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Copyright of Forest Research is the property of Forest Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Transient and prolonged waterlogging stress (WS) stimulates ethylene (ET) generation in plants, but their reprogramming is critical in determining the plants' fate under WS, which can be combated by the application of symbiotically associated beneficial microbes that induce resistance to WS. The present research was rationalized to explore the potential of the newly isolated 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-producing fungal endophytic consortium of Aspergillus nomiae (MA1) and Aspergillus fumigatus (MA4) on maize growth promotion under WS. MA1 and MA4 were isolated from the seeds of Moringa oleifera L., which ably produced a sufficient amount of IAA, proline, phenols, and flavonoids. MA1 and MA4 proficiently colonized the root zone of maize (Zea mays L.). The symbiotic association of MA1 and MA4 promoted the growth response of maize compared with the non-inoculated plants under WS stress. Moreover, MA1- and MA4-inoculated maize plants enhanced the production of total soluble protein, sugar, lipids, phenolics, and flavonoids, with a reduction in proline content and H2O2 production. MA1- and MA4-inoculated maize plants showed an increase in the DPPH activity and antioxidant enzyme activities of CAT and POD, along with an increased level of hormonal content (GA3 and IAA) and decreased ABA and ACC contents. Optimal stomatal activity in leaf tissue and adventitious root formation at the root/stem junction was increased in MA1- and MA4-inoculated maize plants, with reduced lysigenous aerenchyma formation, ratio of cortex-to-stele, water-filled cells, and cell gaps within roots; increased tight and round cells; and intact cortical cells without damage. MA1 and MA4 induced a reduction in deformed mesophyll cells, and deteriorated epidermal and vascular bundle cells, as well as swollen metaxylem, phloem, pith, and cortical area, in maize plants under WS compared with control. Moreover, the transcript abundance of ethylene-responsive gene ZmEREB180, responsible for the induction of the WS tolerance in maize, showed optimally reduced expression sufficient for induction in WS tolerance, in MA1- and MA4-inoculated maize plants under WS compared with the non-inoculated control. The existing research supported the use of MA1 and MA4 isolates for establishing the bipartite mutualistic symbiosis in maize to assuage the adverse effects of WS by optimizing ethylene production. [ABSTRACT FROM AUTHOR]

Platycladus orientalis, a common horticultural tree species, has an extremely long life span and forms a graceful canopy. Its branches, leaves, and cones have been used in traditional Chinese medicine. However, difficulty in rooting is the main limiting factor for the conservation of germplasm resources. This study shows that the rooting rates and root numbers of cuttings were significantly reduced in ancient P. orientalis donors compared to 5-year-old P. orientalis donors. The contents of differentially accumulated metabolites (DAMs) in phenylpropanoid (caffeic acid and coniferyl alcohol) and flavonoid biosynthesis (cinnamoyl-CoA and isoliquiritigenin) pathways increased significantly in cuttings propagated from ancient P. orientalis donors compared to 5-year-old P. orientalis donors during adventitious root (AR) formation. These DAMs may prevent the ancient P. orientalis cuttings from rooting, and gradual lignification of callus was one of the main reasons for the failed rooting of ancient P. orientalis cuttings. The rooting rates of ancient P. orientalis cuttings were improved by wounding the callus to identify wounding-induced rooting-promoting metabolites. After wounding, the contents of DAMs in zeatin (5'-methylthioadenosine, cis-zeatin-O-glucoside, and adenine) and aminoacyl-tRNA biosynthesis (L-glutamine, L-histidine, L-isoleucine, L-leucine, and L-arginine) pathways increased, which might promote cell division and provided energy for the rooting process. The findings of our study suggest that breaking down the lignification of callus via wounding can eventually improve the rooting rates of ancient P. orientalis cuttings, which provides a new solution for cuttings of other difficult-to-root horticultural and woody plants. [ABSTRACT FROM AUTHOR]

Featured Application: The developed deep-learning-based computer-aided detection system serves as a powerful tool for the assessment of root dilaceration in dental panoramic radiographs. Understanding usual anatomical structures and unusual root formations is crucial for root canal treatment and surgical treatments. Root dilaceration is a tooth formation with sharp bends or curves, which causes dental treatments to fail, especially root canal treatments. The aim of the study was to apply recent deep learning models to develop an artificial intelligence-based computer-aided detection system for root dilaceration in panoramic radiographs. A total of 983 objects in 636 anonymized panoramic radiographs were initially labelled by an oral and maxillofacial radiologist and were then used to detect root dilacerations. A total of 19 state-of-the-art deep learning models with distinct backbones or feature extractors were used with the integration of alternative frameworks. Evaluation was carried out using Common Objects in Context (COCO) detection evaluation metrics, mean average precision (mAP), accuracy, precision, recall, F1 score and area under precision-recall curve (AUC). The duration of training was also noted for each model. Considering the detection performance of all models, mAP, accuracy, precision, recall, and F1 scores of up to 0.92, 0.72, 0.91, 0.87 and 0.83, respectively, were obtained. AUC were also analyzed to better understand where errors originated. It was seen that background confusion limited performance. The proposed system can facilitate root dilaceration assessment and alleviate the burden of clinicians, especially for endodontists and surgeons. [ABSTRACT FROM AUTHOR]

Deep soil drought represents a low level of deep soil water status that is unsuitable for vegetation growth and transpiration. It can be exacerbated through the excessive water uptake by vegetation during climate droughts, while signs of deep soil drought remain unclear worldwide due to a lack of unified methods and comparative data. In this study, we performed a literature search, focusing on deep soil water profiles (>2 m) and quantification of the degree of deep soil drought as indicated by dried soil layers (DSLs). The results revealed the following: (1) DSLs were distributed worldwide, with mean values of 2.2 ± 0.5 m, 3.3 ± 3.9 m, 14.6% ± 8.3%, and 0.66 ± 0.14 for the formation depth, thickness, soil water content, and quantitative index, respectively; (2) at the global scale, DSLs were more common and more severe under forestland, including shrubland, than under grassland and farmland; (3) DSLs were shaped directly by rooting depth and soil particle composition and indirectly by land use, soil thickness, terrain, and climate. The preliminary investigation of DSL distribution confirms the existence of DSLs globally, something that has not been addressed in previous studies. Our study provides an early warning of DSL formation in association with rooting depth and soil particle composition under an increased drought condition, which in turn harms vegetation production and sustainability. [ABSTRACT FROM AUTHOR]

There is generally a trade‐off in the resistance to drought and to waterlogging. However, several species are sequentially subjected to both stressors in many environments. We evaluated the ecophysiological strategies to cope with multiple sequential stress of waterlogging and drought (W + D) of three taxa differing in stress resistance and root morphology: the phreatophic Eucalyptus camaldulensis (Ec) and two shallow‐rooted willow clones: Salix matsudana x Salix alba (SmxSa) and Salix nigra (Sn4). Individuals of the three taxa were grown in pots and assigned to either of four treatments: Control (well‐watered plants), well‐watered followed by drought (C + D); waterlogged for 15 days followed by drought (W15d + D) and waterlogged for 30 days followed by drought (W30d + D). Biomass allocation, growth (diameter, height, length of leaves, and roots), specific leaf area, stomatal conductance, water potential, hydraulic conductivity of roots and branches, leaf C13and root cortical aerenchyma formation were determined at different stages of the experiment. Ec growth was not affected by W + D, developing tolerance strategies at leaf and whole plant levels. Differential effects of W + D were observed in both Salix clones depending on the time of waterlogging. In Sn4 and SmxSa, the root biomass was affected in W15d + D treatment, but a root tolerance response (aerenchyma and adventitious root formation) was observed in W30d + D. In the three taxa, and contrary to expectations, the previous exposure to a waterlogging period did not increase the susceptibility of the plants to a subsequent drought event. On the contrary, we found tolerance, which depended on the time of waterlogging exposure. [ABSTRACT FROM AUTHOR]

This essay focuses on Hüseyin Cevahir, a revolutionary with roots in the Alevite-Kurdish formation and one of the forgotten student leaders of '68 in Turkey. The essay underscores Cevahir's presence within the Turkish Left as not merely a matter of cultural difference. On the contrary, his silent but transformative effects on the Turkish Left stemmed from his subaltern presence, embodied in a double memory. Cevahir incorporated his knowledge of the racialized community of Dersim, in which he was born, into his intellectual awareness, undermining any sovereign subjectivization under the pretext of the universality of the state. Simultaneously, his subaltern experiences helped him to transfigure the racial structures of domination that shaped the political imaginary of middle-class subjectivity among revolutionary Turkish youth under the pretext of class universality. One can thus infer that the main factor behind Cevahir's oblivion in the counterpublic in Turkey is this double criticism embodied in his persona. [ABSTRACT FROM AUTHOR]

The effects of exogenous auxin IBA on cutting rooting of T. amurensis was studied in the greenhouse, the related physical and chemical characteristics in the rooting process were analyzed to provide support and theoretical guidance for the cutting propagation technology of T. amurensis. Different concentrations of IBA were used to treat the semi-lignified cuttings of T. amurensis, the rooting situation was recorded. The samples were collected regularly to detect the effect of IBA on oxidase activity, endogenous hormone content of cuttings. Results showed that the maximum rooting rate, average root length and root fresh weight of T. amurensis were obtained under 100 mg / L IBA with treatment time 8 h, which were 89. 52%, 14. 19 cm and 913. 43 mg, respectively, better than other treatments. In the rooting process of IBA treatment, the activities of SOD and POD showed a low level at 20 d and 40 d, and a peak value at 30 d. The activities of PPO were lower at 20 d, 30 d and 40 d. The activities of IAAO showed a low level at 20 d and 30 d, and a peak value at 40 d. The content of IAA, the IAA/ ABA value showed a low level at 20 d and 40 d, and a peak value at 30 d. The content of GA3 showed a valley value at 20 d, then increased and maintained a high level. The content of ABA maintained at a low level for 0-30 d, and then increased. The content of ZR showed two peaks at 20 d and 40 d, and a valley value at 30 d. From this, it can be concluded that 100 mg / L IBA with treatment time 8 h had the best rooting effect. The low activity of SOD, POD, PPO and IAAO was beneficial to the formation of callus at the early stage of cutting (20 d), and the high activity of SOD and POD was beneficial to the formation of adventitious roots (30 d), and the high activity of IAAO was beneficial to the elongation of adventitious roots (40 d). Higher ZR content was required in callus formation (20 d), and higher IAA, GA3 content were required in adventitious root formation (30 d), and higher GA3, ABA, ZR content were required in adventitious root elongation and development (40 d). The lower IAA/ ABA and IAA/ ZR was beneficial to callus formation and adventitious root elongation, while the higher was beneficial to adventitious root formation. [ABSTRACT FROM AUTHOR]

Aim: The aim of this retrospective analysis was to evaluate the survival, success and possible complications of transplanted premolars in the posterior region subdivided by developmental stage and patient age. Materials and Methods: This study included patients who underwent tooth transplantation between April 2004 and December 2021. A total of 1654 premolars were transplanted into 1243 patients. Tooth mobility, oral hygiene and periodontal parameters were clinically evaluated. Intraoral radiographs were used to evaluate pulpal and periodontal healing, and root formation. The cumulative survival rate was calculated using the Kaplan–Meier method. Results: Data were subdivided into three groups based on the stage of root development and patient age. The mean age at surgery was 14.5 years. The main indication for transplantation was agenesis, followed by trauma and other indications, such as impacted or malformed teeth. A total of 11 premolars were lost during the study period. The overall survival and success rates in the immature premolar group after an observation period of 10 years were 99.7% and 99.4%, respectively. High survival and success rates (95.7% and 95.5%, respectively) were also observed when fully developed premolars were transplanted into the posterior region of adolescents. In adults, the success rate after 10‐year follow‐up is 83.3%. Conclusions: Transplantation of premolars with developing and fully developed roots is a predictable treatment modality. [ABSTRACT FROM AUTHOR]

Copyright of China Journal of Oral & Maxillofacial Surgery is the property of Shanghai Jiao Tong University, College of Stomatology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Main conclusion: In this study, we report that peroxynitrite is necessary for ethylene-mediated aerenchyma formation in rice roots under waterlogging conditions. Plants under waterlogging stress face anoxygenic conditions which reduce their metabolism and induce several adaptations. The formation of aerenchyma is of paramount importance for the survival of plants under waterlogging conditions. Though some studies have shown the involvement of ethylene in aerenchyma formation under waterlogging conditions, the implication of peroxynitrite (ONOO−) in such a developmental process remains elusive. Here, we report an increase in aerenchyma formation in rice roots exposed to waterlogging conditions under which the number of aerenchyma cells and their size was further enhanced in response to exogenous ethephon (a donor of ethylene) or SNP (a donor of nitric oxide) treatment. Application of epicatechin (a peroxynitrite scavenger) to waterlogged plants inhibited the aerenchyma formation, signifying that ONOO− might have a role in aerenchyma formation. Interestingly, epicatechin and ethephon co-treated waterlogged plants were unable to form aerenchyma, indicating the necessity of ONOO− in ethylene-mediated aerenchyma formation under waterlogging conditions. Taken together, our results highlight the role of ONOO− in ethylene-mediated aerenchyma formation in rice and could be used in the future to develop waterlogging stress-tolerant varieties of rice. [ABSTRACT FROM AUTHOR]

Salvia officinalis, commonly known as sage, is highly valued for its medicinal and ornamental properties. In the present work, 12 native sage populations of north-west Greece were evaluated for eight ornamental traits. Populations from the locations of Aristi, Kefalovryso and Igoumenitsa were selected as the best performing and for their preservation and availability in the market, their asexual propagation was investigated by (a) shoot cutting and (b) in vitro techniques. Propagation by cuttings was investigated during the four seasons. Aristi exhibited the highest rooting (65%) in spring with a well-developed root system (4.7 root number and 5.0 cm length) by applying 0.5 g·L−1 Indole-3-butyric acid, potassium salt (K-IBA), established on perlite under a fog system. However, the rooting performance of Aristi spring cuttings was not affected by different substrates of peat:perlite (0:1, 1:1, 1:2 v/v) or rooting systems (mist, fog) tested. Furthermore, the in vitro propagation of the selected sage populations was investigated using shoot tips as explants. After successful disinfection, the effect of Murashige and Skoog (MS) medium in ten different combinations of Indole-3-acetic acid (IAA), 6-Benzylaminopurine (BAP) and Thidiazuron (TDZ) were tested on shoot multiplication. Aristi presented the highest number of newly formed shoots on MS9 (0.1 mg·L−1 IAA and 0.8 mg·L−1 TDZ) and MS5 (0.1 mg·L−1 IAA and 0.8 mg·L−1 BAP) (3.35 and 3.21 new shoots/explant, respectively) with the highest shoot length (2.23 cm and 3.2 cm) and unexpected spontaneous root formation (64%) at MS5. The rooting ability of Aristi microshoots was further investigated in order to enhance their response. Of the three rooting variants tested, optimal rooting formation (100%) was observed on 0.9 mg·L−1 IAA (R3) combined with successful acclimatization (100%). Aristi exceeded the other populations in both the tested propagation systems, thus holding a strong potential for its introduction in the market as a competitive ornamental variety. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Botanical Research is the property of Bulletin of Botanical Research Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Adventitious roots (ARs) occur naturally in many species and are important for plants to absorb nutrients and water. AR formation can also be induced from explants of trees, whose clonal propagation is needed. AR formation is gridlock for many woody plant mass propagations. Plant hormones have been regarded as playing a key role in AR formation, and the molecular regulatory mechanisms need to be elucidated. In this study, RNA-Seq was performed to reveal the molecular mechanisms in the different periods of AR formation from hybrid poplar clone 84K (Populus alba × P. glandulosa) and AUXIN SIGNALING F-BOX (PagFBL1-OE). To understand the importance of differentially expressed genes (DEGs), we found that many genes involved in signal transduction mechanisms were induced at 12, 24 and 48 h in 84K and PagFBL1-OE cells by NOG classification. We also found that many DEGs were enriched in hormone signal transduction only for the first 12 h in 84K and PagFBL1-OE by KEGG pathway enrichment. Notably, more DEGs appeared in indole-3-acetic acid (IAA), abscisic acid (ABA), ethylene (ETH), jasmonic acid (JA), brassinolide (BR), cytokinin (CTK) and gibberellin (GA) signal transduction for the first 12 h in PagFBL1-OE than in 84K. Moreover, ARF (Pop_G01G075686), IAA14 (Pop_A10G047257), SAURs (Pop_A03G019756, Pop_A12G067965, Pop_G03G055849 and Pop_G12G008821), JAR1s (Pop_A14G000375 and Pop_G14G044264), CTR1 (Pop_A17G052594 and Pop_G09G030293), CRE1s (Pop_G07G086605 and Pop_G07G086618), GID1 (Pop_A04G026477), BKI1 (Pop_A02G066155), PYR/PYLs (Pop_A03G050217 and Pop_G01G089222), and TGAs (Pop_A04G059310, Pop_G04G060065 and Pop_G05G008153) were only specifically expressed in PagFBL1-OE and could play an important role in AR formation, especially in the first 12 h under plant hormone signal transduction. These results show that the complex biological process of AR formation is primarily influenced by the hormone signalling pathway in Populus. This study reveals the initial regulation of AR formation in woody plant cuttings and thus contributes to further elucidating the molecular mechanism by which hormones interact. [ABSTRACT FROM AUTHOR]

Schisandra chinensis (Turcz.) Baill. is an important medicinal plant in northeast China. Cutting propagation is an effective method for the rapid propagation of many tree species. This research aimed to determine a suitable growing medium and appropriate root hormone type, concentration and treatment time through the utilization of different substrates and hormones to treat one-year-old branches of S. chinensis. The optimal treatment achieved a rooting rate of 60% with 225 ppm ABT and 75 ppm NAA for 2.5 h. The substrate of vermiculite/perlite = 1:1 (urea+potassium) was beneficial to the adventitious root formation, which reached 79%. The adventitious root primordium of S. chinensis originated from the junction of the xylem and cambium. ABT and NAA treatments altered the peak timing of POD, PPO and IAAO in S. chinensis cuttings. During the adventitious root formation of S. chinensis cuttings, the high endogenous IAA concentration promoted the occurrence of adventitious roots in the early stage and the lower endogenous IAA and GA3 concentrations promoted the elongation and growth of adventitious roots in the later period. Low ABA and ZR concentrations enabled adventitious root formation and elongation. An efficient cutting propagation system would enable the mass propagation of S. chinensis seedlings. [ABSTRACT FROM AUTHOR]

Rhododendron aureum is identified as a vulnerable species in China. The establishment of an in vitro regeneration system assists significantly in species protection. Here, an in vitro regeneration system was developed using both direct and indirect organogenesis pathways. The role of thidiazuron (TDZ) in different developmental stages was also investigated. The leaves of wild-harvested R. aureum plants were used for callus induction after hydroponic cultivation. The optimal formula was found to be woody plant basal medium (WPM) supplemented with 0.5 mg·L−1 TDZ and 0.5 mg·L−1 3-indolebutyric acid (IBA), while the optimal formula for the subculture and induction of adventitious buds was WPM containing 0.1 mg·L−1 TDZ and 0.5 mg·L−1 IBA. The leaves from tissue-cultured seedlings were then used for the induction of bud clusters. An association was observed between the differentiation of bud clusters and the ratio of auxin and cytokinin. The optimal formula for the induction of bud clusters was WPM containing 0.5 mg·L−1 TDZ and 0.1 mg·L−1 IBA, yielding a 50% induction rate and the maximum number of buds. Higher concentrations of TDZ were found to be beneficial for bud proliferation, while a lower concentration was conducive to stem elongation. The optimal formula for subculture was WPM containing 0.1 mg·L−1 TDZ and 0.5 mg·L−1 IBA, while that for stem elongation was WPM supplemented with 0.002 mg·L−1 TDZ and 0.5 mg·L−1 IBA. Only IBA was found to be necessary for rooting, with increased IBA concentrations leading to an increased number of roots and earlier root formation, with larger callus areas; thus, an IBA concentration of 1.0 mg·L−1 was found to be optimal for the rooting of R. aureum. After hardening the seedlings for two days, a substrate composed of vermiculite and peat soil in a 10:1 ratio was identified as a transplantation formula. This system provides directions both for the protection of endangered species and the promotion of industrial development. [ABSTRACT FROM AUTHOR]

Adventitious root (AR) formation is a critical process in cutting propagation of horticultural plants. Brassinosteroids (BRs) have been shown to regulate AR formation in several plant species; however, little is known about their exact effects on pepper AR formation, and the downstream signaling of BRs also remains elusive. In this study, we showed that treatment of 24-Epibrassinolide (EBL, an active BR) at the concentrations of 20–100 nM promoted AR formation in pepper (Capsicum annuum). Furthermore, we investigated the roles of apoplastic reactive oxygen species (ROS), including hydrogen peroxide (H2O2) and superoxide radical (O2•−), in EBL-promoted AR formation, by using physiological, histochemical, bioinformatic, and biochemical approaches. EBL promoted AR formation by modulating cell-wall-located polyamine oxidase (PAO)-dependent H2O2 production and respiratory burst oxidase homologue (RBOH)-dependent O2•− production, respectively. Screening of CaPAO and CaRBOH gene families combined with gene expression analysis suggested that EBL-promoted AR formation correlated with the upregulation of CaPAO1, CaRBOH2, CaRBOH5, and CaRBOH6 in the AR zone. Transient expression analysis confirmed that CaPAO1 was able to produce H2O2, and CaRBOH2, CaRBOH5, and CaRBOH6 were capable of producing O2•−. The silencing of CaPAO1, CaRBOH2, CaRBOH5, and CaRBOH6 in pepper decreased the ROS accumulation and abolished the EBL-induced AR formation. Overall, these results uncover one of the regulatory pathways for BR-regulated AR formation, and extend our knowledge of the functions of BRs and of the BRs-ROS crosstalk in plant development. [ABSTRACT FROM AUTHOR]

Abstract Background HD-Zips (Homeodomain-Leucine Zippers) are a class of plant-specific transcription factors that play multiple roles in plant growth and development. Although some functions of HD-Zip transcription factor have been reported in several plants, it has not been comprehensively studied in peach, especially during adventitious root formation of peach cuttings. Results In this study, 23 HD-Zip genes distributed on 6 chromosomes were identified from the peach (Prunus persica) genome, and named PpHDZ01-23 according to their positions on the chromosomes. These 23 PpHDZ transcription factors all contained a homeomorphism box domain and a leucine zipper domain, were divided into 4 subfamilies(I-IV) according to the evolutionary analysis, and their promoters contained many different cis-acting elements. Spatio-temporal expression pattern showed that these genes were expressed in many tissues with different levels, and they had distinct expression pattern during adventitious root formation and development. Conclusion Our results showed the roles of PpHDZs on root formation, which is helpful to better understand the classification and function of peach HD-Zip genes.

Abstract Background Auxin plays a crucial role in nitrate (NO3 –)-mediated root architecture, and it is still unclear that if NO3 – supply modulates auxin reallocation for regulating root formation in maize (Zea mays L.). This study was conducted to investigate the role of auxin efflux carrier ZmPIN1a in the root formation in response to NO3 – supply. Results Low NO3 – (LN) promoted primary root (PR) elongation, while repressed the development of lateral root primordia (LRP) and total root length. LN modulated auxin levels and polar transport and regulated the expression of auxin-responsive and -signaling genes in roots. Moreover, LN up-regulated the expression level of ZmPIN1a, and overexpression of ZmPIN1a enhanced IAA efflux and accumulation in PR tip, while repressed IAA accumulation in LRP initiation zone, which consequently induced LN-mediated PR elongation and LR inhibition. The inhibition rate of PR length, LRP density and number of ZmPIN1a-OE plants was higher than that of wild-type plants after auxin transport inhibitor NPA treatment under NN and LN conditions, and the degree of inhibition of root growth in ZmPIN1a-OE plants was more obvious under LN condition. Conclusion These findings suggest that ZmPIN1a was involved in modulating auxin levels and transport to alter NO3 –-mediated root formation in maize.

Root hairs are single-celled tubular structures produced from the epidermis, which play an essential role in water and nutrient uptake from the soil. Therefore, root hair formation and elongation are controlled not only by developmental programs but also by environmental factors, enabling plants to survive under fluctuating conditions. Phytohormones are key signals that link environmental cues to developmental programs; indeed, root hair elongation is known to be controlled by auxin and ethylene. Another phytohormone, cytokinin, also affects root hair growth, while whether cytokinin is actively involved in root hair growth and, if so, how it regulates the signaling pathway governing root hair development have remained unknown. In this study, we show that the two-component system of cytokinin, which involves the B-type response regulators ARABIDOPSIS RESPONSE REGULATOR 1 (ARR1) and ARR12, promotes the elongation process of root hairs. They directly up-regulate ROOT HAIR DEFECTIVE 6-LIKE 4 (RSL4) encoding a basic helix–loop–helix (bHLH) transcription factor that plays a central role in root hair growth, whereas the ARR1/12–RSL4 pathway does not crosstalk with auxin or ethylene signaling. These results indicate that cytokinin signaling constitutes another input onto the regulatory module governed by RSL4, making it possible to fine-tune root hair growth in changing environments. [ABSTRACT FROM AUTHOR]

Ultradian rhythms have been proved to be critical for diverse biological processes. However, comprehensive understanding of the short-period rhythms remains limited. Here, we discover that leaf excision triggers a gene expression rhythm with ~3-h periodicity, named as the excision ultradian rhythm (UR), which is regulated by the plant hormone auxin. Promoter-luciferase analyses showed that the spatiotemporal patterns of the excision UR were positively associated with de novo root regeneration (DNRR), a postembryonic developmental process. Transcriptomic analysis indicated more than 4,000 genes including DNRR-associated genes were reprogramed toward ultradian oscillation. Genetic studies showed that EXCISION ULTRADIAN RHYTHM 1 (EUR1) encoding ENHANCER OF ABSCISIC ACID CORECEPTOR1 (EAR1), an abscisic acid signaling regulator, was required to generate the excision ultradian rhythm and enhance root regeneration. The eur1 mutant exhibited the absence of auxin-induced excision UR generation and partial failure during rescuing root regeneration. Our results demonstrate a link between the excision UR and adventitious root formation via EAR1/EUR1, implying an additional regulatory layer in plant regeneration. [ABSTRACT FROM AUTHOR]

Strigolactones (SLs) are a class of plant hormones and rhizosphere communication signals of great interest. They perform diverse biological functions including the stimulation of parasitic seed germination and phytohormonal activity. However, their practical use is limited by their low abundance and complex structure, which requires simpler SL analogues and mimics with maintained biological function. Here, new, hybrid-type SL mimics were designed, derived from Cinnamic amide, a new potential plant growth regulator with good germination and rooting-promoting activities. Bioassay results indicated that compound 6 not only displayed good germination activity against the parasitic weed O. aegyptiaca with an EC50 value of 2.36 × 10−8 M, but also exhibited significant inhibitory activity against Arabidopsis root growth and lateral root formation, as well as promoting root hair elongation, similar to the action of GR24. Further morphological experiments on Arabidopsis max2-1 mutants revealed that 6 possessed SL-like physiological functions. Furthermore, molecular docking studies indicated that the binding mode of 6 was similar to that of GR24 in the active site of OsD14. This work provides valuable clues for the discovery of novel SL mimics. [ABSTRACT FROM AUTHOR]

Information regarding the physiological and molecular plant responses to the treatment with new biofertilizers is limited. In this study, a fast-composting soil amendment obtained from solid waste by means of a Fenton reaction was assessed to evaluate the effects on the growth of Lactuca sativa L. var. longifolia seedlings. Growth rate, root biomass, chlorophyll concentration, and total soluble proteins of seedlings treated with the 2% fast-composting soil amendment showed significant increases in comparison with the control seedlings. Proteomic analysis revealed that the soil amendment induced the up-regulation of proteins belonging to photosynthesis machinery, carbohydrate metabolism, and promoted energy metabolism. Root proteomics indicated that the fast-composting soil amendment strongly induced the organs morphogenesis and development; root cap development, lateral root formation, and post-embryonic root morphogenesis were the main biological processes enriched by the treatment. Overall, our data suggest that the addition of the fast-composting soil amendment formulation to the base soils might ameliorate plant growth by inducing carbohydrate primary metabolism and the differentiation of a robust root system. [ABSTRACT FROM AUTHOR]

To optimize protocol for obtaining hairy roots of Nitraria schoberi L. with high antiviral activities, factors such as four strain types of Agrobacterium rhizogenes (A4, ATCC15834, R-1601, 8196), two explant types, namely cotyledonous and primary leaves of seedlings, and different cultivation durations (30 and 90 d) were studied. The formation of hairy roots was observed after 2 to 4 wk of incubation, depending on the type of explant and the strain of A. rhizogenes used. The maximum transformation frequency (85.7%) was observed in the cotyledons genetically modified with the strain ATCC15834. The transgenic nature of hairy roots was revealed by PCR with primers to the Agrobacterium oncogenes rolB and rolC. The absence of contamination of the culture by A. rhizogenes was confirmed by primers to the virC and virD1 genes. Phytochemical analysis showed that accumulation of individual metabolites in the line samples exceeded their levels in the native Nitraria roots. Catechin content in the cultures of long-term cultivation (90 d) was found 1.4 to 2.2 times higher than the same samples of short cultivation (30 d) and 4.8 to 10.8 times higher in comparison with the native roots. The most productive in terms of catechin level were hairy roots of long-term cultivation obtained during the transformation of primary leaves of N. schoberi seedlings with ATCC15834 strain. These data were consistent with the highest antiviral activities against influenza viruses of A (H5N1) and A (H3N2) subtypes with neutralization indexes 6.5 to 6.75 log10, and selectivity index values were in the range 15.4 to 16.4. [ABSTRACT FROM AUTHOR]

Pandanustectorius Sol. is an economically important coastal and insular tree with various uses. One objective of this study was to multiply shoots from tiller explants. In addition, the effects of basal media, plant growth regulators (PGRs), and the concentration of coconut water (CW) in P. tectorius tissue culture, specifically shoot proliferation and root formation, were assessed. Woody Plant Medium (WPM) was a more suitable basal medium than Murashige and Skoog (MS) medium for shoot proliferation. The optimal shoot proliferation medium was WPM with 0.5 mg L−1 6-benzyladenine (BA), 0.1 mg L−1 α-naphthaleneacetic acid (NAA), and 5.0% CW, resulting in a shoot proliferation efficiency of 7.9 within 35 d. The optimal rooting medium was WPM with 0.5 mg L−1 indole-3-butyric acid (IBA), leading to 100% rooting without the formation of callus from the shoot base. Survival percentage of transplanted plantlets was 100% after 90 d of observation. Adventitious shoot induction from leaf sheath bases was first investigated. On an MS basal medium with 1.0 mg L−1 2,4-dichlorophenoxyacetic acid (2,4-D), callus was induced within 30 d, and as callus was transferred to MS with 0.5 mg L−1 BA, 0.1 mg L−1 NAA, and 5% CW, mean 2.3 adventitious shoot buds per callus explant were induced. As MS medium contained 1.0 mg L−1 thidiazuron (TDZ), 15.7 adventitious shoots were induced directly. This protocol is useful for the mass propagation of P. tectorius. [ABSTRACT FROM AUTHOR]

C. sinensis is an economically important crop for tea production that experiences increasing demand and good export potential. Therefore, crops need to be expanded, and high-quality planting material is required. Vegetative propagation by cuttings is the prevalent method; therefore, this paper explored its optimization potential modeled on cultivar 'Jiukengzao'. This study wanted to deeply explore blue-light-induced adventitious root formation and development of tea cuttings, so we conducted short-term (0 h, 8 h, and 16 h) and long-term (30 d, 60 d, and 90 d) time-course analyses on tea cutting seedlings. Short-term, full-length transcriptome analysis showed that the expression of genes related to plant hormone signal transduction and auxin transport was highest at 16 h. Sixteen hours of light was considered as suitable for adventitious root growth and development of tea cuttings. Long-term phytohormone analysis showed that the trend of indole-3-carboxylic acid (ICA) change was: 60 d > 90 d > 30 d. Long-term, full-length transcriptome analysis showed that the gene expression trends in K2, K5, K6, and K8 clusters were: 90 d > 60 d > 30 d, and the opposite was observed in K1, K4, and K11 clusters. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that most of the genes in these seven clusters are involved in "plant hormone signal transduction (ko04075)". This includes auxin early responsive protein AUX/IAA, auxin response factor ARF, auxin-responsive protein SAUR, etc. In addition, genes related to auxin transport and synthesis were identified as PIN1, 3, 4, PILS2, 6, 7, flavin-containing monooxygenase YUC9, and YUC10, and the expression trend of these genes was mostly consistent with the change trend of ICA content. This study further explained the molecular mechanism of blue-light-induced adventitious root formation and development of tea cuttings. It is recommended that blue light can be used to promote the adventitious root growth and development of tea cuttings in practical production. [ABSTRACT FROM AUTHOR]

Long noncoding RNAs (lncRNAs) are a large and diverse class of genes in eukaryotic genomes that contribute to a variety of regulatory processes. Functionally characterized lncRNAs play critical roles in plants, ranging from regulating flowering to controlling lateral root formation. However, findings from the past decade have revealed that thousands of lncRNAs are present in plant transcriptomes, and characterization has lagged far behind identification. In this setting, distinguishing function from noise is challenging. However, the plant community has been at the forefront of discovery in lncRNA biology, providing many functional and mechanistic insights that have increased our understanding of this gene class. In this review, we examine the key discoveries and insights made in plant lncRNA biology over the past two and a half decades. We describe how discoveries made in the pregenomics era have informed efforts to identify and functionally characterize lncRNAs in the subsequent decades. We provide an overview of the functional archetypes into which characterized plant lncRNAs fit and speculate on new avenues of research that may uncover yet more archetypes. Finally, this review discusses the challenges facing the field and some exciting new molecular and computational approaches that may help inform lncRNA comparative and functional analyses. [ABSTRACT FROM AUTHOR]

Renanthera imschootiana Rolfe is an extremely rare and endangered tropical epiphytic orchid. Studies on in vitro culture of R. imschootiana were conducted in order to conserve and increase the genetic pool of this wild orchid species. In this study, the effect of plant growth regulators (BA and NAA), ripe bananas in combination with potato, humic acid, and silver nanoparticles (AgNPs) were investigated to find a suitable condition for in vitro plant regeneration from R. imschootiana protocorm-like body (PLB). The results showed that after 45 days of culture, MS medium supplemented with 100 g ripe banana/liter and 100 g potato/liter was suitable for regenerating shoots from the protocorm-like body (PLB) (17.56 shoots/PLBs and 100.00% of shoot-regenerating PLBs); MS medium supplemented with 2.0 mg/L BA, 0.3 mg/L NAA and 4 ppm AgNPs was the most suitable for the growth of shoots after 60 days of culture (10.00 leaves/shoot and shoot length of 4.22 cm). The in vitro shoots were transferred to half-strength MS supplemented with humic acid and AgNPs to investigate the root formation of R. imschootiana. After 60 days of culture, the best rooting was obtained at 2.0 mg/L humic acid and 6 ppm AgNPs (8.33 roots/shoot; root length of 4.00 cm and 100.00% root formation). The findings suggest that the in vitro micropropagation from R. imschootiana protocorm-like body provides a useful alternative tool for the conservation of this endangered species. [ABSTRACT FROM AUTHOR]

INDETERMINATE DOMAIN (IDD) proteins are plant-specific transcription factors that interact with GRAS proteins, such as DELLA and SHORT ROOT (SHR), to regulate target genes. The combination of IDD and DELLA proteins regulates genes involved in gibberellic acid (GA) synthesis and GA signaling, whereas the combination of IDD with the complex of SHR and SCARECROW, another GRAS protein, regulates genes involved in root tissue formation. Previous bioinformatic research identified seven IDDs, two DELLA, and two SHR genes in Physcomitrium patens, a model organism for non-vascular plants (bryophytes), which lack a GA signaling pathway and roots. In this study, DNA-binding properties and protein–protein interaction of IDDs from P. patens (PpIDD) were analyzed. Our results showed that the DNA-binding properties of PpIDDs were largely conserved between moss and seed plants. Four PpIDDs showed interaction with Arabidopsis DELLA (AtDELLA) proteins but not with PpDELLAs, and one PpIDD showed interaction with PpSHR but not with AtSHR. Moreover, AtIDD10 (JACKDAW) interacted with PpSHR but not with PpDELLAs. Our results indicate that DELLA proteins have modified their structure to interact with IDD proteins during evolution from moss lineage to seed plants, whereas the interaction of IDD and SHR was already present in moss lineage. [ABSTRACT FROM AUTHOR]

Pinus tabulaeformis represents a critical virescence, and afforestation species are extensively adopted for ecological governance in northeast China, especially in arid areas of western Liaoning Province. The flora in this region is usually affected by drought stress. We studied the responses of P. tabulaeformis seedlings to diverse water situations after infection with an ectomycorrhizal fungus, Suillus luteus. A controlled pot experiment was carried out using P. tabulaeformis seedlings with or without S. luteus inoculation at non-drought, mild, moderate, and severe drought stresses. S. luteus inoculation markedly enhanced P. tabulaeformis development and survival by promoting growth and photosynthesis as well as elevating stomatal area and density under varying degrees of drought stress. Drought stress groups with S. luteus, in particular, had 19%, 21%, and 5.5% increased dry weights compared to normal water. It also promoted the formation of a strong root system. Treatments with S. luteus seedlings exposed to moderate and severe stress resulted in the highest increase in the main root length, i.e., 112.5 and 127% higher than in normal water. S. luteus may, therefore, serve as the biological modifiers of P. tabulaeformis in terms of ecological management in arid areas of western Liaoning Province, China. [ABSTRACT FROM AUTHOR]

Rhizobia can establish mutually beneficial interactions with legume plants by colonizing their roots to induce the formation of a specialized structure known as a nodule, inside of which the bacteria are able to fix atmospheric nitrogen. It is well established that the compatibility of such interactions is mainly determined by the bacterial recognition of flavonoids secreted by the plants, which in response to these flavonoids trigger the synthesis of the bacterial Nod factors that drive the nodulation process. Additionally, other bacterial signals are involved in the recognition and the efficiency of this interaction, such as extracellular polysaccharides or some secreted proteins. Some rhizobial strains inject proteins through the type III secretion system to the cytosol of legume root cells during the nodulation process. Such proteins, called type III-secreted effectors (T3E), exert their function in the host cell and are involved, among other tasks, in the attenuation of host defense responses to facilitate the infection, contributing to the specificity of the process. One of the main challenges of studying rhizobial T3E is the inherent difficulty in localizing them in vivo in the different subcellular compartments within their host cells, since in addition to their low concentration under physiological conditions, it is not always known when or where they are being produced and secreted. In this paper, we use a well-known rhizobial T3E, named NopL, to illustrate by a multitask approach where it localizes in heterologous hosts models, such as tobacco plant leaf cells, and also for the first time in transfected and/or Salmonella-infected animal cells. The consistency of our results serves as an example to study the location inside eukaryotic cells of effectors in distinct hosts with different handling techniques that can be used in almost every research laboratory. [ABSTRACT FROM AUTHOR]

The difficult propagation of shrub and tree species and their extensive exposure to grazing threaten their abundance and lead to the necessity to find alternative means of propagation for these species. In vitro micropropagation techniques, viz., tissue culture, offer a promising tool for the rapid, cost-effective, and efficient propagation of different plant species. In the current study, a rapid and efficient in vitro multiplication protocol was developed for the micropropagation of Maerua crassifolia Forssk. Our results revealed that Murashige and Skoog (MS) medium with 7.5 µM of 6-benzylaminopurine (BA) and 1.0 µM of 1-naphthaleneacetic acid (NAA) led to the highest shoot formation (13.9 shoots per explant in 85.7% of the cultivated hypocotyls) among all other treatments. The best in vitro root formation was obtained on half-strength MS medium with 1.0 µM of indole 3-butyric acid (IBA) as 94.1% of the cultivated shoots formed 6.8 roots per microshoot on average. Ninety percent of the rooted plantlets were successfully acclimatized and are currently growing in the botanical garden of the Botany and Microbiology Department, King Saud University, Riyadh, Saudi Arabia. The genetic fidelity of the micropropagated plants was authenticated via flow cytometry. The results of the current study explained a simple, cost-effective, and efficient protocol for the micropropagation of the endangered M. crassifolia trees. [ABSTRACT FROM AUTHOR]

SUMMARY: The formation of adventitious roots (ARs) derived from hypocotyl is the most important morphological adaptation to waterlogging stress in Cucumis sativus (cucumber). Our previous study showed that cucumbers with the gene CsARN6.1, encoding an AAA ATPase domain‐containing protein, were more tolerant to waterlogging through increased AR formation. However, the apparent function of CsARN6.1 remained unknown. Here, we showed that the CsARN6.1 signal was predominantly observed throughout the cambium of hypocotyls, where de novo AR primordia are formed upon waterlogging treatment. The silencing of CsARN6.1 expression by virus‐induced gene silencing and CRISPR/Cas9 technologies adversely affects the formation of ARs under conditions of waterlogging. Waterlogging treatment significantly induced ethylene production, thus upregulating CsEIL3 expression, which encodes a putative transcription factor involved in ethylene signaling. Furthermore, yeast one‐hybrid, electrophoretic mobility assay and transient expression analyses showed that CsEIL3 binds directly to the CsARN6.1 promoter to initiate its expression. CsARN6.1 was found to interact with CsPrx5, a waterlogging‐responsive class‐III peroxidase that enhanced H2O2 production and increased AR formation. These data provide insights into understanding the molecular mechanisms of AAA ATPase domain‐containing protein and uncover a molecular mechanism that links ethylene signaling with the formation of ARs triggered by waterlogging. Significance Statement: The AAA ATPase domain‐containing protein CsARN6.1 is required for waterlogging stress tolerance, where it regulates adventitious root (AR) formation. However, the functional relevance of this gene remained unknown. Our results reveal that in cucumber, a CsEIL3‐CsARN6.1 regulatory module confers AR formation through H2O2 production, mediated by CsPrx5. [ABSTRACT FROM AUTHOR]

Plant organogenesis requires matching the available metabolic resources to developmental programs. In Arabidopsis, the root system is determined by primary root‐derived lateral roots (LRs), and adventitious roots (ARs) formed from non‐root organs. Lateral root formation entails the auxin‐dependent activation of transcription factors ARF7, ARF19, and LBD16. Adventitious root formation relies on LBD16 activation by auxin and WOX11. The allocation of shoot‐derived sugar to the roots influences branching, but how its availability is sensed for LRs formation remains unknown. We combine metabolic profiling with cell‐specific interference to show that LRs switch to glycolysis and consume carbohydrates. The target‐of‐rapamycin (TOR) kinase is activated in the lateral root domain. Interfering with TOR kinase blocks LR initiation while promoting AR formation. The target‐of‐rapamycin inhibition marginally affects the auxin‐induced transcriptional response of the pericycle but attenuates the translation of ARF19, ARF7, and LBD16. TOR inhibition induces WOX11 transcription in these cells, yet no root branching occurs as TOR controls LBD16 translation. TOR is a central gatekeeper for root branching that integrates local auxin‐dependent pathways with systemic metabolic signals, modulating the translation of auxin‐induced genes. Synopsis: Shoot‐derived sugar promotes lateral root formation, but the mechanism through which it influences cell differentiation in this context is not well understood. Here, we learn that TOR kinase mediates lateral root formation by inducing the translation of lateral root‐promoting transcription factor transcripts in a sugar‐dependent manner.Lateral root formation is an important consumer of shoot‐derived carbon.Pericycle activation requires shoot‐derived carbohydrates and TOR.TOR promotes the translation of transcription factors ARF19, ARF7, and LBD16.TOR suppresses non‐canonical primary root branching by inhibiting WOX11 expression. [ABSTRACT FROM AUTHOR]

An appropriate planting density could realize the maximum yield potential of crops, but the mechanism of sweet potato storage root formation in response to planting density is still rarely investigated. Four planting densities, namely D15, D20, D25, and D30, were set for 2-year and two-site field experiments to investigate the carbohydrate and lignin metabolism in potential storage roots and its relationship with the storage root number, yield, and commercial characteristics at the harvest period. The results showed that an appropriate planting density (D20 treatment) stimulated cambium cell differentiation, which increased carbohydrate accumulation and inhibited lignin biosynthesis in potential storage roots. At canopy closure, the D20 treatment produced more storage roots, particularly developing ones. It increased the yield by 10.18–19.73% compared with the control D25 treatment and improved the commercial features by decreasing the storage root length/diameter ratio and increasing the storage root weight uniformity. This study provides a theoretical basis for the high-value production of sweet potato. [ABSTRACT FROM AUTHOR]

Auxin distribution is essential for determining root developmental patterns. The formation of lateral roots and constitutive aerenchyma, which is a gas space developed through cell death, is regulated by auxin in rice (Oryza sativa). However, it is unclear whether the involvement of auxin in constitutive aerenchyma formation is conserved in other species. In this study, we found that constitutive aerenchyma formation was regulated by auxin in the nodal roots of Zea nicaraguensis, a wild relative of maize (Zea mays ssp. mays) grown naturally on frequently flooded coastal plains. Subsequent gravistimulation (root rotation) experiments showed opposite patterns of aerenchyma and lateral root formation. Lateral root formation on the convex side of rotated roots is known to be stimulated by a transient increase in auxin level in the pericycle. We found that aerenchyma formation was accelerated in the cortex on the concave side of the rotated nodal roots of Z. nicaraguensis. A cortex-specific expression analysis of auxin-responsive genes suggested that the auxin level was higher on the concave side than on the convex side. These results suggest that asymmetric auxin distribution underlies the regulation of aerenchyma and lateral root formation in the nodal roots of Z. nicaraguensis. As aerenchyma reduces the respiratory cost of the roots, constitutive aerenchyma on the concave side of the nodal root may balance resource allocation, thereby contributing to the uptake of water and nutrients by newly formed lateral roots. Our study provides insights into auxin-dependent asymmetric root patterning such as that of gravistimulation and hydropatterning response. [ABSTRACT FROM AUTHOR]

Wild plant species are of great interest as a source of pharmacologically valuable compounds but a great number of them are endemic and/or endangered ones. Modern plant biotechnology can provide reliable methods for their utilization without disturbing natural populations. In vitro culture methods for Rhodiola species are being intensively developed to include them into various biotechnological programmes. Aim. Development of a protocol for direct Rhodiola rosea L. plant regeneration from leaf explants. Methods. The leaves of R. rosea aseptically growing plants were used as the explants. Several variants of Murashige and Skoog (1962) agar-solidified culture medium supplemented with different combinations of auxins (1-naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D)) and cytokinins (kinetin and 6-benzylaminopurine (BAP)) were estimated as potential regeneration-inducing media. Regeneration frequency was calculated as the percentage of leaves that produced shoots. Results. The use of MS medium supplemented with 2.5 mg/l BAP and 1.0 mg/l 2,4-D allowed inducing shoot formation with 100% frequency. An increase in the 2,4-D content up to 2.5 mg/l and decrease in BAP content to 1.0 mg/l resulted in decreasing of the regeneration frequency to 62.5%. Regeneration frequency was 25% and 62%, respectively, on the media containing 1.0 mg/l kinetin + 2.5 mg/l 2,4-D and 2.5 mg/l kinetin + 1.0 mg/l 2,4-D. Conclusions. R. rosea leaf explants have demonstrated high regeneration capacity with the use of the studied combinations of plant growth regulators. MS medium supplemented with 2.5 mg/l BAP and 1.0 mg/l 2,4-D allowed inducing shoot regeneration in leaf explants with the frequency of 100%. The frequency of regeneration was lower in the case of substitution of BAP for kinetin. The other types of morphogenesis (formation of adventitious roots and/or callus) were also observed. [ABSTRACT FROM AUTHOR]

In order to study the effect of plant growth regulators on the rooting of Vitex quinata, the cuttings of semilignified Vitex quinata were treated with different kinds, concentrations and soaking time of plant growth regulators to study the rooting and physiological and biochemical changes of cuttings. The results showed that there were significant differences in rooting rate, average root length, longest root length, average root number, average root diameter and longest root system diameter among different plant growth regulators. Through the comprehensive evaluation of membership function method, the membership function value of the treatment with NAA concentration of 200mg/L and soaking time of 2h was the highest, reaching 0.88. In the process of rooting, the content of soluble sugar and soluble protein showed a trend of ‘decline-rise-decline’. The activities of SOD, POD and PPO in the treatment group were higher than those in CK treatment. In the root primordial induction stage, the activities of SOD and POD increased, while in the adventitious root formation stage, the activities of SOD and PPO continued to increase and the activities of POD decreased. In the adventitious root elongation stage, the activities of POD increased and the activities of SOD and PPO decreased. NAA concentration of 200 mg/L and soaking time of 2 h were the most suitable treatments for cutting rooting of Vitex quinata, which can change the nutrient content of cuttings, improve the enzyme activity during rooting and promote the growth of rooting. [ABSTRACT FROM AUTHOR]

In Arabidopsis, the small signaling peptide (peptide hormone) RALF34 is involved in the gene regulatory network of lateral root initiation. In this study, we aimed to understand the nature of the signals induced by RALF34 in the non-model plant cucumber (Cucumis sativus), where lateral root primordia are induced in the apical meristem of the parental root. The RALF family members of cucumber were identified using phylogenetic analysis. The sequence of events involved in the initiation and development of lateral root primordia in cucumber was examined in detail. To elucidate the role of the small signaling peptide CsRALF34 and its receptor CsTHESEUS1 in the initial stages of lateral root formation in the parental root meristem in cucumber, we studied the expression patterns of both genes, as well as the localization and transport of the CsRALF34 peptide. CsRALF34 is expressed in all plant organs. CsRALF34 seems to differ from AtRALF34 in that its expression is not regulated by auxin. The expression of AtRALF34, as well as CsRALF34, is regulated in part by ethylene. CsTHESEUS1 is expressed constitutively in cucumber root tissues. Our data suggest that CsRALF34 acts in a non-cell-autonomous manner and is not involved in lateral root initiation in cucumber. [ABSTRACT FROM AUTHOR]

Plants can adapt to the spatial heterogeneity of soil nutrients by changing the morphology and architecture of the root system. Here, we explored the role of auxin in the response of sweetpotato roots to potassium (K+) deficiency stress. Two sweetpotato cultivars, Xushu 32 (low-K-tolerant) and Ningzishu 1 (low-K-sensitive), were cultured in low K+ (0.1 mmol L−1, LK) and normal K+ (10 mmol L−1, CK) nutrient solutions. Compared with CK, LK reduced the dry mass, K+ content, and K+ accumulation in the two cultivars, but the losses of Xushu 32 were smaller than those of Ningzishu 1. LK also affected root growth, mainly impairing the length, surface area, forks number, and crossings number. However, Xushu 32 had significantly higher lateral root length, density, and surface area than Ningzishu 1, closely related to the roots' higher indole-3-acetic acid (IAA) content. According to the qPCR results, Xushu 32 synthesized more IAA (via IbYUC8 and IbTAR2) in leaves but transported and accumulated in roots through polar transport (via IbPIN1, IbPIN3, and IbAUX1). It was also associated with the upregulation of auxin signaling pathway genes (IbIAA4 and IbIAA8) in roots. These results imply that IAA participates in the formation of lateral roots and the change in root architecture during the tolerance to low K+ stress of sweetpotato, thus improving the absorption of K+ and the formation of biomass. [ABSTRACT FROM AUTHOR]

This study aimed to explore the effects of different concentrations of indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), and indene-naphthaleneacetic acid (ABT-1) on the rooting and dynamic changes of the endogenous hormone content of Australian Mulberry (vegetable Mulberry) and Kirin mulberry (Fruit Mulberry) hardwood cuttings. As exhibited by the results, the rooting process of both vegetable mulberry and fruit mulberry could be divided into three stages, namely the initiation stage (1–18 days), the callus formation stage (18–28 days), and the adventitious root formation and elongation stage (28–48 days). The two treatments with 1000 mg·L−1 ABT-1 and 500 mg·L−1 ABT-1 achieved the highest rooting efficiencies of vegetable mulberry and fruit mulberry, significantly higher than those of other treatments (p < 0.01), with average rooting rates of 63.3% and 68.7%, and rooting efficiency indices of 25.3 and 34.3, respectively. During the rooting process, the contents of endogenous IAA and zeatin riboside (ZR) and the ratios of IAA/ABA and IAA/ZR presented a trend of decreasing before increasing, while the abscisic acid (ABA) and jasmonic acid (JA) contents exhibited a trend of increasing before decreasing, and the gibberellin (GA3), strigolactone (SL), and IBA contents showed a continuous decreasing trend. Hence, ABT-1 was effective in inducing the synthesis of IAA, IBA, JA, and SL, reducing the contents of ABA, ZR, and GA3, and promoting the rooting of vegetable mulberry and fruit mulberry cuttings. For fruit mulberry and vegetable mulberry cuttings, the optimal concentrations of ABT-1 were 500 mg·L−1 and 1000 mg·L−1, respectively, demonstrating applicability for the efficient propagation of Morus alba L. cuttings. [ABSTRACT FROM AUTHOR]

Crown roots are the main components of the fibrous root system in cereal crops and play critical roles in plant adaptation; however, the molecular mechanisms underlying their formation in wheat (Triticum aestivum) have not been fully elucidated. In this study, we identified a wheat basic helix-loop-helix (bHLH) protein, TabHLH123, that interacts with the essential regulator of crown root initiation, MORE ROOT in wheat (TaMOR). TabHLH123 is expressed highly in shoot bases and roots. Ectopic expression of TabHLH123 in rice resulted in more roots compared with the wild type. TabHLH123 regulates the expression of genes controlling crown-root development and auxin metabolism, responses, and transport. In addition, we analysed the nucleotide sequence polymorphisms of TabHLH123 s in the wheat genome and identified a superior haplotype, TabHLH123-6B , that is associated with high root dry weight and 1000-grain weight, and short plant height. Our study reveals the role of TabHLH123 in controlling the formation of crown roots and provides beneficial insights for molecular marker-assisted breeding in wheat. [ABSTRACT FROM AUTHOR]

Cuttage propagation involves adventitious root formation induced by auxin. In our previous study, Larix kaempferi BABY BOOM 1 (LkBBM1), which is known to regulate adventitious root formation, was affected by auxin. However, the relationship between LkBBM1 and auxin remains unclear. Auxin response factors (ARFs) are a class of important transcription factors in the auxin signaling pathway and modulate the expression of early auxin-responsive genes by binding to auxin response elements. In the present study, we identified 14 L. kaempferi ARFs (LkARFs), and found LkARF7 and LkARF19 bound to LkBBM1 promoter and enhanced its transcription using yeast one-hybrid, ChIP-qPCR, and dual-luciferase assays. In addition, the treatment with naphthalene acetic acid promoted the expression of LkARF7 and LkARF19. We also found that overexpression of these two genes in poplar promoted adventitious root formation. Furthermore, LkARF19 interacted with the DEAD-box ATP-dependent RNA helicase 53-like protein to form a heterodimer to regulate adventitious root formation. Altogether, our results reveal an additional regulatory mechanism underlying the control of adventitious root formation by auxin. Overexpression of the transcription factors LkARF7 and LkARF19 promote adventitious root (AR) formation in a heterologous poplar model by positively regulating LkBBM1, providing further insight into the mechanisms of AR development. [ABSTRACT FROM AUTHOR]

Background: Alfalfa (Medicago sativa L.) as an important legume plant can quickly produce adventitious roots (ARs) to form new plants by cutting. But the regulatory mechanism of AR formation in alfalfa remains unclear. Results: To better understand the rooting process of alfalfa cuttings, plant materials from four stages, including initial separation stage (C stage), induction stage (Y stage), AR primordium formation stage (P stage) and AR maturation stage (S stage) were collected and used for RNA-Seq. Meanwhile, three candidate genes (SAUR, VAN3 and EGLC) were selected to explore their roles in AR formation. The numbers of differentially expressed genes (DEGs) of Y-vs-C (9,724) and P-vs-Y groups (6,836) were larger than that of S-vs-P group (150), indicating highly active in the early AR formation during the complicated development process. Pathways related to cell wall and sugar metabolism, root development, cell cycle, stem cell, and protease were identified, indicating that these genes were involved in AR production. A large number of hormone-related genes associated with the formation of alfalfa ARs have also been identified, in which auxin, ABA and brassinosteroids are thought to play key regulatory roles. Comparing with TF database, it was found that AP2/ERF-ERF, bHLH, WRKY, NAC, MYB, C2H2, bZIP, GRAS played a major regulatory role in the production of ARs of alfalfa. Furthermore, three identified genes showed significant promotion effect on AR formation. Conclusions: Stimulation of stem basal cells in alfalfa by cutting induced AR production through the regulation of various hormones, transcription factors and kinases. This study provides new insights of AR formation in alfalfa and enriches gene resources in crop planting and cultivation. [ABSTRACT FROM AUTHOR]

Aquilaria is known to produce agarwood, but its natural population is declining. Apart from being recalcitrant, not all Aquilaria trees are agarwood producers, hence yield is not guaranteed in plantations established from seedlings originated from seeds. Since cloning can produce progenies with similar genetic quality as parent trees, this study evaluated the effect of various leaf trimmings, indole-3-butyric acid (IBA) doses, and their interaction in rooting induction of cuttings from mature Aquilaria cumingiana. Analysis of variance revealed a significant (p < 0.001) increase in most of the rooting parameters with increasing leaf surface areas (except on shoot length) and IBA concentrations (aside from shoot length, percentage of survival and percentage of callus). Interaction between IBA (1000 ppm) and cuttings, with half of the leaf surface trimmed, detected the highest rooting percentage (46.67%, p < 0.001), number of roots (1.16, p < 0.05), average root length (14.05 mm, p < 0.001), number of secondary roots (3.49, p < 0.001) and length of the longest roots (18.56 mm, p < 0.001). Correlations among root traits (r2 = 0.11-0.95), between rooting trait and cutting size (r2 = - 0.09-0.09), and among cutting sizes (r2 = 0.69-0.96) were found to be highly significant (p < 0.001). The results showed potential to produce high agarwood yielding A. cumingiana using low-cost cloning technique. [ABSTRACT FROM AUTHOR]

Adventitious root (AR) formation plays an important role in vegetatively propagated plants. Cytokinin (CK) inhibits AR formation, but the molecular mechanisms driving this process remain unknown. In this study, we confirmed that CK content is related to AR formation and further revealed that a high auxin/CK ratio was beneficial to AR formation in apple (Malus domestica). A correlation between expression of CK-responsive TEOSINTE BRANCHED1 , CYCLOIDEA , and PCF17 (MdTCP17) and AR formation in response to CK was identified, and overexpression of MdTCP17 in transgenic apple inhibited AR formation. Yeast two-hybrid, bimolecular fluorescence complementation, and co-immunoprecipitation assays revealed an interaction between MdTCP17 and WUSCHEL-RELATED HOMEOBOX11 (MdWOX11), and a significant correlation between the expression of MdWOX11 and AR ability. Overexpression of MdWOX11 promoted AR primordium formation in apple, while interference of MdWOX11 inhibited AR primordium production. Moreover, a positive correlation was found between MdWOX11 and LATERAL ORGAN BOUNDARIES DOMAIN29 (MdLBD29) expression, and yeast one-hybrid, dual luciferase reporter, and ChIP-qPCR assays verified the binding of MdWOX11 to the MdLBD29 promoter with a WOX-box element in the binding sequence. Furthermore, MdTCP17 reduced the binding of MdWOX11 and MdLBD29 promoters, and coexpression of MdTCP17 and MdWOX11 reduced MdLBD29 expression. Together, these results explain the function and molecular mechanism of MdTCP17 -mediated CK inhibition of AR primordium formation, which could be used to improve apple rootstocks genetically. [ABSTRACT FROM AUTHOR]

Waterlogging is severe abiotic stress during mung bean (Vigna radiata (L.) R. Wilczek var. radiata) production. Waterlogging impacts yield loss for the legume crop by around 40%-70%, depending on the severity and duration of the waterlogging. In total, 107 collected mung bean varieties were evaluated under managed waterlogging. The F2 population from crossing between waterlogging-tolerant and -susceptible mung bean varieties were screened under waterlogging conditions. Morphological responses to the waterlogging were recorded. Correlation and path coefficient analyses were used to identify essential traits for waterlogging tolerance and seed yield potential under water stress. Mung bean varieties in clusters 5 and 6 were high waterlogging tolerance with survival rates of 66.66% and 61.11%, respectively. Of 199 F2 lines from crossings between the Kamphaeng Sean2 and W162, 20 lines presented high waterlogging tolerance. The injury score was negatively correlated with the number of leaves at the final date of waterlogging (-0.845) and 1 wk after terminating the waterlogging (-0.885). At the final date of waterlogging condition, the number of leaves and leaf greenness stability index directly affected leaf injury at -0.5928 and -0.4385. One week after waterlogging termination, only the number of leaves affected the leaf injury at -0.8599. The number of leaves directly affected seed yield components at 0.6534 and higher than the direct effect of the other traits. Thus, the number of leaves was a suitable morphological parameter along with the injury score for selecting waterlogging tolerance. The number of leaves was a suitable parameter for selecting high seed yield potential under waterlogging conditions. [ABSTRACT FROM AUTHOR]

Background: Okra is an economically important crop grown in tropical, subtropical and Mediterranean countries. It belongs to the Malvaceae family. This study aims to propagate this plant on a large scale by its in vitro regeneration and obtain healthy plants. Methods: Okra is micropropagated from nodal and shoot apex explants excised from 21-day-old seedlings. Isolated explants were then cultured in Murashige and Skoog medium without plant growth regulators at a temperature of 27C, a photoperiod of 16-h light/8-h dark and a light intensity of 3000 lux. Leaves formation occurred after one week of culture, followed after 10 days by rooting formation. Result: The plantlets formed, grew and developed and after one month of cultivation under the same conditions, a difference in the length of the shoot was recorded, measuring 10.12 cm in the plantlets obtained from nodal segments and 7.37 cm in the plantlets from shoot apices. There was also a minimal difference in rooting, which was well observed in plantlets regenerated from nodal explants. Both types of explants developed into complete plantlets in only one month. Then, they were transferred to the greenhouse for acclimatisation. Using this technique, the in vitro production of plants is relatively simple, fast and less expensive. [ABSTRACT FROM AUTHOR]

Objective To investigate whether there is a difference in apical resorption activity during the development of roots in response to mechanical force in vivo. Methods Maxillary first molars (M1) from postnatal day (PN) 21 and PN35 male rats were selected as representatives of the root-developing and root-completing groups, respectively. A mechanical force of 3 cN was applied to M1 on PN21 and PN35, and the maxilla was collected on PN28 and PN42. Odontoclastogenesis and root morphology were investigated using micro-focus X-ray computed tomography, followed by immunohistochemistry and quantitative real-time polymerase chain reaction to clarify root resorption activity. Results Development of the mesiobuccal root (MBR) preceded the mesial root (MR). In the PN28 force application (FA) group, the dentine was bent, but the histology, including Hertwig's epithelial root sheath (HERS), was intact. No odontoclasts and resorption lacunae were found in the apical area of the MRs, and only lateral root resorption was observed. External apical root resorption (EARR) was observed in the MR of PN42 (FA) and in the MBR of both PN28 (FA) and PN42 (FA). The expression of osteopontin changed accordingly. No significant change occurred in osteoprotegerin or receptor activator of nuclear factor-κB ligand expression in the MRs of the PN28 (FA) group. Limitations Our animal model did not adequately simulate the clinical process of tooth movement in humans. Conclusions Force application delayed HERS dissociation on the compression side of the developing roots, leading to inhibitory effects on cementogenesis, which resulted in decreased odontoclast differentiation and prevention of EARR. [ABSTRACT FROM AUTHOR]