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Summary: Abscission is the shedding of plant organs in response to developmental and environmental cues. Abscission involves cell separation between two neighboring cell types, residuum cells (RECs) and secession cells (SECs) in the floral abscission zone (AZ) in Arabidopsis thaliana. However, the regulatory mechanisms behind the spatial determination that governs cell separation are largely unknown.The class I KNOTTED‐like homeobox (KNOX) transcription factor BREVIPEDICELLUS (BP) negatively regulates AZ cell size and number in Arabidopsis. To identify new players participating in abscission, we performed a genetic screen by activation tagging a weak complementation line of bp‐3. We identified the mutant ebp1 (enhancer of BP1) displaying delayed floral organ abscission.The ebp1 mutant showed a concaved surface in SECs and abnormally stacked cells on the top of RECs, in contrast to the precisely separated surface in the wild‐type. Molecular and histological analyses revealed that the transcriptional programming during cell differentiation in the AZ is compromised in ebp1. The SECs of ebp1 have acquired REC‐like properties, including cuticle formation and superoxide production.We show that SEPARATION AFFECTING RNA‐BINDING PROTEIN1 (SARP1) is upregulated in ebp1 and plays a role in the establishment of the cell separation layer during floral organ abscission in Arabidopsis. [ABSTRACT FROM AUTHOR]

Duplicated genes are thought to follow one of three evolutionary trajectories that resolve their redundancy: neofunctionalization, subfunctionalization, or pseudogenization. Differences in expression patterns have been documented for many duplicated gene pairs and interpreted as evidence of subfunctionalization and a loss of redundancy. However, little is known about the functional impact of such differences and about their molecular basis. Here, we investigate the genetic and molecular basis for the partial loss of redundancy between the two BLADE-ON-PETIOLE genes BOP1 and BOP2 in red shepherd's purse (Capsella rubella) compared to Arabidopsis (Arabidopsis thaliana). While both genes remain almost fully redundant in A. thaliana, BOP1 in C. rubella can no longer ensure wild-type floral organ numbers and suppress bract formation, due to an altered expression pattern in the region of the cryptic bract primordium. We use two complementary approaches, transgenic rescue of A. thaliana atbop1 atbop2 double mutants and deletions in the endogenous AtBOP1 promoter, to demonstrate that several BOP1 promoter regions containing conserved noncoding sequences interact in a nonadditive manner to control BOP1 expression in the bract primordium and that changes in these interactions underlie the evolutionary divergence between C. rubella and A. thaliana BOP1 expression and activity. Similarly, altered interactions between cis-regulatory regions underlie the divergence in functional promoter architecture related to the control of floral organ abscission by BOP1. These findings highlight the complexity of promoter architecture in plants and suggest that changes in the interactions between cis-regulatory elements are key drivers for evolutionary divergence in gene expression and the loss of redundancy. Evolutionary changes affecting the interactions between cis-regulatory elements in the promoter of duplicated development genes partially resolve their redundancy in Capsella rubella. [ABSTRACT FROM AUTHOR]

The flowering time and plant architecture of Brassica napus were significantly associated with yield. In this study, we found that the BREVIPEDICELLUS/KNAT1(BP) gene regulated the flowering time and plant architecture of B. napus. However, the precise regulatory mechanism remains unclear. We cloned two homologous BP genes, BnaBPA03 and BnaBPC03, from B. napus Xiaoyun. The protein sequence analysis showed two proteins containing conserved domains KNOX I, KNOX II, ELK, and HOX of the KONX protein family. The CRISPR/Cas9 knockout lines exhibited early budding and flowering time, coupled with floral organ abscission earlier and a larger leaf angle. On the contrary, overexpression plants displayed a phenotype that was the inverse of these characteristics. Furthermore, we observed upregulation of gibberellin and ethylene biosynthesis genes, as well as floral integrator genes in knocked‐out plants. The results revealed that BnaBPs play a role in flowering time, floral organ abscission, and leaf angle as well as germination processes mediated. Additionally, BnaBPs exerted an impact on the biosynthesis pathways of ethylene and GA. [ABSTRACT FROM AUTHOR]

Jalisco is one of the main areas in Mexico that produces avocados (Persea americana Miller), and the adults of Euphoria basalis (Gory & Percheron) have been detected on avocado inflorescences where they feed and cause the flowers to fall prematurely. To our knowledge, this is the first report of the association of this species with P. americana trees in Mexico. [ABSTRACT FROM AUTHOR]

In the sixteenth and seventeenth centuries, the trade in and cultivation of exotic plant life proliferated at a rapid rate. Horticulturalists analogized plant acclimatization to human travel and acculturation, arguing that transplantation could ameliorate both species. Despite anxieties surrounding the influence of foreign environments, unfamiliar soil was thought to bring about "civility" and provoke both plants and humans to shed their "ill qualit[ies]." As I show, horticulturalists, such as John Parkinson and John Evelyn, distinguish plants that embody this myth from those that resist foreign soil, attributing their decline to their affective dispositions, their "peevish" or "impatient" temperaments, for example. Not only does this anthropomorphic impulse ignore the harsh climatological conditions to which plants were exposed, but it also contributes to an emerging racial discourse that differentiates human populations by their perceived cultivability, whether or not they can become more "civil." I argue that English polemicists, writing on the supposed savagery of the Irish, reappropriate this fantasy to authorize subjugation and forcible displacement. In drawing attention to the horticultural rhetoric that justified these imperial ventures, this essay proffers new avenues for examining the ideologies that underwrote colonial violence in Africa, the Indian subcontinent, and the Americas. [R.B.] [ABSTRACT FROM AUTHOR]

Mitogen-activated protein kinase (MAPK) cascades have been discovered to play a fundamental role in regulating organ abscission. However, the identity of protein substrates targeted by MAPK cascades, as well as whether the role of MAPK protein cascades in the abscission process is conserved across different plant species, remain unknown. Here, the role of homologs of MPK3 and MPK6 in regulating fruit abscission were characterized in litchi. Ectopic expression of LcMPK3 or LcMPK6 in Arabidopsis mpk3 mpk6 mutant rescued the deficiency in floral organ abscission, while silencing of LcMPK3 or LcMPK6 in litchi significantly decreased fruitlet abscission. Importantly, a total of 49 proteins interacting with LcMPK3 were identified through yeast two-hybrid screening, including two components of the MAPK signaling cascade, five transcription factors, and two aquaporins. Furthermore, the interaction between LcMPK3/6 with LcBZR1/2, core components in brassinosteroids signaling that suppress litchi fruitlet abscission, was confirmed using in vitro and in vivo assays. Moreover, phos-tag assays demonstrated that LcMPK3/6 could phosphorylate LcBZR1/2, with several phosphorylation residues identified. Together, our findings suggest that LcMPK3 and LcMPK6 play a positive regulatory role in fruitlet abscission in litchi, and offer crucial information for the investigation of mechanisms underlying MPK3/6-mediated organ abscission in plants. [ABSTRACT FROM AUTHOR]

Background: Flower bud/s, flower/s and fruit/pod/s abscission is one of the momentous bottlenecks in pulses in general and pigeonpea in particular, resulting in poor reproductive efficiency. Abscission occurs both before and after fertilization. Knowledge on nature and extent of genetic variation available in the genotypes help breeders for planning breeding programmes to identify genotypes that retain maximum flowers hence increase pod set. Methods: A total of 19 advanced stabilized breeding lines including 2 local checks (GRG-811 and TS-3R) were evaluated in randomized block design (RBD) with two replications in rain fed and irrigated condition at Zonal Agricultural Research Station (ZARS), Kalaburagi, during kharif 2018. Genetic variation for flower production, abscission and pollen load were studied and interpreted. Result: The genotypes viz., RIL-63, RIL-59, GRG-152 and KRG-224 showed good number of pods set per plant in rainfed condition and 3 Genotypes WRP-R-29-4, KRG-224 and ICPL-15017 in irrigated condition. The genotype KRG-224 Sets more pods under both conditions. Pollen grains load was more in undropped flower compared to dropped flower. [ABSTRACT FROM AUTHOR]

Simple Summary: The ancestors of modern peanuts underwent genetic transformation under natural conditions millions of years ago to acquire genes for opine synthesis. Eventually, the genes for the agropine synthesis pathway were lost in most of the studied samples or remained in the form of small fragments. Conversely, the genes for cucumopine synthesis remained intact and functional in most species, probably due to being under a regime of stabilizing selection. The variability of natural transgenes can be used in phylogenetic studies. Naturally transgenic plants are plants that have undergone Agrobacterium-mediated transformation under natural conditions without human involvement. Among Arachis hypogaea L., A. duranensis Krapov. & W.C. Greg, A. ipaensis Krapov. & W.C. Greg, A. monticola Krapov. & Rigoni, and A. stenosperma Krapov. & W.C. Greg are known to contain sequences derived from the T-DNA of "Agrobacterium". In the present study, using molecular genetics and bioinformatic methods, we characterized natural transgenes in 18 new species from six sections of the genus Arachis. We found that small fragments of genes for enzymes of the agropine synthesis pathway were preserved only in some of the studied samples and were lost in the majority of the species during evolution. At the same time, genes, similar to cucumopine synthases (cus-like), remained intact in almost all of the investigated species. In cultivated peanuts, they are expressed in a tissue-specific manner. We demonstrated the intraspecific variability of the structure and expression of the cus-like gene in cultivated peanuts. The described diversity of gene sequences horizontally transferred from Agrobacterium to plants helps to shed light on the phylogeny of species of the genus Arachis and track possible hybridization events. Data on the ability of certain species to hybridize are useful for planning breeding schemes aimed at transferring valuable traits from wild species into cultivated peanuts. [ABSTRACT FROM AUTHOR]

Many examples of phenotypic modifications resulting from high‐elevation adaptation have been documented, however, the underlying processes responsible for these modifications and whether the continuity of the adaptation process remain elusive, particularly in plants. The alpine plants distributed along wide elevational gradients provide an ideal system to address this question. Here, we collected transcriptomes from multiple tissues of three species with different elevations (~1500, ~2500, and ~3600 m in the Hengduan Mountains, Southwest China) in two genera Fargesia and Yushania of alpine bamboos, respectively, and conducted evolutionary and expressional analyses. Results showed that high‐elevation adaptation emerged earlier in the evolutionary history of both genera and evolved continuously as the elevation increased. Moreover, convergence of genetic changes was observed in the two genera, with amounts of candidate genes responsible for high‐elevation adaptation identified under positive selection. Overall, our study provides an empirical example and valuable genetic resource for further investigation of high‐elevation adaptation in plants and sheds new light on how plants adapting to high‐elevation environments in a biodiversity hotspot. [ABSTRACT FROM AUTHOR]

JOINTLESS (J) was isolated in tomato (Solanum lycopersicum) from mutants lacking a flower pedicel abscission zone (AZ) and encodes a MADS-box protein of the SHORT VEGETATIVE PHASE/AGAMOUS-LIKE 24 subfamily. The loss of J function also causes the return to leaf initiation in the inflorescences, indicating a pivotal role in inflorescence meristem identity. Here, we compared jointless (j) mutants in different accessions that exhibit either an indeterminate shoot growth, producing regular sympodial segments, or a determinate shoot growth, due to the reduction of sympodial segments and causal mutation of the SELF-PRUNING (SP) gene. We observed that the inflorescence phenotype of j mutants is stronger in indeterminate (SP) accessions such as Ailsa Craig (AC), than in determinate (sp) ones, such as Heinz (Hz). Moreover, RNA-seq analysis revealed that the return to vegetative fate in j mutants is accompanied by expression of SP , which supports conversion of the inflorescence meristem to sympodial shoot meristem in j inflorescences. Other markers of vegetative meristems such as APETALA2c and branching genes such as BRANCHED 1 (BRC1a/b) were differentially expressed in the inflorescences of j (AC) mutant. We also found in the indeterminate AC accession that J represses homeotic genes of B- and C-classes and that its overexpression causes an oversized leafy calyx phenotype and has a dominant negative effect on AZ formation. A model is therefore proposed where J , by repressing shoot fate and influencing reproductive organ formation, acts as a key determinant of inflorescence meristems. [ABSTRACT FROM AUTHOR]

The abscission of floral organs and emergence of lateral roots in Arabidopsis is regulated by the peptide ligand inflorescence deficient in abscission (IDA) and the receptor protein kinases HAESA (HAE) and HAESA-like 2 (HSL2). During these cell separation processes, the plant induces defense-associated genes to protect against pathogen invasion. However, the molecular coordination between abscission and immunity has not been thoroughly explored. Here, we show that IDA induces a release of cytosolic calcium ions (Ca2+) and apoplastic production of reactive oxygen species, which are signatures of early defense responses. In addition, we find that IDA promotes late defense responses by the transcriptional upregulation of genes known to be involved in immunity. When comparing the IDA induced early immune responses to known immune responses, such as those elicited by flagellin22 treatment, we observe both similarities and differences. We propose a molecular mechanism by which IDA promotes signatures of an immune response in cells destined for separation to guard them from pathogen attack. [ABSTRACT FROM AUTHOR]

SUMMARY: Moving from sole cropping to intercropping is a transformative change in agriculture, contributing to yield. Soybeans adapt to light conditions in intercropping by adjusting the onset of reproduction and the inflorescence architecture to optimize reproductive success. Maize–soybean strip intercropping (MS), maize–soybean relay strip intercropping (IS), and sole soybean (SS) systems are typical soybean planting systems with significant differences in light environments during growth periods. To elucidate the effect of changes in the light environment on soybean flowering processes and provide a theoretical basis for selecting suitable varieties in various planting systems to improve yields, field experiments combining planting systems (IS, MS, and SS) and soybean varieties (GQ8, GX7, ND25, and NN996) were conducted in 2021 and 2022. Results showed that growth recovery in the IS resulted in a balance in the expression of TERMINAL FLOWER 1 (TFL1) and FLOWERING LOCUS T (FT) in the meristematic tissues of soybeans, which promoted the formation of new branches or flowers. IS prolonged the flowering time (2–7 days) and increased the number of forming flowers compared with SS (93.0 and 169%) and MS (67.3 and 103.3%) at the later soybean flowering stage. The higher carbon and nitrogen content in the middle and bottom canopies of soybean contributed to decreased flower abscission by 26.7 and 30.2%, respectively, compared with SS. Canopy light environment recovery promoted branch and flower formation and transformation of flowers into pods with lower flower‐pod abscission, which contributed to elevating soybean yields in late‐maturing and multibranching varieties (ND25) in IS. [ABSTRACT FROM AUTHOR]

Background: Cotton is an economically important crop. It is crucial to find an effective method to improve cotton yield, and one approach is to decrease the abscission of cotton bolls and buds. However, the lack of knowledge of the genetic and molecular mechanisms underlying cotton boll abscission traits has hindered genetic improvements. Results: Pearson's correlation analysis revealed a significant positive correlation between boll abscission rates 1 (AR1) and boll abscission rates 2 (AR2). A genome-wide association study was conducted on 145 loci that exhibited high polymorphism and were uniformly distributed across 26 chromosomes (pair). The study revealed 18, 46, and 62 markers that were significantly associated with boll abscission, fiber quality, and yield traits (P < 0.05), explaining 1.75%–7.13%, 1.16%–9.58%, and 1.40%–5.44% of the phenotypic variation, respectively. Notably, the marker MON_SHIN-1584b was associated with the cotton boll abscission trait, whereas MON_CGR5732a was associated with cotton boll abscission and fiber quality traits. Thirteen of the marker loci identified in this study had been previously reported. Based on phenotypic effects, six typical cultivars with elite alleles related to cotton boll abscission, fiber quality, and yield traits were identified. These cultivars hold great promise for widespread utilization in breeding programs. Conclusions: These results lay the foundation for understanding the molecular regulatory mechanism of cotton boll abscission and provide data for the future improvement of cotton breeding. [ABSTRACT FROM AUTHOR]

PIN-FORMED (PIN) proteins, which function as efflux transporters, play many crucial roles in the polar transportation of auxin within plants. In this study, the exogenous applications of auxin IAA and TIBA were found to significantly prolong and shorten the florescence of tree peony (Paeonia suffruticosa Andr.) flowers. This finding suggests that auxin has some regulatory influence in petal senescence and abscission. Further analysis revealed a total of 8 PsPINs distributed across three chromosomes, which could be categorized into two classes based on phylogenetic and structural analysis. PsPIN1, PsPIN2a-b, and PsPIN4 were separated into the "long" PIN category, while PsPIN5, PsPIN6a-b, and PsPIN8 belonged to the "short" one. Additionally, the cis-regulatory elements of PsPIN promoters were associated with plant development, phytohormones, and environmental stress. These genes displayed tissuespecific expression, and phosphorylation sites were abundant throughout the protein family. Notably, PsPIN4 displayed distinct and elevated expression levels in roots, leaves, and flower organs. Expression patterns among the abscission zone (AZ) and adjacent areas during various flowering stages and IAA treatment indicate that PsPIN4 likely influences the initiation of peony petal abscission. The PsPIN4 protein was observed to be co-localized on both the plasma membrane and the cell nucleus. The ectopic expression of PsPIN4 reversed the premature flower organs abscission in the Atpin4 and significantly protracted florescence when introduced to Col Arabidopsis. Our findings established a strong basis for further investigation of PIN gene biological functions, particularly concerning intrinsic relationship between PIN-mediated auxin polar. [ABSTRACT FROM AUTHOR]

Fruitlet calyx shedding in pear plants is apparently regulated via numerous pathways that involve both environmental triggers and phytohormones cues such as auxin. In this study, we found at 10 days after full bloom (DAFB) higher levels of indoleacetic acid (IAA) and tryptophan (Trp) in calyx persistence fruitlet (CPF) than calyx shedding fruitlet (CSF) of 'Danshan Suli' pear (Pyrus bretschneideri Rhed.). Consisting with this, the activity of indolealdehyde oxidase (IAAIdO), which promotes IAA synthesis, was remarkably increased, and that of peroxidase (POD), which degrades IAA, dropped markedly in CPF but not in CSF. Further, qRT-PCR results revealed that most of 31 PbrARFs (encoding auxin response factors) in Pyrus bretschneideri were highly expressed in CPF, whereas PbrARF4, PbrARF24 and PbrARF26 were significantly downregulated in CPF vis-a-vis CSF. Phylogenetic analysis revealed that 6 PbrARFs clustered in the group III, where PbrARF4 showed the closest affinity with AtARF1 that promotes organ abscission, indicating a putative role of PbrARF4 in mediating the process of calyx shedding in pear. In fact, the ectopic overexpression of PbrARF4 in Solanum lycopersicum resulted in an earlier-formed and deeper abscission layer (AL) in the transgenic plants, whose calyxes were more prone to wilt at the mature red stage (MR) compared with the control plants (wild-type). More importantly, expression levels of the abscission genes SlLS and SlCel2 in transgenic plants overexpressing PbrARF4 were significantly upregulated in comparation with the WT, whereas those of SlBI and SlTAPG2 were considerably inhibited. Further, PbrJOINTLESS and PbrIDA, the two genes related to calyx shedding in pear, were up-regulated more in CSF than CPF. The findings contribute to a better understanding of PbrARFs involved in fruitlet calyx shedding of pear, which could prove beneficial to improving the quality of pear fruit. [ABSTRACT FROM AUTHOR]

Avocado is an evergreen tree that exhibits protogynous dichogamy and displays a massive flower production, characterized by a high abscission of unfertilized flowers and developing fruitlets, ultimately leading to a low final fruit set. A common practice to improve avocado pollination involves introducing honey bee (Apis mellifera L.) hives during the flowering season. To evaluate the extent of inadequate pollination in avocado, the effect of different beehive densities on the percentage of flowers receiving pollen during the female flower stage was examined for seven years in an experimental orchard located in Southern Spain. A total of 17,288 flowers were observed under the microscope for this purpose. Additionally, pollen deposition was evaluated in five "Hass" avocado commercial orchards under different management strategies situated in the Malaga province (3960 flowers). The results obtained reveal that the percentage of flowers with pollen at the end of the female stage ranged from 2.85 (0.13% fruits retained at the end of June) in orchards without honey bee hives to 4.34 (0.11% fruits retained) in orchards in which 10 beehives per ha were placed. This percentage increased significantly to 13.79 after introducing 24 honey beehives per ha (0.21% fruits retained). Furthermore, the percentage of pollinated flowers in the commercial orchards remained below 15% even in those orchards in which pollen donors and honey bee hives were present. Thus, insufficient pollination could be considered as a primary limiting factor in avocado production under Mediterranean climates. Enhancing pollinator diversity and increasing their numbers could be a viable strategy to improve the percentage of avocado flowers receiving pollen during the female stage. [ABSTRACT FROM AUTHOR]

Tree peony (Paeonia suffruticosa Andrews) is a well-known ornamental plant with high economic value, but the short fluorescence is a key obstacle to its ornamental value and industry development. High temperature accelerates flower senescence and abscission, but the associated mechanisms are poorly understood. In this study, the tandem mass tag (TMT) proteome and label-free quantitative ubiquitome from tree peony cut flowers treated with 20 °C for 0 h (RT0), 20 °C or 28 °C for 60 h (RT60 or HT60) were examined based on morphological observation, respectively. Totally, 6970 proteins and 1545 lysine ubiquitinated (Kub) sites in 844 proteins were identified. Hydrophilic residues (such as glutamate and aspartate) neighboring the Kub sites were in preference, and 36.01% of the Kub sites were located on the protein surface. The differentially expressed proteins (DEPs) and Kub-DEPs in HT60 vs RT60 were mainly enriched in ribosomal protein, protein biosynthesis, secondary metabolites biosynthesis, flavonoid metabolism, carbohydrate catabolism, and auxin biosynthesis and signaling revealed by GO and KEGG analysis, accompanying the increase of endogenous abscisic acid (ABA) accumulation and decrease of endogenous indoleacetic acid (IAA) level. Additionally, the expression patterns of six enzymes (SAMS, ACO, YUC, CHS, ANS and PFK) putatively with Kub modifications were analyzed by proteome and real-time quantitative RT-PCR. The cell-free degradation assays showed PsSAMS and PsACO proteins could be degraded via the 26 S proteasome system in tree peony flowers. Finally, a working model was proposed for the acceleration of flower senescence and abscission by high temperature. In summary, all results contributed to understanding the mechanism of flower senescence induced by high temperature and prolonging fluorescence in tree peony. [ABSTRACT FROM AUTHOR]

Plant virus genomes encode proteins that are involved in replication, encapsidation, cell-to-cell, and long-distance movement, avoidance of host detection, counter-defense, and transmission from host to host, among other functions. Even though the multifunctionality of plant viral proteins is well documented, contemporary functional repertoires of individual proteins are incomplete. However, these can be enhanced by modeling tools. Here, predictive modeling of proteins encoded by the two genomic RNAs, i.e., RNA1 and RNA2, of grapevine fanleaf virus (GFLV) and their satellite RNAs by a suite of protein prediction software confirmed not only previously validated functions (suppressor of RNA silencing [VSR], viral genome-linked protein [VPg], protease [Pro], symptom determinant [Sd], homing protein [HP], movement protein [MP], coat protein [CP], and transmission determinant [Td]) and previously identified putative functions (helicase [Hel] and RNA-dependent RNA polymerase [Pol]), but also predicted novel functions with varying levels of confidence. These include a T3/T7-like RNA polymerase domain for protein 1AVSR, a short-chain reductase for protein 1BHel/VSR, a parathyroid hormone family domain for protein 1EPol/Sd, overlapping domains of unknown function and an ABC transporter domain for protein 2BMP, and DNA topoisomerase domains, transcription factor FBXO25 domain, or DNA Pol subunit cdc27 domain for the satellite RNA protein. Structural predictions for proteins 2AHP/Sd, 2BMP, and 3A? had low confidence, while predictions for proteins 1AVSR, 1BHel*/VSR, 1CVPg, 1DPro, 1EPol*/Sd, and 2CCP/Td retained higher confidence in at least one prediction. This research provided new insights into the structure and functions of GFLV proteins and their satellite protein. Future work is needed to validate these findings. [ABSTRACT FROM AUTHOR]

Flowers and pod abscission significantly reduces soybean yield. This study aims to identify the main signaling pathways and key candidate genes in soybean leaves that affect flower and pod abscission under shade conditions. This information will be useful for the localization and cloning of genes related to abscission. Two soybean cultivars with different abscission rates (Liaodou 32 and Shennongdou 28) were used in this experiment. The soybean leaves were subjected to 50% shading treatment and the transcriptome and metabolome was sequenced during the light-sensitive period. The effects of weak light at different growth stages on the metabolic pathways of soybean leaves and organ abscission were investigated by analyzing plant phenotype and physiological changes. The results showed that both two cultivars triggered the same molecular mechanism and similar metabolite accumulation mode by shading, but the regulations of the two cultivars were different. The key candidate genes identified for soybean flower and pod abscission caused by shading were DIV, MYB06, MYB44, MY1R1, MYBS3, WRKY6, WRK53, WRK70, WRK40, DOF14, CDF3, CDF2, GATA5, DREB3 and ERF3; the differentially expressed genes that caused the variation between the cultivars were SRM1, MYB16, WRK24, COL16, MYB61 and TRB1. The main metabolic pathways involved in soybean flower and pod abscission caused by shading were secondary metabolite biosynthesis pathway, metabolic pathway, cofactor biosynthesis pathway, phenylpropanoid biosynthesis pathway, flavonoid biosynthesis pathway, fatty acid biosynthesis pathway and amino acid biosynthesis pathway; the DEMs that caused the differences among the cultivars were carbon metabolism, glutathione metabolism, biotin metabolism, nucleotide metabolism, purine metabolism, plant hormone signaling, flavone and flavonol biosynthesis, lysine degradation, arginine and proline metabolism, amino sugars and nucleotide sugars metabolism, etc. In conclusion, shading treatment in the light-sensitive period of soybean changed the physiological response and gene expression level of leaves, inhibited carbohydrate metabolism and transport and biosynthesis of secondary metabolites, and thereby leading to increased competition and hormonal disruption, which promoted the abscission of soybean flowers/pods and reduced grain yield. [ABSTRACT FROM AUTHOR]

In agricultural production, rapid and accurate detection of peach blossom bloom plays a crucial role in yield prediction, and is the foundation for automatic thinning. The currently available manual operation-based detection and counting methods are extremely time-consuming and labor-intensive, and are prone to human error. In response to the above issues, this paper proposes a natural environment peach blossom detection model based on the YOLOv5 model. First, a cascaded network is used to add an output layer specifically for small target detection on the basis of the original three output layers. Second, a combined context extraction module (CAM) and feature refinement module (FSM) are added. Finally, the network clusters and statistically analyzes the range of multi-scale channel elements using the K-means++ algorithm, obtaining candidate box sizes that are suitable for the dataset. A novel bounding box regression loss function (SIoU) is used to fuse the directional information between the real box and the predicted box to improve detection accuracy. The experimental results show that, compared with the original YOLOv5s model, our model has correspondingly improved AP values for identifying three different peach blossom shapes, namely, bud, flower, and falling flower, by 7.8%, 10.1%, and 3.4%, respectively, while the final mAP value for peach blossom recognition increases by 7.1%. Good results are achieved in the detection of peach blossom flowering volume. The proposed model provides an effective method for obtaining more intuitive and accurate data sources during the process of peach yield prediction, and lays a theoretical foundation for the development of thinning robots. [ABSTRACT FROM AUTHOR]

Flacourtia indica (Burm.f.) Merr. is an important fruit and medicinal tree in Southern Africa. Efforts to achieve early fruiting have failed with juvenile propagules (planting materials) such as seed. Assessing rooting ability of mature (fruit bearing) F. indica stem cuttings is vital to attaining early fruiting, or precocious fruiting, which reduces the long juvenile phase experienced by many woody fruit trees when propagated from seeds (juvenile planting materials). The objectives of this study were to assess responses of mature stem cuttings to different application times of rooting hormone (Seradix® No. 2) and collection times of stem cuttings, and also to identify important pheno-phases in the yearly tree growth cycle of F. indica. A significantly higher rooting percentage (p < 0.001) was obtained with delayed Seradix® No. 2 application than with immediate application. Stem cuttings collected at flowering and leaf fall seasons were responsive to Seradix® No. 2 application, but all stem cuttings collected at fruiting time failed to produce roots. For stem cuttings collected during flowering time, immediate Seradix® application resulted in significantly (p = 0.0482) more roots than in stem cuttings subjected to delayed Seradix® application. The failure to produce roots of cuttings collected at fruiting time could be due to low sugars (carbohydrates) in the stem cuttings. The study concluded that the best time to collect stem cuttings from mature F. indica trees for rooting is either at flowering or leaf fall stages and that delayed Seradix® No. 2 application improves rooting of stem cuttings from mature F. indica trees. [ABSTRACT FROM AUTHOR]

A recent study published in the Journal of Experimental Botany has shed light on the role of awns, bristle-like structures found in grass species, in wheat crops. The researchers conducted a meta-analysis of data from breeding programs in the southeastern USA and found that awned wheat performs better than awnless wheat under heat stress conditions. Additionally, they discovered that awned wheat provides more year-to-year stability in yield, suggesting that awns could be an important trait for adapting crops to changing climatic conditions. The study highlights the potential benefits of further research on awns in wheat crops. [Extracted from the article]

The division of labor between florets responsible for reproduction and special functions occurs widely in condensed inflorescences. The capitulum of Albizia julibrissin consists of approximately 10–20 lateral flowers and usually one nectar‐secreting terminal flower; the two flower types are morphologically distinct, but the differences in reproductive function have not been revealed. To determine the differences in reproductive function between terminal and lateral flowers, we compared the ratio of terminal and lateral flowers at the flowering and young pod stages. Additionally, ovule number, stigma size, polyad size, and the ratio of flower abscission were compared between the two flower types. Significant differences were detected only in female fertility between the two flower types. At the flowering stage, 6.8% of flowers were terminal flowers, whereas at the young pod stage, all young fruits were obtained from lateral flowers. At the final stage of blooming, based on the generalized linear model analysis, the ratio of surviving terminal flowers was lower than that of the lateral flowers in a capitulum. These results suggest that the terminal flowers of A. julibrissin had female sterility or, at least, female fertility was lower than in lateral flowers. Therefore, it is necessary to reexamine some previous studies that assumed A. julibrissin to be andromonoecious with hermaphroditic terminal flowers and male lateral flowers. Further comparisons of the quality of ovules and polyads are necessary to clarify whether there is a division of labor between the terminal and lateral flowers in A. julibrissin. [ABSTRACT FROM AUTHOR]

Flower and fruit abscission is a highly programmed physiological process, which is closely related to the yield of horticultural plants. The coordination of many regulatory factors associated with metabolic and signaling pathways plays a key role in the flower and fruit shedding. Hormones, peptides, carbohydrates, polyamines or cell wall modifying proteins regulate flower and fruit shedding. This article reviewed the recent studies of flower and fruit abscission, including the molecular regulation mechanism of abscission zone formation, typical structure and location of abscission zones, and other factors affecting flower and fruit abscission, such as stresses, hormones, peptides, carbohydrates, polyamines and cell wall modifying proteins. Overall, the review summarizes the developmental mechanism and the diversity of abscission zones, and the key factors affecting flower and fruit abscission of horticultural plants, aiming to provide guidance for studying the molecular regulatory mechanism of flower and fruit abscission. [ABSTRACT FROM AUTHOR]

A high pod abscission rate in soybean plants results in a significant decrease in the yield per plant. Under dense planting conditions, dense tolerant soybean cultivars had a relatively low rate of pod abscission, thereby facilitating higher yield. In this experiment, two planting densities were used to analyze the differentially expressed genes and metabolites between the abscised and non-abscised flowers of two soybean cultivars on the basis of transcriptomic and metabolomic techniques. The flower abscission rate of LD32 was significantly lower than that of SND28. Both cultivars were enriched in the photosynthesis, sugar, and starch metabolism; MAPK signaling; and phenylalanine metabolism pathways at different planting densities. However, under dense planting, the trend of differential gene changes in the density-tolerant CV LD32 was opposite to that of the conventional CV SND28. The results of the joint analysis indicated that the co-regulation of cytokinin dehydrogenase 6 (CKX6) and cis-zeatin riboside monophosphate (CZRM) in the zeatin biosynthesis pathway of LD32 under dense planting conditions was the main factor for the relatively low rate of pod abscission under dense planting conditions. [ABSTRACT FROM AUTHOR]

Selecting suitable street trees is critical for avoiding these problems of street trees. Resident experiences should be considered in street tree selection to improve effective management because resident preferences tend to differ from those of street tree managers. This study aimed to explore the criteria for street tree selection by residents and compare the criteria between residents and experts. This study implemented two studies to achieve the study purpose. Study 1 used exploratory factor analysis to explore the factors and items of street tree selection from residents. This study assessed the items of initial factors and street tree selection through 124 valid questionnaires. The results indicated that the seven common factors of street tree selection included public health and safety, maintenance and management, fallen flowers and fruits, visual landscapes, functional requirements, growth characteristics, and flower characteristics. According to the factors and items of Study 1, Study 2 evaluated and compared criteria weights of street tree selection between residents and experts through the analytical hierarchy process. Ten student samples from each expert and public group were surveyed. Public health and safety, maintenance and management, and fallen fruits accounted for 68 and 71% of the total weights in the expert and public groups, respectively. The public group had significant concerns about fallen fruits, pods, and seeds, which should be carefully considered when selecting street trees. Designers and managers of landscape and planting engineering should consider weight scores to select the appropriate street tree species. [ABSTRACT FROM AUTHOR]

• Cut lilies respond to ethylene in a tissue-specific manner. • Ethylene accelerates only flower senescence in cold-stored flowers. • Cold stress changes ethylene perception through changes at receptor level. • 1-MCP is effective in delaying flower senescence but not leaf senescence. Fresh cut lily flowers often have a long postharvest life and produce undetectable levels of ethylene. This changes after cold storage, when lilies produce a higher amount of ethylene with a very early leaf and then flower senescence. Such changes to postharvest physiology are likely ethylene-dependant, either due to a higher level of ethylene production or a change in ethylene sensitivity as a result of alteration in the expression of genes involved in the biosynthesis, perception and signalling of ethylene. Therefore, we investigated the transcriptional regulation of ethylene biosynthesis, perception, and signalling pathways in response to cold storage in the cut lily cultivar 'Marlon'. Cut lily stems were treated as follows: 1) control (no treatments), 2) 1-Methylcyclopropene (1-MCP; an ethylene action inhibitor) (10 nL L −1), 3) ethylene (10 μL L −1), and 4) 1-MCP (10 nL L −1) + ethylene (10 μL L −1) for 12 h, thereafter, half of each treated group were cold stored at 5 °C in 12 h light/dark condition for 7 days. We assessed quality characteristics, ethylene production, and the expression of its biosynthesis, perception, and signalling genes. Ethylene and 1-MCP treatments had no effects on non-cold-stored plants. Cold storage led to much earlier leaf yellowing (from 8 to 4 days), and flowers senesced and abscised 3 days earlier. In cold-stored plants, flower senescence and abscission were hastened by ethylene and delayed by 1-MCP. These findings indicate that ethylene does influence flower senescence following cold storage but leaf senescence is under the control of other factors. Our results suggest that treatments that focus on ethylene blockers to prolong postharvest life in lilies will be effective for flowers but not leaves. [ABSTRACT FROM AUTHOR]

Seasonal greening is a crucial survival strategy for albino tea cultivars, during which dysfunctional chloroplasts recover and chlorophyll biosynthesis increases in albino leaves. However, the regulatory mechanisms of seasonal greening in albino tea plants remain unclear. Here, we report that CsRVE1, a nuclear-located Myb-like transcription factor, can positively modulate the seasonal greening of albino Camellia sinensis cv. Huangkui leaves by activating the expression of genes involved in light harvesting and chlorophyll biosynthesis. The transcriptional expression of CsRVE1 increased during seasonal greening and was tightly correlated with increases in the expression of genes involved in light harvesting (CsLhcb) and chlorophyll biosynthesis (CsCHLH , CsHEMA1 and CsCAO). In vivo and in vitro molecular analyses showed that CsRVE1 can directly bind to the promoters of CsLhcb , CsCHLH and CsPORA , eventually leading to chlorophyll accumulation in tea leaves. Furthermore, transient suppression of CsRVE1 in tea leaves led to a decrease in target gene expression. In contrast, the overexpression of CsRVE1 in Arabidopsis led to chlorophyll increases and the activation of AtLhcb , AtPORA , AtCHLH , etc. These results identify CsRVE1 as an important promoter of seasonal greening that functions by regulating genes involved in chlorophyll biosynthesis in albino tea plants and shed new light on the regulatory mechanisms of leaf phenotypes in plants. [ABSTRACT FROM AUTHOR]

Key message: RbIDL1 and RbIDL4 are up-regulated in an ethylene-responsive manner during rose petal abscission and restored the Arabidopsis ida-2 mutant abscission defect suggesting functional conservation of the IDA pathway in rose. Abscission is an ethylene-regulated developmental process wherein plants shed unwanted organs in a controlled manner. The INFLORESCENCE DEFICIENT IN ABSCISSION family has been identified as a key regulator of abscission in Arabidopsis, encoding peptides that interact with receptor-like kinases to activate abscission. Loss of function ida mutants show abscission deficiency in Arabidopsis. Functional conservation of the IDA pathway in other plant abscission processes is a matter of interest given the discovery of these genes in several plants. We have identified four members of the INFLORESCENCE DEFICIENT IN ABSCISSION-LIKE family from the ethylene-sensitive, early-abscising fragrant rose, Rosa bourboniana. All four are conserved in sequence and possess well-defined PIP, mIDa and EPIP motifs. Three of these, RbIDL1, RbIDL2 and RbIDL4 show a three–fourfold increase in transcript levels in petal abscission zones (AZ) during ethylene-induced petal abscission as well as natural abscission. The genes are also expressed in other floral tissues but respond differently to ethylene in these tissues. RbIDL1 and RbIDL4, the more prominently expressed IDL genes in rose, can complement the abscission defect of the Arabidopsis ida-2 mutant; while, promoters of both genes can drive AZ-specific expression in an ethylene-responsive manner even in Arabidopsis silique AZs indicating recognition of AZ-specific and ethylene-responsive cis elements in their promoters by the abscission machinery of rose as well as Arabidopsis. [ABSTRACT FROM AUTHOR]

Cold stress usually causes the abscission of floral organs and a decline in fruit setting rate, seriously reducing tomato yield. Auxin is one of the key hormones that affects the abscission of plant floral organs; the YUCCA (YUC) family is a key gene in the auxin biosynthesis pathway, but there are few research reports on the abscission of tomato flower organs. This experiment found that, under low temperature stress, the expression of auxin synthesis genes increased in stamens but decreased in pistils. Low temperature treatment decreased pollen vigor and pollen germination rate. Low night temperature reduced the tomato fruit setting rate and led to parthenocarpy, and the treatment effect was most obvious in the early stage of tomato pollen development. The abscission rate of tomato pTRV-Slfzy3 and pTRV-Slfzy5 silenced plants was higher than that of the control, which is the key auxin synthesis gene affecting the abscission rate. The expression of Solyc07g043580 was down-regulated after low night temperature treatment. Solyc07g043580 encodes the bHLH-type transcription factor SlPIF4. It has been reported that PIF4 regulates the expression of auxin synthesis and synthesis genes, and is a key protein in the interaction between low temperature stress and light in regulating plant development. [ABSTRACT FROM AUTHOR]

Phytohormones play an important role in regulating the plant behavior to drought. In previous studies, NIBER® pepper rootstock showed tolerance to drought in terms of production and fruit quality compared to ungrafted plants. In this study, our hypothesis was that short-term exposure to water stress in young, grafted pepper plants would shed light on tolerance to drought in terms of modulation of the hormonal balance. To validate this hypothesis, fresh weight, water use efficiency (WUE) and the main hormone classes were analyzed in self-grafted pepper plants (variety onto variety, V/V) and variety grafted onto NIBER® (V/N) at 4, 24, and 48h after severe water stress was induced by PEG addition. After 48h, WUE in V/N was higher than in V/V, due to major stomata closure to maintain water retention in the leaves. This can be explained by the higher abscisic acid (ABA) levels observed in the leaves of V/N plants. Despite the interaction between ABA and the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), in relation to stomata closure is controversial, we observed an important increase of ACC at the end of the experiment in V/N plants coinciding with an important rise of the WUE and ABA. The maximum concentration of jasmonic acid and salicylic acid after 48h was found in the leaves of V/N, associated with their role in abiotic stress signaling and tolerance. Respect to auxins and cytokinins, the highest concentrations were linked to water stress and NIBER®, but this effect did not occur for gibberellins. These results show that hormone balance was affected by water stress and rootstock genotype, where NIBER® rootstock displayed a better ability to overcome short-term water stress. [ABSTRACT FROM AUTHOR]

The Liangzhu City site, located in the center of the Liangzhu Culture (3300–2300 cal. BC), is characterized by gigantic earthen mounds containing about 10 million m3 of earth, as well as crisscrossed waterways that flow through the mounds. This study presents a geoarchaeological study of a mound structure adjacent to the South Zhongjiagang channel of Liangzhu City. By applying soil micromorphological and associated bulk sedimentological analyses, this study reconstructed the site formation processes and multiple occupations of the mound structure together with related hydrological changes. The results suggest that this site is in a near‐bank activity area formed due to the build‐up of sequential settlement buildings and activity deposits. At least six intact activity surfaces have been recognized based on the presence of intact matting materials and the trampling of fine anthropogenic debris. This study thus reports the first detailed micromorphological study of Neolithic floor sequences in East China. In addition, lipid and isotope analyses of the plant material shed light on how Liangzhu people exploited grass materials, especially bamboo, for both long‐term and short‐term occupation near waterways. This study has demonstrated the potential of micromorphological studies for reconstructing site formation processes and identifying different types of human activities in a landscape that was highly modified by Neolithic people. The findings have far‐reaching implications for archaeological research around the Tai Lake region and investigations of other large earthen mound archaeological sites around the world. [ABSTRACT FROM AUTHOR]

The regulation of abscission has a significant impact on fruit yield and quality. Thus, understanding the mechanisms underlying abscission, particularly identifying key genes, is critical for improving fruit crop breeding and cultivation practices. Here, to explore the key genes involved in litchi fruitlet abscission, the two closest homologs of AGAMOUS-like 15/18 (LcAGL15 and LcAGL18) were identified. During the litchi fruitlet abscission process, LcAGL15 expression was reduced, whereas LcAGL18 expression was increased at the abscission zone. The abscission of floral organs was unaffected by ectopic expression of LcAGL15 in Arabidopsis. Moreover, high expression of LcAGL18 significantly delayed the abscission process of floral organs, particularly the sepals. Overexpression of LcAGL18 in Arabidopsis consistently repressed the expression of abscission-related genes, including HAESA (HAE) and HAESA-LIKE2 (HSL2), and cell wall remodeling genes at the abscission zone. Furthermore, LcAGL18 was localized in the nucleus and acted as a transcriptional inhibitor. Collectively, these results suggest that AGL18 homologs have conserved functions in Arabidopsis and litchi, and that LcAGL18 might function as a key regulator in litchi fruitlet abscission. [ABSTRACT FROM AUTHOR]

Phelipanche aegyptiaca is an obligate holoparasite that causes serious negative effects on crop growth and productivity, effective control of which is difficult due to its unique biological characteristics. In this study, we performed a comparative transcriptome analysis of resistant and susceptible Cucumis melo cultivars (KR1326 and K1237) inoculated with P. aegyptiaca. CmNLR (encodes a TIR-type NLR protein, consistently highly expressed in KR1326 roots) and CmNLRh (homologous gene of CmNLR) were cloned and overexpressed in K1237 roots to verify whether the TIR-type NLR protein can enhance C. melo resistance to P. aegyptiaca. The variations in enzymes related to active oxygen metabolism were further detected in transformed roots. The results showed that (1) some differentially expressed genes (DEGs) were enriched in pathways associated with active oxygen scavenging; (2) several DEGs encoded transcription factors, calcium channel proteins, and receptor-like proteins were upregulated and expressed in KR1326 roots; (3) the complete CmNLR and CmNLRh proteins prevented P. aegyptiaca from connecting to the vascular system of C. melo roots; and (4) stronger active oxygen burst and scavenging capacity were detected in transformed roots. We herein demonstrated that the TIR-type NLR protein confers C. melo resistance to P. aegyptiaca. The results provided clues for finding a new direction for host resistance against parasitic plants and shed new light on the cultivation of resistant varieties to control P. aegyptiaca. [ABSTRACT FROM AUTHOR]

Summary: In many plant species, petal abscission can be considered the final step of petal senescence. Cytokinins (CKs) are powerful suppressors of petal senescence; however, their role in petal abscission is ambiguous.Here, we observed that, in rose (Rosa hybrida), biologically active CK is accumulated during petal abscission and acts as an accelerator of the abscission process. Using a combination of reverse genetics, and molecular and biochemical techniques, we explored the roles of a LESION SIMULATING DISEASE1 (LSD1) family member RhLOL1 interacting with a bHLH transcription factor RhILR3 in CK‐induced petal abscission.Silencing RhLOL1 delays rose petal abscission, while the overexpression of its ortholog SlLOL1 in tomato (Solanum lycopersicum) promotes pedicel abscission, indicating the conserved function of LOL1 in activating plant floral organ abscission. In addition, we identify a bHLH transcription factor, RhILR3, that interacts with RhLOL1. We show that RhILR3 binds to the promoters of the auxin signaling repressor auxin/indole‐3‐acetic acid (Aux/IAA) genes to inhibit their expression; however, the interaction of RhLOL1 with RhILR3 activates the expression of the Aux/IAA genes including RhIAA4‐1. Silencing RhIAA4‐1 delays rose petal abscission.Our results thus reveal a RhLOL1–RhILR3 regulatory module involved in CK‐induced petal abscission via the regulation of the expression of the Aux/IAA genes. [ABSTRACT FROM AUTHOR]

The unwanted detachment of organs such as flowers, leaves, and fruits from the main body of a plant (abscission) has significant effects on agricultural practice. Both timely and precise regulation of organ abscission from a plant is crucial as it influences the agricultural yield. The tomato (Solanum lycopersicum) has become a model system for research on organ abscission. Here, we characterized four tomato natural abscission variants named jointless (j), functionally impaired jointless (fij), functionally impaired jointless like (fij like), and normal joint (NJ), based on their cellular features within the flower abscission zones (AZ). Using eight INFLORESCENCE DEFICIENT IN ABSCISSION (SlIDA) genes and eight HAESA genes (SlHAE) identified in the genome sequence of tomato, we analyzed the pattern of gene expression during flower abscission. The AZ-specific expression for three tomato abscission polygalacturonases (SlTAPGs) in the development of flower AZ, and the progression of abscission validated our natural abscission system. Compared to that of j, fij, and fij like variants, the AZ-specific expression for SlIDA, SlIDL2, SlIDL3, SlIDL4, and SlIDL5 in the NJ largely corelated and increased with the process of abscission. Of eight SlHAE genes examined, the expression for SlHSL6 and SlHSL7 were found to be AZ-specific and increased as abscission progressed in the NJ variant. Unlike the result of gene expression obtained from natural abscission system, an in silico analysis of transcriptional binding sites uncovered that SlIDA genes (SlIDA, SlIDL6, and SlIDL7) are predominantly under the control of environmental stress, while most of the SlHSL genes are affiliated with the broader context in developmental processes and stress responses. Our result presents the potential bimodal transcriptional regulation of the tomato IDA-HAE module associated with flower abscission in tomatoes. [ABSTRACT FROM AUTHOR]

Boron (B) is an essential trace nutrient element for citrus, but excessive B levels are frequently encountered in citrus production, potentially resulting in citrus toxicity. To better understand the tolerance and physiological responses of citrus rootstocks to excess B levels, Trifoliate orange, Ziyangxiangcheng, Carrizo citrange, and Red tangerine were treated with four B concentrations (0.05, 0.2, 0.8, and 3.2 mmol/L). High B concentrations resulted in leaf yellowing and shedding and eventual plant death. Chlorophyll content and photosynthetic capacity declined in response to high B concentrations, and relative leaf cell conductivity rose significantly. Trifoliate orange was the first to exhibit symptoms of B toxicity, with the highest levels of B-associated injury. As B concentrations rose, the height increment ratio declined, as did belowground and aboveground dry fresh weight. Soluble protein content initially rose and then fell, while proline content, SOD activity, and POD activity rose with B concentrations. B levels in these rootstocks also increased significantly, with the greatest increases in the leaves. Principal component analysis and subordinate function results revealed that the relative rank order for the B tolerance of citrus rootstocks was: Red tangerine > Carrizo citrange > Ziyangxiangcheng > Trifoliate orange. [ABSTRACT FROM AUTHOR]

Introduction: Camellia is among the most ornamentally valuable flowers and plants worldwide. Flower abscission typically causes significant financial losses by the horticultural landscape. Previous research has revealed that phytohormones, transcription factors, and other genes involved in floral development regulate the maintenance and mortality of flowers Methods: In this study, for the first time, the transcriptomes and targeted hormone metabolomics of three developmental stages of the receptacles of two distinct camellia strains (CF: abscission strain, CHF: nonabscission strain) were analyzed to determine their roles in regulating blossom abscission in camellia. Results: ABA content was shown to be considerably upregulated throughout all phases of CF development, as were the genes implicated in the ABA production pathway and their downstream counterparts. Highly expressed genes in CF were involved in galactose metabolism, phenylpropanoid biosynthesis, amino and nucleotide sugar metabolism, pentose and glucuronate interconversions, and MAPK. Among others, highly expressed genes in CHF are associated with fructose and mannose metabolism, alphalinolenic acid metabolism, biosynthesis of secondary metabolites, starch and sucrose metabolism, and cutin, suberin, and wax biosynthesis. A vast variety of stress response-related pathways and redox-related activities were also shown to be active in CHF. In contrast, CF dramatically activated pathways associated with lignin production, keratinogenesis, cell wall biogenesis, and ABA response. A comparative transcriptomic study of the CF and CHF pathways revealed that the downstream response pathways of hormones, including CTK, BR, IAA, ethylene, and GA, were very active in CF, indicating a significant amount of signal transduction and transcriptional regulation by CF. In addition, members of the transcription factor family, such as MYB, bHLH, MADS, and WD40, may regulate flower abscission. Discussion: A comparative transcriptome analysis of two distinct strains of camellia receptacles elucidates the molecular processes and regulatory characteristics of flower abscission and provides direction for the targeted improvement and breeding of camellia. [ABSTRACT FROM AUTHOR]

Aphis odinae, a polyphagous aphid, was found infesting cashew trees in Puttur, Karnataka. The damage symptoms caused by these aphids, their seasonality and their natural enemies were recorded in this study. The incidence of aphids was observed from August and April every year. The aphids infest emerging flushes, inflorescences and developing nuts. Severe damage to inflorescence resulted in the drying of flowers and the premature fall of tiny nuts. However, medium-sized cashew nuts usually mature or tolerate the aphid infestation without any damage. The size and germination percentage of aphid infested matured nuts, and healthy nuts indicated not much variation. Under field conditions, four species of coccinellids and three species of syrphids were found predating on different stages of aphids and brought their population under control within a short period. The species of ants associated with aphids were also documented. Considering the incidence and severity of the damage, it is a minor pest of cashew in the study area. [ABSTRACT FROM AUTHOR]

In the Malveae tribe (Malvaceae), the axis supporting the flower has a joint at the upper third. This axis can be considered as an articulated pedicel, peduncle, peduncle-pedicel, or anthopodium. Such disparity in terminology reveals a duality in interpretation since this structure is classified as part of the inflorescence or part of the flower. In an effort to reach a consensus, this study aims to evaluate axes supporting the flowers of species from the Malveae tribe through ontogenetic, morphological, and histochemical analyses, using light microscopy and scanning electron microscopy. Ontogenetic analyses indicated that the axis supporting the flower is an articulated pedicel, which is divided into proximal and distal parts owing to the presence of the constriction (joint). Simultaneously, the articulated pedicel arises from the floral meristem, along with the establishment of the calyx and androecium. As development progresses, we observed frequent abscissions of the floral bud, along with the distal portion of the pedicel, at the joint. After this, the remaining proximal portion of the pedicel becomes secretory, as an extrafloral nectary, often foraged by ants of the genus Wasmannia. Thus, this ontogenetic analysis of the articulated pedicel helps in understanding its functionality and morphological variability, highlighting the importance of standardized terminology since it would lead to conceptual clarity in different studies. Additionally, this study, for the first time, reveals the presence of extrafloral nectaries on articulated pedicels in Malveae, a previously undocumented feature in Malveae and Malvaceae. [ABSTRACT FROM AUTHOR]

The production of cassava (Manihot esculenta Crantz) is constantly threatened by cassava bacterial blight (CBB), caused by Xanthomonas phaseoli pv. manihotis (Xpm). Zinc finger-homeodomain (ZF-HD) belongs to a family of homozygous heterotypic cassette genes widely implicated in various developmental and physiological processes in plants. Despite their importance, a comprehensive analysis of ZF-HD genes, particularly those involved in disease resistance, has not been performed for cassava. In the present study, we utilized bioinformatics methods to identify 21 ZF-HD genes distributed across 11 chromosomes of cassava genome, with the majority exhibiting gene structure without introns. Phylogenetic analysis categorized these genes into two major groups (MIF and ZHD) with five subgroups. We observed fourteen pairs of duplicated genes, suggesting that segmental duplication has likely facilitated the expansion of the cassava ZF-HD gene family. Comparative orthologous analyses between cassava and other plant species shed light on the evolutionary trajectory of this gene family. Promoter analyses revealed multiple hormone- and stress-related elements, indicative of a functional role in stress responses. Expression profiling through RNA-seq and quantitative real-time PCR (qRT-PCR) demonstrated that certain cassava ZF-HD genes are up-regulated in response to Xpm infection, suggesting their involvement in defense mechanisms. Notably, MeZHD7 gene was identified via virus induced gene silencing (VIGS) as potentially crucial in conferring resistance against CBB. Results from subcellular localization experiments indicated that MeZHD7 was localized in the nucleus. The Luciferase reporter assay demonstrated an interaction between MeZHD7 and MeMIF5. These findings may lay the foundation for further cloning and functional analyses of cassava ZF-HD genes, particularly those associated with pathogen resistance. [ABSTRACT FROM AUTHOR]

Premature abscission of flowers and fruits triggered by low light stress can severely reduce crop yields. However, the underlying molecular mechanism of this organ abscission is not fully understood. Here, we show that a gene (SlCLV3) encoding CLAVATA3 (CLV3), a peptide hormone that regulates stem cell fate in meristems, is highly expressed in the pedicel abscission zone (AZ) in response to low light in tomato (Solanum lycopersicum). SlCLV3 knockdown and knockout lines exhibit delayed low light-induced flower drop. The receptor kinases SlCLV1 and BARELY ANY MERISTEM1 function in the SlCLV3 peptide-induced low light response in the AZ to decrease expression of the transcription factor gene WUSCHEL (SlWUS). DNA affinity purification sequencing identified the transcription factor genes KNOX-LIKE HOMEDOMAIN PROTEIN1 (SlKD1) and FRUITFULL2 (SlFUL2) as SlWUS target genes. Our data reveal that low light reduces SlWUS expression, resulting in higher SlKD1 and SlFUL2 expression in the AZ, thereby perturbing the auxin response gradient and causing increased ethylene production, eventually leading to the initiation of abscission. These results demonstrate that the SlCLV3- SlWUS signaling pathway plays a central role in low light-induced abscission by affecting auxin and ethylene homeostasis. [ABSTRACT FROM AUTHOR]

Floral organ abscission is a separation process in which sepals, petals, and stamens detach from the plant at abscission zones. Here, we investigated the collective role of three amino-acid-loop-extension (TALE) homeobox genes ARABIDOPSIS THALIANA HOMEOBOX GENE1 (ATH1) , KNAT6 (for KNOTTED LIKE from Arabidopsis thaliana) and KNAT2 , which form a module that patterns boundaries under the regulation of BLADE-ON-PETIOLE 1 and 2 (BOP1/2) co-activators. These TALE homeodomain transcription factors were shown to maintain boundaries in the flower, functioning as a unit to coordinate the growth, patterning, and activity of abscission zones. Together with BOP1 and BOP2, ATH1 and its partners KNAT6 and KNAT2 collectively contribute to the differentiation of lignified and separation layers of the abscission zone. The genetic interactions of BOP1/2 and ATH1 with INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) were also explored. We showed that BOP1/2 co-activators and ATH1 converge with the IDA signalling pathway to promote KNAT6 and KNAT2 expression in the abscission zone and cell separation. ATH1 acts as a central regulator in floral organ abscission as it controls the expression of other TALE genes in abscission zone cells. [ABSTRACT FROM AUTHOR]