanisms for such stresses in P. cornutum are largely unknown. In this study, we identified the PcNAC25 transcription factor gene in P. cornutum. Its open reading frame was revealed to comprise 891 bp, encoding a protein consisting of 297 amino acids, with an isoelectric point of 6.61. Phylogenetic analysis showed that PcNAC25 was most closely related to ANAC019. The expression of PcNAC25 was induced by dehydration, mannitol, heat, cold, salt stresses and abscisic acid (ABA), salicylic acid (SA), and methyl jasmonate (JA) treatments. A subcellular localization analysis confirmed that PcNAC25 was localized in the nucleus. The overexpressing PcNAC25 lines in Arabidopsis had longer roots than wild-type (WT) lines under drought and salt stress. The overexpression of PcNAC25 improved drought and salt tolerance in transgenic Arabidopsis. Under drought and salt stress, PcNAC25 transgenic lines exhibited higher the CAT, POD and SOD activities and scavenging ability of hydroxyl radical than WT, more proline accumulation than WT and less MDA and H2O2 content and superoxide anion production rate than WT. PcNAC25 transgenic lines also exhibited greater reduced water loss rate of detached leaves than WT. Meanwhile, DAB and NBT staining showed that the accumulation of hydrogen peroxide and superoxide anion in PcNAC25 transgenic lines were also less than WT. In addition, overexpressing PcNAC25 enhanced the expression of drought response genes (DREB2A, SOD4, RD29A, NCED3, POD3, P5CS1, PYR1 and SAG13) and salt response genes NHX, SLAH1, SOS1 and NPF6.3. The mentioned above results indicated that PcNAC25 is a positive regulator that activates ROS-scavenging enzymes and enhances root formation in Arabidopsis, which provided a basis for further research on the molecular mechanism of PCNAC25-mediated regulation of drought and salt stress, and also provided gene resources of drought and salt tolerance. [ABSTRACT FROM AUTHOR]

Root nodules provide nitrogen-based nutrition for soybean. A better understanding of the genetic architecture and molecular mechanisms of nodulation is important for soybean breeding. In this study, principal component analysis (PCA) was performed for root nodule-related traits, and the PC scores of each material were calculated. Nodulation ability was evaluated on the basis of principal component scores. A genome-wide association study (GWAS) was performed to identify single nucleotide polymorphisms (SNPs) associated with root nodule-related traits and PC scores across four environments. Five SNPs were repeatedly identified in the two environments. The supernodulation material NJAU_C156 and the difficult-nodulation material NJAU_C130 were used for transcriptomic analysis. There were 224 common differentially expressed genes (DEGs) for the root system and 167 common DEGs for the root nodules. Enrichment analysis revealed that these DEGs were enriched mainly in oxidoreductase activity, glutathione peroxidase activity, arachidonic acid metabolism, and isoflavone metabolism etc. These genes play important role in the formation and development of root nodules and nitrogen fixation processes. By combining the DEGs obtained from the transcriptomic analysis with the GWAS results, fifteen candidate genes were identified, which were annotated mainly as serine-rich protein-related genes, UDP-glucosyl transferase genes, and genes encoding WRKY family transcription factors. Overall, the loci and candidate genes identified in this study will be helpful to further understand symbiotic nodulation. [ABSTRACT FROM AUTHOR]

Respiratory Burst Oxidase Homologues (RBOHs) are involved in plant growth, development, and stress adaptation. How OsRBOHs affect root hair formation and consequently nutrient acquisition and drought resistance in rice is not well understood. We knocked out six OsRBOH genes in rice that were expressed in roots and identified OsRBOHE as the only one affecting root hair formation. OsRBOHE was strongly expressed in the root epidermis, root hairs and tiller buds. OsRBOHE is localised at the plasma membrane. Knockout of OsRBOHE decreased reactive oxygen species generation in the root hairs and tiller buds, downregulated genes involved in cell wall biogenesis, and decreased root hair length and tillering by 90% and 30%, respectively. Knockout of OsRBOHE decreased phosphorus acquisition only in low available P soil under aerobic conditions, but not in high P soil or under flooded conditions when P was likely not limited by diffusion. Knockout of OsRBOHE markedly decreased drought resistance of rice plants through the effect on root hair formation and the associated rhizosheath. Taken together, OsRBOHE is crucial for root hair formation and tillering and consequently on drought resistance in rice. The contribution of root hairs to P acquisition in rice is limited to aerobic soil. Summary statement: The Respiratory Burst Oxidase Homologues OsRBOHE is crucial for root hair formation and tillering and consequently on drought resistance and grain yield in rice. The contribution of root hairs to phosphorus acquisition in rice is limited to low P soil under aerobic condition. [ABSTRACT FROM AUTHOR]

Although class A auxin response factors (ARFs) are known to regulate adventitious root (AR) development through the canonical SCFTIR1- Aux/IAA-ARF signaling pathway, the regulatory role of class B ARFs in AR development remains largely unclear. Therefore, this research focused on the role of class B ARF transcription factors in peach (Prunus persica 'Shengli') adventitious root formation. Here, we report the role of a class B ARF gene PpARF4 in adventitious root formation in peach. Comparative transcriptome and qRT-PCR analyses showed that the transcription of PpARF4 was significantly up-regulated in auxin-treated stem explants. Y2H assay showed that PpARF4 had no interaction with PpIAAs (AUXIN/INDOLE ACETIC ACIDs). PpARF4 could bind the promoters of lateral root development gene PpLBD16 and auxin transport gene PpPIN1 to activate their transcription. Ectopic overexpression of PpARF4 and PpLBD16 in Arabidopsis promoted AR development. Additionally, PpARF4 could act as a negative regulator of flavone synthesis and thus prevent the explants from browning. The results not only provide novel insights into the functions of ARFs in regulating plant growth and development, but will also be useful for fulfilling asexual propagation by stem cuttings in peach. [ABSTRACT FROM AUTHOR]

Efficient adventitious root formation is essential in micropropagation. Auxin prodrugs, inactive precursors that convert into active auxins within the plant, offer potentially improved rooting control and reduced phytotoxicity. This study investigated the efficacy of dichlorprop ester (DCPE), commercialized as Corasil® and Clemensgros® (originally intended to increase grapefruit size), in promoting in vitro root initiation in the model plant Populus × canadensis, compared to its hydrolyzed form DCP and the related compound C77. DCPE displayed a stronger root-inducing effect than DCP, especially at lower concentrations (0.01 and 0.1 µM). Notably, at 1 µM, both DCP and DCPE induced abundant aerial root formation, a phenomenon not previously observed in poplar with traditional auxin treatments. Metabolite analysis revealed distinct patterns. DCPE treatment resulted in rapid hydrolysis to DCP, leading to faster and more systemic distribution of the active auxin throughout the plant, compared to direct DCP application. C77 treatments showed slower uptake and limited translocation combined with slow metabolism to DCP. These results highlight the potential of auxin prodrugs like DCPE as an effective and controllable auxin source for optimizing in vitro rooting protocols in woody plant species. [ABSTRACT FROM AUTHOR]

Micropropagated Russelia equisetiformis Schltdl. & Cham. were examined using two different types of culture media (MS and WPM) at full strength to optimize the suitable proliferation medium. The optimized culture medium (MS medium + 0.5 mgl-1 of BA) was selected for in vitro shooting and root formation. Based on the tested hydrogel polymer at five rates (0, 12.5, 25, 37.5, and 50% instead of agar percentage), the addition of 25% hydrogel polymer (2 gl-1) caused an increase in all shooting characters. Using hydrogel at 25% in the culture medium under various salinity levels (NaCl at 0, 1000, 2000, 3000, and 4000 ppm) showed a positive response of all recorded characters (shooting and rooting) and in the estimated pigments content in shootlets grown on each salinity level. The secondary metabolites (total tannins, flavonoids, and phenols) as well as proline were highly influenced by saline conditions. Meanwhile, using 25% hydrogel polymer in the culture medium individually or in combination with various salinity levels decreased these compounds. The increased antioxidant activity was obtained at 4000 ppm NaCl and 0% hydrogel polymer, while unstressed shootlets on MS culture medium with added 25% hydrogel caused the lowest antioxidant activity using DPPH or phosphomolybdenum. Using hydrogel led to alleviating salinity stress on the micropropagated russelia plant, and this finding is relatively new. [ABSTRACT FROM AUTHOR]

A study was conducted to access the effectiveness of exogenous application of indole-3-butyric acid (IBA) on adventitious root formation in kiwifruit semi-hardwood stem cuttings (SCs) from Actinidia deliciosa rootstock and Actinidia arguta female scion. Treatment comprised IBA concentrations of 0, 10, 100, 1000, 10,000 and 100,000 ppm. Parallel experiments for A. deliciosa and A. arguta's treatment were arranged in a randomised complete block design, with 12 replications. In A. deliciosa, treatments had significant (p ≤ 0.05) effects in rooting percentage, number of roots, root length, size of callus formation and callus percentage, except for dry root mass. In A. arguta, treatments showed significant (p ≤ 0.05) effects in rooting percentage, number of roots, root length and dry root mass. No callus formation was observed in A. arguta. Relative to the control, in A. deliciosa, the highest (42%) rooting percentage and lengthy (0.301 cm) roots, were observed at 10,000 ppm IBA concentration, whereas the most (0.295) number of roots were produced at 100,000 ppm IBA concentration. Calli percentage (94%) was highest at 100 ppm IBA, while the size of callus formation was the biggest (2.8) at IBA concentration of 100,000 ppm, when compared to the control. In A. arguta, the highest (100%) rooting percentage was achieved at the control (0 ppm), 100 ppm and 10,000 ppm IBA concentrations, whereas the greatest (0.9815) number of roots were observed at the IBA concentration of 10 ppm. Lengthy (1.0839 cm) roots were achieved at IBA concentration of 100 ppm, whereas the greatest (0.1061 g) dry root mass was attained at IBA concentration of 10,000 ppm. In conclusion, the use of growth regulator IBA was effective for root formation in SCs of A. deliciosa rootstock. In A. arguta female scion, IBA application improved the quality of rooting (more and longer roots). IBA application showed its potential in stimulating root development at 10,000 ppm IBA. [ABSTRACT FROM AUTHOR]

In Brazil due to the establishment of new orchards, olive seedling production is growing strongly, while the use of biostimulants in agriculture has been gaining attention due to their benefits in root formation and nutrient absorption. This study evaluated the use of biostimulants for promoting the growth of 3-month-old rooted olive seedlings in pots and to assess the nursery quality of the seedlings. Rooted cuttings of Arbequina, Maria da Fé, and Ascolano 315 cultivars were treated with Azospirillum brasilense (Az) and humic substances (HS), alone and in combination. Growth parameters, such as height and stem diameter, were measured every month and after 150 days, seedlings per treatment were also analysed for aerial and root fresh and dry biomasses. Arbequina exhibited the highest growth rate with Az and best absolute growth rate with Az + HS treatment. The total dry matter of the olive seedlings, comprising both the aerial and root part, was influenced by both Azospirillum brasilense and humic substances, enhancing nitrogen availability. The three treatments showed their positive effects on aboveground growth and overall plant vigour. Despite increased biomass, treated olive seedlings showed no significant height advantage over controls, suggesting that the effects may appear in later developmental stages. [ABSTRACT FROM AUTHOR]

Introduction: The presence of wounds in addition to the excision-induced wounds after severance from the stock plants is known to positively influence adventitious root formation of woody plant cuttings. Previous morphological studies highlighted laser wounding as a technique allowing to precisely control the decisive ablation depth. However, the biochemical processes involved in the response of rooting to the additional wounding remained unexplored. Methods: The present study analyzed changes in the plant hormone and carbohydrate profiles in response to laser treatments of rose leafy single-node stem cuttings (Rosa canina 'Pfänder'). Concentrations of four groups of plant hormones and of carbohydrates were monitored in three different stem sections of the cutting base during the first eight days after excision of cuttings. In addition, histology was employed to investigate anatomical changes at the basal wound and the laser wounds at the start and the end of the experiment after 40 days. Results: Laser ablation caused an increase of vascular tissue dimension directly in the laser wound, and increased the quantity and quality of rooting compared to control cuttings. A clear early local rise of jasmonic acid (JA) was detected directly in wounded areas after laser marking, as well as an increase in abscisic acid (ABA) that persisted for the subsequent days. Indole-3-acetic acid (IAA) levels were relatively high on day zero, but decreased thereafter. Interestingly, higher IAA levels were maintained in the stem section below the axillary bud compared with the opposite section. Laser-treated cuttings presented a clear increase in contents of IAA-amino acid conjugates (IAAGlu and IAAsp) and the oxidation product OxIAA. Differences in concentration of these IAA metabolites were related to the position of the laser wound relative to the axillary bud and leaf. Additionally, laser treatments caused gradually increased levels of the cytokinin N6-isopentenyladenine (iP) in laser-treated zones, and of zeatin riboside specifically when the laser wound was placed on the leaf-bud side. Additional laser wounding reduced starch and sucrose levels in all wounded sections at the end of the evaluation period, independently of the wounding location. Discussion: The results of this study indicate that presence of additional injured tissue triggers a complex biochemical adjustment at the base of the cutting responsible of inducing vascular tissue growth and capable of generating a positive response to adventitious root formation. [ABSTRACT FROM AUTHOR]

Background: Silicon has an important role in regulating water management in plants. It is deposited in cell walls and creates a mechanical barrier against external factors. The aim of this study was to determine the role of silicon supplementation in the synthesis and distribution of callose in oilseed rape roots and to characterize the modifications of cell wall structure of these organs after exposure to drought stress. Histological and ultrastructural analyses were performed to determine the changes in the distribution of arabinogalactan proteins, pectins, and extensin in roots of Brassica napus growing under drought and supplemented with silicon. Callose deposition and the accumulation of callose synthase protein were assessed, followed by transcriptional analysis of callose synthase genes. Results: The results showed that silicon supplementation under drought conditions alter the direction of cortex cell differentiation, promoting fiber formation and proliferation of callose-depositing cells in the roots of the tested plants. This was reflected in an increase in the level of callose synthase and a decrease in the transcriptional activity of the gene encoding this enzyme, indicating regulation based on negative feedback under drought stress. The changes in abundance and distribution of investigated arabinogalactan proteins, pectins and extensin in roots of Si supplemented plants growing under drought stress were observed, indicating cell walls remodeling. Conclusion: Silicon supplementation in oilseed rape roots induced significant changes in cell wall composition, including increased callose deposition and altered pectins and arabinogalactan proteins distribution. These modifications, along with the formation of fibres in the root cortex, likely contribute to enhanced cell wall strength providing a physical barrier against water loss and mechanical stress, as a probable defence mechanism induced during drought stress. [ABSTRACT FROM AUTHOR]

The plant hormone auxin orchestrates almost all aspects of plant growth and development. AUXIN RESPONSE FACTORs (ARFs) control the transcription of auxin-responsive genes, forming cytoplasmic condensates to modulate auxin sensitivity and diversify auxin response regulation. However, the dynamic control of ARF distribution across different subcellular compartments remains largely obscure. Here, we show that three MULTIPLE C2 DOMAIN AND TRANSMEMBRANE REGION PROTEINs (MCTPs), MCTP3, MCTP4, and MCTP6, control ARF nucleocytoplasmic partitioning and determine lateral root development. MCTP3/4/6 are highly expressed in lateral roots and specifically interact with ARF7 and ARF19 to dissolve their cytoplasmic condensates. This promotes ARF nuclear localization in lateral root primordia and enhances auxin signaling during lateral root formation. Our findings confer MCTP as a key switch to modulate auxin responses and outline an MCTP-ARF signaling cascade that is crucial for the establishment of the plant root system. [Display omitted] • MCTP3, MCTP4, and MCTP6 are crucial for lateral root development • MCTP3, MCTP4, and MCTP6 interact with ARF7 and ARF19 • MCTPs control ARF7 and ARF19 nucleocytoplasmic partitioning • MCTPs diversify auxin responses by dynamically controlling ARF protein distribution Xuan et al. report that MCTP3, MCTP4, and MCTP6 control ARF7 and ARF19 condensate dynamics and their nucleocytoplasmic partitioning. This promotes ARF localization to the nucleus and enhances auxin signaling, thereby facilitating lateral root formation and underscoring the role of MCTPs in shaping root architecture. [ABSTRACT FROM AUTHOR]

Adventitious root (AR) formation in plants originates from non-root organs such as leaves and hypocotyls. Auxin signaling is essential for AR formation, but the roles of other phytohormones are less clear. In Arabidopsis, at least two distinct mechanisms can produce ARs, either from hypocotyls as part of the general root architecture or from wounded organs during de novo root regeneration (DNRR). In previous reports, gibberellin acid (GA) appeared to play reverse roles in both types of ARs, since GA treatment blocks etiolation-induced AR formation from hypocotyls, whereas GA synthesis and signaling mutants apparently displayed reduced DNRR from detached leaves. In order to clarify this contradiction, we employed the GA biosynthesis inhibitor paclobutrazol (PBZ) and found that PBZ had positive effects on both types of AR formation in Arabidopsis. Consistently, GA treatment had negative effects on both AR formation mechanisms, while loss of GA synthesis and signaling promoted DNRR under our conditions. Our results show that PBZ treatment can rescue declined AR formation in difficult-to-root leaf explants such as erecta receptor mutants. Furthermore, transcriptional profiling revealed that PBZ treatment altered GA, brassinosteroids, and auxin responses, which included the up-regulation of LBD16 that is well known for its pivotal role in AR initiation. [ABSTRACT FROM AUTHOR]

Summary: The mutualistic interaction between ectomycorrhizal fungi and trees is characterized by the coordinated exchange of soil nutrients with soluble sugars. Despite the importance of this process, the precise mechanism by which sugars are transported from host roots to colonizing hyphae remains unclear.This study aimed to identify the specific membrane transporters responsible for the unloading of sugars at the symbiotic interface, with a focus on the role of the root Sugars Will Eventually Be Exported Transporter (SWEET) uniporters.Our study used RNA sequencing and quantitative PCR to identify PtaSWEET gene expression in Populus tremula × alba–Laccaria bicolor ectomycorrhizal root tips. Our results suggest that symbiosis‐induced PtaSWEET1c is primarily responsible for transporting glucose and sucrose, as demonstrated by the yeast assays. Moreover, we used a promoter‐YFP reporter to confirm the localization of the PtaSWEET1c expression in cortical cells of ectomycorrhizal rootlets, supporting its major role in supplying glucose at the symbiotic interface. Furthermore, our observations confirmed the localization of PtaSWEET1c‐GFP in the plasma membrane. The inactivation of PtaSWEET1c reduced ectomycorrhizal root formation and 13C translocation to ectomycorrhizal roots.Our findings highlight the crucial role of PtaSWEET1c in facilitating glucose and sucrose transport at the symbiotic interface of Populus–L. bicolor symbiosis. [ABSTRACT FROM AUTHOR]

The effect of chemically synthesized nanocomposites (NCs) of selenium (Se/AG NC), copper oxide (Cu/AG NC) and manganese hydroxide (Mn/AG NC), based on the natural polymer arabinogalactan (AG), on the processes of growth, development and colonization of potato plants in vitro was studied upon infection with the causative agent of potato blackleg—the Gram-negative bacterium Pectobacterium carotovorum—and the causative agent of ring rot—the Gram-positive bacterium Clavibacter sepedonicus (Cms). It was shown that the infection of potatoes with P. carotovorum reduced the root formation of plants and the concentration of pigments in leaf tissues. The treatment of plants with Cu/AG NC before infection with P. carotovorum stimulated leaf formation and increased the concentration of pigments in them. A similar effect was observed when potatoes were exposed to Mn/AG NC, and an increase in growth and root formation was also observed. The infection of plants with Cms inhibited plant growth. Treatment with each of the NCs mitigated this negative effect of the phytopathogen. At the same time, Se/AG and Mn/AG NCs promoted leaf formation. The Se/AG NC increased the biomass of Cms-infected plants. The treatment of plants with NCs before infection showed a decrease in the intensity of the colonization of plants by bacteria. The Se/AG NC had the maximum effect, which is probably due to its high antioxidant capacity. Thus, the NCs are able to mitigate the negative effects of bacterial phytopathogens on vegetation and the intensity of colonization by these bacteria during the infection of cultivated plants. [ABSTRACT FROM AUTHOR]

ABSTRACT Lack of O2 and high concentrations of iron (Fe) are common in flooded soils where Rice (Oryza sativa L.) is cultivated. We tested the hypothesis that growing in stagnant or high Fe conditions might induce the formation of apoplastic barriers in roots with different properties and chemical compositions. We measured radial O2 loss (ROL) from intact roots, the chemical composition of roots and the formation of root iron plaques in Fe‐sensitive and Fe‐tolerant rice genotypes grown in aerated, deoxygenated stagnant solutions or in aerated solutions containing high concentrations of Fe. Roots of plants grown in stagnant conditions developed tight barriers to ROL, while those grown in high Fe conditions developed only partial barriers. Chemical analysis of enzymatically isolated sclerenchyma/exodermal root cells indicated that roots grown in stagnant conditions showed increased amounts of suberin and glycerol esters. In contrast, roots in high Fe conditions showed an increase in suberization along with formation of iron plaques covering the roots. In high Fe conditions, exodermal suberization and the formation of partial ROL barriers were not influenced by the genotype's tolerance to Fe. The amount of O2 diffused from roots is influenced by the various layers that impede O2 diffusion. Specifically, increased amounts of glycerol esters in the suberized exodermis provide the greater resistance to ROL. [ABSTRACT FROM AUTHOR]

Legumes establish endosymbioses with arbuscular mycorrhizal (AM) fungi or rhizobia bacteria to improve mineral nutrition. Symbionts are hosted in privileged habitats, root cortex (for AM fungi) or nodules (for rhizobia) for efficient nutrient exchange. To reach these habitats, plants form cytoplasmic cell bridges, key to predicting and guiding fungal hyphae or rhizobia-filled infection thread (IT) root entry. However, the underlying mechanisms are poorly studied. Here we show that unique ultrastructural changes and calcium (Ca2+) spiking signatures, closely associated with Medicago truncatula Annexin 1 (MtAnn1) accumulation, accompany rhizobia-related bridge formation. Loss of MtAnn1 function in M. truncatula affects Ca2+ spike amplitude, cytoplasmic configuration and rhizobia infection efficiency, consistent with a role of MtAnn1 in regulating infection priming. MtAnn1, which evolved in species establishing intracellular symbioses, is also AM-symbiosis-induced and required for proper arbuscule formation. Together, we propose that MtAnn1 is part of an ancient Ca2+-regulatory module for transcellular endosymbiotic infection. This study describes ultrastructural changes and cell-specific calcium responses that accompany cytoplasmic bridge formation in legume root cells committed to symbiotic rhizobial infection, with fine-tuning by a calcium-binding annexin. [ABSTRACT FROM AUTHOR]

Microbial pathogens and other parasites can modify the development of their hosts, either as a target or a side effect of their virulence activities. The plant‐pathogenic bacterium Ralstonia solanacearum, causal agent of the devastating bacterial wilt disease, is a soilborne microbe that invades host plants through their roots and later proliferates in xylem vessels. In this work, we studied the early stages of R. solanacearum infection in the model plant Arabidopsis thaliana, using an in vitro infection system. In addition to the previously reported inhibition of primary root length and increase in root hair formation at the root tip, we observed an earlier xylem differentiation during R. solanacearum infection that occurs in a HrpG‐dependent manner, suggesting that the pathogen actively promotes the development of the vascular system upon invasion of the root. Moreover, we found that the phytohormone auxin, of which the accumulation is promoted by the bacterial infection, is required for the R. solanacearum‐triggered induction of root hair formation but not earlier xylem differentiation. Altogether, our results shed light on the capacity of R. solanacearum to induce alterations of root developmental pathways and on the role of auxin in this process. [ABSTRACT FROM AUTHOR]

Cytokinin signalling plays both positive and negative roles in plant resistance to pathogens. It is not clear whether the role of cytokinin changes at the different stages of pathogen infection. Arabidopsis thaliana sequentially exhibits distinct root morphological symptoms during Ralstonia solanacearum infection, which offers a good system to investigate function of cytokinin in the whole pathogen infection process. Using this system, we found increase of cytokinin signalling by Lonely Guy 2 (LOG2) overexpression or depletion of type‐A Arabidopsis Response Regulators (ARRs), negative regulators of cytokinin signalling pathway, promoted cell death, wilting symptom and bacterial growth, but attenuated primary root growth inhibition and lateral root formation. The decrease of cytokinin signalling by mutation on Isopentenyl Transferases (IPTs) inhibited root hair formation, cell death, wilting symptom and bacterial colonisation. Application of different concentration of exogenesis 6‐benzylaminopurine (6‐BA) showed first promoted, then decreased root hair formation. Moreover, application of 6‐BA accelerated cell death but suppressed lateral root formation and primary root growth inhibition. The diverse roles of cytokinin in these different root disease phenotypes suggested function of cytokinin during plant responses to R. solanacearum is cell type‐specific, which provides new insights on roles of cytokinin signalling in regulation on plant–pathogen interactions. [ABSTRACT FROM AUTHOR]

De novo root regeneration is the process by which adventitious roots form around the wound site from wounded or detached plant organs. The de novo root regeneration process has been widely exploited in cutting technology used for vegetative propagation. Here, we employed detached leaf explants from Arabidopsis thaliana to form adventitious roots for studying the process of de novo root regeneration. GUS staining showed that the expression of CLAVATA3/EMBRYO SURROUNDING REGION-RELATED26(CLE26) was gradually increased surrounding the wound site of leaf explants during adventitious root formation. Semi-thin sections further showed that the expression pattern of CLE26 was closely linked to the formation of adventitious roots. Next, genetic analyses confirmed that the CLE26 gene was involved in de novo root regeneration. Furthermore, RNA sequencing (RNA-seq) of the leaf explants revealed that stress-related genes might be involved in CLE26-mediated adventitious root formation. Specifically, genes associated with the hydrogen peroxide catabolic process and oxidative stress response were predominantly upregulated in the cle26 mutant. In contrast, genes involved in the response to salicylic acid were largely downregulated in the cle26 mutant. Overall, our study indicates that the mutation in CLE26 might upregulate the expression of genes involved in reactive oxygen species metabolism or suppress the expression of genes associated with salicylic acid synthesis, thus promoting the formation of adventitious roots. These findings suggest that CLE26 is a potential candidate for the genetic improvement of adventitious rooting in cuttings. [ABSTRACT FROM AUTHOR]

Cell totipotency and pluripotency are the cellular basis for root regeneration in Platycladus orientalis (L.) Franco cuttings, and the regeneration of adventitious roots is a key determinant for improving stem-cutting. However, the cellular basis and physiological regulation of adventitious root formation are still ambiguous. In this research, root primordia initiation and organogenesis were histologically observed, dynamic alterations in soluble proteins were monitored, and tandem mass tag protein profiling during adventitious root development was carried out. It was explicitly shown that the root primordium primarily originated from undifferentiated xylem cells for indirect (callus) rooting and from dividing cells in the cortex for direct (cortex) rooting. During the entire process of adventitious root development, the activities of peroxidase and polyphenol oxidase peaked, and the activity of indole acetic acid oxidase decreased during the prophase of adventitious root formation in both the direct and indirect rooting, suggesting the positive regulation of peroxidase and polyphenol oxidas and the negative regulation of indole acetic acid oxidase during adventitious root initiation. Compared with those of indirect rooting, the relatively greater activities of peroxidase and polyphenol oxidas and lower activity of indole acetic acid oxidase were related to direct rooting and the number of adventitious roots. A total of 4265 proteins were identified from the base of the cuttings, of which 343, 236 and 37 proteins were highly expressed before treatment, in root primordia induction to adventitious root formation, and adventitious root elongation stages, respectively. Through hierarchical cluster analysis, 23 peroxidase and endogenous hormone regulatory proteins were screened and obtained. These included 10 peroxidases, 1 auxin regulatory protein, 3 ABA regulatory proteins, 2 jasmonic acid regulatory proteins and 3 gibberellin regulatory proteins, which were highly expressed during the late cutting period. Finally, a hypothetical model of the regulatory network of the differential proteins involved in adventitious root formation in P. orientalis was constructed. [ABSTRACT FROM AUTHOR]

Summary: Arsenic poses a global threat to living organisms, compromising crop security and yield. Limited understanding of the transcriptional network integrating arsenic‐tolerance mechanisms with plant developmental responses hinders the development of strategies against this toxic metalloid.Here, we conducted a high‐throughput yeast one‐hybrid assay using as baits the promoter region from the arsenic‐inducible genes ARQ1 and ASK18 from Arabidopsis thaliana, coupled with a transcriptomic analysis, to uncover novel transcriptional regulators of the arsenic response.We identified the GLABRA2 (GL2) transcription factor as a novel regulator of arsenic tolerance, revealing a wider regulatory role beyond its established function as a repressor of root hair formation. Furthermore, we found that ANTHOCYANINLESS2 (ANL2), a GL2 subfamily member, acts redundantly with this transcription factor in the regulation of arsenic signaling. Both transcription factors act as repressors of arsenic response. gl2 and anl2 mutants exhibit enhanced tolerance and reduced arsenic accumulation. Transcriptional analysis in the gl2 mutant unveils potential regulators of arsenic tolerance.These findings highlight GL2 and ANL2 as novel integrators of the arsenic response with developmental outcomes, offering insights for developing safer crops with reduced arsenic content and increased tolerance to this hazardous metalloid. [ABSTRACT FROM AUTHOR]

By providing adaptive advantages to plants, desert microorganisms are emerging as promising solutions to mitigate the negative and abrupt effects of climate change in agriculture. Among these, pseudomonads, commonly found in soil and in association with plants' root system, have been shown to enhance plant tolerance to salinity and drought, primarily affecting root system architecture in various hosts. However, a comprehensive understanding of how these bacteria affect plant responses at the cellular, physiological and molecular levels is still lacking. In this study, we investigated the effects of two Pseudomonas spp. strains, E102 and E141, which were previously isolated from date palm roots and have demonstrated efficacy in promoting drought tolerance in their hosts. These strains colonize plant roots, influencing root architecture by inhibiting primary root growth while promoting root hair elongation and lateral root formation. Strains E102 and E141 increased auxin levels in Arabidopsis, whereas this effect was diminished in IAA‐defective mutant strains, which exhibited reduced IAA production. In all cases, the effectiveness of the bacteria relies on the functioning of the plant auxin response and transport machinery. Notably, such physiological and morphological changes provide an adaptive advantage to the plant, specifically under stress conditions such as salinity. Collectively, this study demonstrates that by leveraging the host's auxin signalling machinery, strains E102 and E141 significantly improve plant resilience to abiotic stresses, positioning them as potential biopromoters/bioprotectors for crop production and ecosystem restoration in alignment with Nature‐based Solution approaches. [ABSTRACT FROM AUTHOR]

Hypericum bilgehan bilgilii is a local endemic species distributed in Turkiye. Since the related species is endemic and there are grazing activities in its habitat, in vitro regeneration and in vitro cultures should be established. In addition, considering that the species may have medicinal properties similar to other Hypericum species, an effective in vitro regeneration method(s) should be found. For this reason, a more effective in vitro regeneration method has been established by using benzyl amino purine and 2,4 dichloro phenoxy acetic acid plant growth regulators (PGRs) for the first time in Hypericum bilgehan bilgilii. In this study, different concentrations and combinations of 2,4-D (0.3, 0.4, 0.5, and 1.0) and BAP (0.6, 0.8, 1.0, and 2.0) PGRs have been used for callus formation. It has been established that the best callus formation among the treatment groups occurs in MS supplemented with 0.8 mg L–1 BAP + 0.4 mg L–1 2,4-D. The best shoot growth has been found in MS medium containing 2.0 mg L–1 BAP. The best treatment group in root formation was MS supplemented with 1.0 mg L–1 IBA. It has been observed that the in vitro regenerated seedlings successfully adapted to the acclimatization stage. In the study, in vitro regeneration of Hypericum bilgehan-bilgilii using BAP and 2,4 D PGRs has been performed for the first time, and in vitro, cultures have been established for future plant biotechnology and in vitro conservation studies. [ABSTRACT FROM AUTHOR]

Recalcitrance to root of kiwifruit (Actinidia spp.) stem cuttings (SCs) is a restriction for its commercial production. Exogenous hormone is the key factor to regulate root formation, but the research on exogenous hormone stimulatory effects on Actinidia spp. is still lagging. Kiwifruit plants had been mostly propagated by seeds. However, vegetative propagation offers several advantages over sexual propagation, among them being crop homogeneity, practicability, and simplicity of the technique. A study was therefore conducted to investigate the potential responses of kiwifruit SCs from Actinidia deliciosa rootstock and Actinidia arguta male scion SCs treated with indole-3-butyric acid (IBA) concentrations at low (10, 100 ppm), medium (1,000, 10,000 ppm) and high (100,000 ppm) levels. Parallel experiments for A. deliciosa and A. arguta 's treatments were arranged in a randomized complete block design, with 12 replications. Treatments comprised different IBA concentrations, namely, 0 (control), 10, 100, 1,000, 10,000 and 100,000 ppm. At 103 days, rooting percentage, number of roots, root length, dry root mass, size of callus formation and callus percentage were determined. In A. deliciosa SCs, treatments had high significant (p ≤ 0.05) effects in rooting percentage, number of roots, root length, size of callus formation and callus percentage, except for dry root mass. In A. arguta male SCs, treatments also, showed high significant (p ≤ 0.05) effects in the number of roots, root length and dry root mass, except for the rooting percentage. No callus formation was observed in A. arguta male SCs. Relative to the control, in A. deliciosa SCs, the highest (42%) rooting percentage and lengthy (0.3 cm) roots, both were observed at the medium (10,000 ppm) IBA concentration, whereas the most (0.29) number of roots were produced at the highest (100,000 ppm) IBA concentration. Calli percentage (94%) was highest at low (100 ppm) IBA, while the biggest (2.8) size of callus formation was at the highest IBA concentration of 100,000 ppm, when compared to the control. In A. arguta male SCs, the greatest number of roots (1.08) and root mass (0.07 g) were attained at the medium IBA concentration of 10,000 ppm. The longest (0.94 cm) root length was achieved at the low IBA concentration of 100 ppm. The SCs of A. arguta male scion required low to medium (100 to 10,000 ppm) concentrations of IBA for proper roots stimulation and development, whereas in SCs of A. deliciosa , highest rooting percentage paired with callus formation, was achieved at medium to higher (10,000 to 100,000 ppm) IBA concentrations. Principal component analysis (PCA) revealed that PC1 and PC2 accounted for 99% of the entire variation. While PC1 accounted for 94% of the total variation, PC2 accounted for 5% of the total variation in A. deliciosa. However, in A. arguta PCA revealed that PC1 and PC2 accounted for 93% of the entire variation. While PC1 accounted for 72% of the total variation, PC2 accounted for 21% of the total variation. The use of exogenous application of IBA was effective for adventitious root formation in SCs of A. deliciosa rootstock and A. arguta male scion. IBA showed its effectiveness in stimulating root development at 10000 ppm IBA. [ABSTRACT FROM AUTHOR]

Garcinia brasiliensis, a plant native to the Amazon Rainforest, possesses diverse medicinal properties. In vitro cultivation of this species is pivotal for both production and biochemical studies. Thus, this study aimed to evaluate different combinations of 2iP and 2,4-D in the induction of callogenesis and organogenesis in zygotic embryos of G. brasiliensis. Transverse sections of zygotic embryos were cultured in various combinations of 2iP (0, 1.83, 3.66, 7.32 e 14.63 mg L− 1) and 2,4D (0, 0.45, 2.26, 4.08 e 6.34 mg L− 1) using Wood Plant Medium (WPM). Callogenesis, shoot formation, and root development were assessed. Callus sections at 20 days were stained with toluidine blue and Lugol’s solution for histological evaluations. Shoots were formed in the combination of 3.66 mg L− 1 2iP + 0.45 mg L− 1 2,4-D on the 30th day, multiple roots grew in 2.29 mg L− 1 2,4-D, and radicles were induced at a concentration of 3.66 mg L− 1 2iP. The highest callogenesis occurred with 14.63 mg L− 1 2iP and 6.34 mg L− 1 2,4-D. Histological assessments revealed different cell types and concentric arrangements, constituting centers with meristematic activity, as well as the presence of intercellular space, indicating disorganized tissue. In conclusion, various combinations of 2iP and 2,4-D induce the formation of callus, roots, or radicles in embryos of G. brasiliensis. [ABSTRACT FROM AUTHOR]

Managing teeth with open apices can be a challenging scenario for clinicians. This case report describes the 24‐year follow‐up of a maxillary central incisor that failed to develop after a traumatic injury resulting in a wide‐open apex. A 10‐year‐old girl presented complaining of discomfort in her upper teeth. Tooth #9 had received a traumatic blow several years before and was discoloured with a resin composite restoration on the mesio‐incisal edge. The tooth was painful to percussion and palpation. An inadequate root canal filling and incomplete root formation were observed on the initial periapical radiograph. Root canal retreatment was initiated, and the canal filled entirely with mineral trioxide aggregate (MTA) because of the extremely wide canal and open apex. The patient was asymptomatic at the 24‐year follow‐up with the cone beam computed tomography and periapical radiographs demonstrating the stability of the MTA. [ABSTRACT FROM AUTHOR]

Rhizosphere microorganisms play an important role in the health and development of root systems. Investigating the microbial composition of the rhizosphere is central to understanding the inter-root microbial function of Arundo donax under various cultivation conditions. To complement the metagenomic study of the Arundo donax rhizosphere, here, an amplicon-based metagenomic survey of bacteria and fungi was selected as a practical approach to analyzing the abundance, diversity index, and community structure of rhizosphere bacteria and fungi, as well as to study the effects of different cultivation methods on rhizosphere microbial diversity. Next-generation sequencing and QIIME2 analysis were used. The results indicated that microbial community richness, diversity, and evenness of the hydroponic samples were lower than those of soil samples when examining the α diversity indices of bacteria and fungi using Chao1, ACE, and Shannon metrics. In particular, the relative abundances of Proteobacteria, Rhizobiales, and Incertae sedis in hydroponic materials were higher, while Basidiomycota, Ascomycota, and Actinobacteriota dominated the flora in soil materials when comparing the numbers of OTUs and the ACE community richness estimator. Furthermore, the rhizosphere of hydroponic A. donax contained a higher abundance of nitrogen-fixing bacteria and photosynthetic bacteria, which contribute to root formation. Additionally, there was a significant presence of Basidiomycota, Ascomycota, and Actinobacteriota in soil A. donax, which can form hyphae. This reveals that the microbial community composition of the A. donax rhizosphere is significantly different under various cultivation conditions, suggesting that employing two distinct culturing techniques for Arundo donax may alter the microbiome. Furthermore, it provides technical support for the synergistic interaction between Arundo donax and rhizosphere microorganisms so as to better use the relationship between Arundo donax and basic microorganisms to solve the problems of Arundo donax growth and ecological restoration. [ABSTRACT FROM AUTHOR]

Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), poses a significant threat to global banana production. This study used a GFP-tagged subtropical race 4 strain of Foc (GFP-Foc-STR4) to trace the pathogen's movement in different banana cultivars. These include a race 4 resistant cultivar FHIA25 and the Cavendish somaclone 'GCTCV119', as well as susceptible cultivars including 'Lady Finger', 'FHIA02', and 'Williams' Cavendish. GFP localization revealed that GFP-Foc-STR4 was able to infect all tested cultivars, moving from the roots to the rhizome and aerial parts of the plant. Tyloses formation in root and rhizome vasculature, visualised with GFP autofluorescence and confirmed by scanning electron microscopy, was found to restrict Foc within the xylem vessels, slowing its spread but not fully preventing infection. This containment mechanism contributes to the host tolerance of 'FHIA25' and 'GCTCV119', though it does not confer complete immunity. The use of the fluorescently tagged Foc strain provides valuable insight into the infection process, and supports efforts in the integrated management of Fusarium wilt of banana. [ABSTRACT FROM AUTHOR]

Euryodendron excelsum H. T. Chang, a monotypic plant endemic to China, exhibits significant variations in adventitious root formation in cuttings across different age groups through unclear molecular mechanisms. In this study, we performed RNA-sequencing (RNA-seq) and data analysis at three stages—initial excision (S0), root primordia (S1), and emergence of adventitious roots (S2)—for lateral buds from transplanted triennial tissue culture seedlings and decennial E. excelsum plants. We identified 13,424 differentially expressed genes (DEGs) between different rooting stages and age groups, including 8216 upregulated and 5208 downregulated genes. A Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis indicated that the S1 and S2 DEGs identified were mainly involved in phenylpropanoid biosynthesis, plant hormone signal transduction, plant–pathogen interactions, biosynthesizing various secondary plant metabolites, and starch and sucrose metabolism. Key auxin-pathway genes were expressed at significantly higher levels in culture seedlings than in adult plants, as were WUSCHEL-related homeobox and LATERAL ORGAN BOUNDARIES DOMAIN genes (related to adventitial root growth and development), which together promote the formation, growth, and development of adventitial root primordia. The dysregulated expression of 15 DEGs identified by RNA-seq were verified via real-time quantitative polymerase chain reaction analysis. This study investigates the morphological processes of adventitious root formation in cuttings of E. excelsum of different ages, and the potential molecular mechanisms involved. Our finding provides a basis for research on cutting propagation, conservation applications, and optimization of tissue culture for E. excelsum, and may help improve the rooting rate of E. excelsum cuttings. [ABSTRACT FROM AUTHOR]

The advancement of the kiwifruit industry in South Africa (SA), necessitates the development of other kiwifruit cultivars to supplement the Actinidia deliciosa kiwifruit. However, rooting difficulties are often experienced without the use of plant growth regulators. The effect of Indole-3-butyric acid (IBA) alone and in combination with Naphthalene acetic acid (NAA) on rooting Actinidia chinensis stem cuttings was investigated. The study was conducted at Politsi Nursery, Tzaneen, Limpopo province of SA in 2021-22, mainly during winter months (May-August) for 120 days. In experiment 1, semi-hardwood stem cuttings were treated with 0 (control), 2500, 5000, 7500 and 10000 ppm IBA. In experiment 2, treatments comprised a combination of various IBA and a constant concentration of NAA, namely, 0 + 0 (control), 2500 + 1000, 5000 + 1000, 7500 + 1000 and 10000 + 1000 ppm, respectively. In experiment 1, the highest (90%) rooting percentage, highest dry root mass (0.45 g) and the longest (7.25 cm) root were obtained at 5000 ppm IBA. In experiment 2, the highest (80%) rooting percentage and number of roots (9.06) were observed at 7500 IBA + 1000 NAA ppm. In conclusion, the use of IBA alone proved its suitability for enhancing rooting percentage, dry root mass and longer root formation compared to IBA in combination with NAA. [ABSTRACT FROM AUTHOR]

Background: The extract from Metasequoia glyptostroboides Hu et Cheng, a rare and endangered species native to China, exhibits numerous biological and pharmacological activities. The species is recalcitrant to rooting during micropropagation, a challenge that has yet to be resolved. In this study, transcriptomic and hormonal analyses were conducted to appreciate the molecular mechanism of adventitious root (AR) formation in optimized rooting conditions. Results: The use of 2/5-strength Woody Plant Medium (WPM) significantly promoted AR formation of M. glyptostroboides shoots while the content of endogenous auxin, cytokinins and gibberellins (GAs) varied at different stages of AR formation. Transcriptomic analysis showed the significant up- or down-regulation of differentially expressed genes (DEGs) associated with plant hormone signal transduction and the phenylpropanoid biosynthesis pathway in response to 2/5-strength WPM. DEGs related to the biosynthesis of indole-3-acetic acid, cytokinins and GAs were identified. Transcript factors involved in 13 families were also revealed. A weighted gene co-expression network analysis indicated a strong correlation between hormones and genes involved in plant hormone signal transduction and the phenylpropanoid biosynthetic pathway. Conclusions: These results indicate that the AR-promoting potential of 2/5-strength WPM in M. glyptostroboides was due to complex interactions between hormones and the expression of genes related to plant hormone signal transduction and the phenylpropanoid biosynthetic pathway. [ABSTRACT FROM AUTHOR]

The root system of a plant is essential for plant growth and development because it absorbs nutrients and water from the soil. The root stem cells are maintained and replenished by the quiescent center and are essential for the formation of the specific root structure. In Arabidopsis , the WUSCHEL-RELATED HOMEOBOX 5 (WOX5) plays a key role in regulating root stem cell fate. However, which factor can directly modulate the stability of WOX5 protein remains totally unknown. Here, we report that the peptidase DA1 (LARGE IN CHINESE) interacts with and cleaves WOX5, resulting in the destabilization of WOX5. Genetic analyses support that DA1 acts through WOX5 to regulate root stem cell function. We further demonstrate that cytokinin (CK) signaling induces the accumulation of DA1 protein, thereby decreasing the abundance of WOX5 protein in the root. Consistent with these results, the mutation in DA1 increases the layers of columella stem cells and influences CK-induced differentiation of columella stem cells. Thus, our results reveal a previously unrecognized mechanism by which the cleavage of WOX5 by DA1 connects CK signaling and root stem cell function in Arabidopsis. [Display omitted] • DA1 interacts with and cleaves WOX5, resulting in the destabilization of WOX5 • DA1 acts through WOX5 to regulate root stem cell function • Cytokinin signaling induces the accumulation of DA1 protein • The cleavage of WOX5 by DA1 connects cytokinin signaling and root stem cell function The transcription factor WOX5 plays a key role in regulating root stem cell fate. Cui et al. find that the peptidase DA1 regulates root stem cell function by interacting with and cleaving WOX5. They further demonstrate that the cleavage of WOX5 by DA1 connects cytokinin signaling and root stem cell function in Arabidopsis. [ABSTRACT FROM AUTHOR]

Paeonia ostii, a plant of substantial economic significance, continues to face constraints in achieving large-scale propagation. In vitro propagation offers a promising avenue for the production of disease-free plants and the genetic transformation of peonies to instill novel traits. However, significant challenges persist in tissue culture, particularly with regards to the reproduction coefficient of shoots and the rooting process. This study reports an efficacious protocol for P. ostii micropropagation, focusing on in vitro root development facilitated through the application of phloroglucinol (PG). Furthermore, the study unveils the molecular signature of P. ostii during in vitro root development. The results indicate that the modified Y3 medium (Y3M), supplemented with 1 mg/L 6-benzyladenine (BA) and 0.1 mg/L α-naphthaleneacetic acid (NAA), is optimal for adventitious bud induction, achieving a 96.67% induction rate and an average of 16.03 adventitious shoots per sample. The highest elongation percentage (92.15%) and the longest average shoot length (3.87 cm) were obtained with Y3M containing 0.3 mg/L BA and 0.03 mg/L NAA. Additionally, the optimal medium for inducing root formation in P. ostii was identified as WPM supplemented with 3 mg/L indole-3-butyric acid (IBA) and 100 mg/L phloroglucinol (PG). Lignin content detection, microscope inspection, and molecular signature results demonstrated that PG enhanced lignin biosynthesis, thereby promoting in vitro rooting of P. ostii. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) is naturally produced by plant cells during normal development and serves as a messenger that regulates cell metabolism. Despite its importance, the relationship between hydrogen peroxide and the target of rapamycin (TOR) pathway, as well as its impact on cell division, has been poorly analyzed. In this study, we explore the interaction of H2O2 with TOR, a serine/threonine protein kinase that plays a central role in controlling cell growth, size, and metabolism in Arabidopsis thaliana. By applying two concentrations of H2O2 exogenously (0.5 and 1 mM), we could correlate developmental traits, such as primary root growth, lateral root formation, and fresh weight, with the expression of the cell cycle gene CYCB1;1, as well as TOR expression. When assessing the expression of the ribosome biogenesis-related gene RPS27B, an increase of 94.34% was noted following exposure to 1 mM H2O2 treatment. This increase was suppressed by the TOR inhibitor torin 2. The elimination of H2O2 accumulation with ascorbic acid (AA) resulted in decreased cell division as well as TOR expression. The potential molecular mechanisms associated with the effects of H2O2 on the cell cycle and TOR expression in roots are discussed in the context of the results. [ABSTRACT FROM AUTHOR]