Explore the vast range of titles available.

Drought stress is an important environmental factor limiting plant productivity. In this study, we screened drought-resistant transgenic plants from 65 promoter-pyrabactin resistance 1-like (PYL) abscisic acid (ABA) receptor gene combinations and discovered that pRD29A::PYL9 transgenic lines showed dramatically increased drought resistance and drought-induced leaf senescence in both Arabidopsis and rice. Previous studies suggested that ABA promotes senescence by causing ethylene production. However, we found that ABA promotes leaf senescence in an ethylene-independent manner by activating sucrose nonfermenting 1-related protein kinase 2s (SnRK2s), which subsequently phosphorylate ABA-responsive element-binding factors (ABFs) and Related to ABA-Insensitive 3/VP1 (RAV1) transcription factors. The phosphorylated ABFs and RAV1 up-regulate the expression of senescence-associated genes, partly by up-regulating the expression of Oresara 1. The pyl9 and ABA-insensitive 1-1 single mutants, pyl8-1pyl9 doublemutant, and snrk2.2/3/6 triple mutant showed reduced ABA-induced leaf senescence relative to the WT, whereas pRD29A::PYL9 transgenic plants showed enhanced ABA-induced leaf senescence. We found that leaf senescence may benefit drought resistance by helping to generate an osmotic potential gradient, which is increased in pRD29A::PYL9 transgenic plants and causes water to preferentially flow to developing tissues. Our results uncover the molecular mechanism of ABA-induced leaf senescence and suggest an important role of PYL9 and leaf senescence in promoting resistance to extreme drought stress.

Background: Small heat shock proteins (sHsps), particularly Hsp20 family members, are pivotal for plant thermotolerance and abiotic stress adaptation. However, their evolutionary dynamics and functional roles in Lycium barbarum (goji berry), a commercially significant stress-tolerant crop, remain uncharacterized. This study aims to comprehensively identify LbHsp20 genes, delineate their evolutionary patterns, and decipher their regulatory mechanisms under heat stress to accelerate molecular breeding of resilient cultivars. Methods: Forty-three LbHsp20 genes were identified from the goji genome using HMMER and BLASTP. Phylogenetic relationships were reconstructed via MEGA-X (maximum likelihood, 1000 bootstraps), while conserved motifs and domains were annotated using MEME Suite and InterProScan. Promoter cis-elements were predicted via PlantCARE. Heat-responsive expression profiles of candidate genes were validated by qRT-PCR in two contrasting lines (N7 and 1402) under 42 °C treatment. Results: The LbHsp20 family clustered into 14 subfamilies, predominantly cytoplasmic (subfamilies I–VII). Chromosomal mapping revealed a tandem duplication hotspot on Chr4 (12 genes) and absence on Chr9, suggesting lineage-specific gene loss. All proteins retained the conserved α-crystallin domain (ACD), with 19 members harboring the ScHsp26-like ACD variant. Promoters were enriched in stress-responsive elements (HSE, ABRE, MYC). Heat stress induced significant upregulation (>15-fold in LbHsp17.6A and LbHsp18.3) in N7, whereas 1402 showed weaker induction (<5-fold). Subfamily specific divergence was observed, with cytoplasmic subfamily I genes exhibiting the strongest heat responsiveness. Conclusions: This study unveils the evolutionary conservation and functional diversification of LbHsp20 genes in L. barbarum. The tandem duplication-driven expansion on Chr4 and subfamily specific expression patterns underpin their roles in thermotolerance. These findings establish a foundation for engineering climate-resilient goji varieties.

Background Anthocyanins, which are colored pigments, have long been used as food and pharmaceutical ingredients due to their potential health benefits, but the intermediate signals through which environmental or developmental cues regulate anthocyanin biosynthesis remains poorly understood. Fleshy fruits have become a good system for studying the regulation of anthocyanin biosynthesis, and exploring the mechanism underlying pigment metabolism is valuable for controlling fruit ripening. Results The present study revealed that ABA accumulated during Lycium fruit ripening, and this accumulation was positively correlated with the anthocyanin contents and the LbNCED1 transcript levels. The application of exogenous ABA and of the ABA biosynthesis inhibitor fluridon increased and decreased the content of anthocyanins in Lycium fruit, respectively. This is the first report to show that ABA promotes the accumulation of anthocyanins in Lycium fruits. The variations in the anthocyanin content were consistent with the variations in the expression of the genes encoding the MYB-bHLH-WD40 transcription factor complex or anthocyanin biosynthesis-related enzymes. Virus-induced LbNCED1 gene silencing significantly slowed fruit coloration and decreased both anthocyanin and ABA accumulation during Lycium fruit ripening. An qRT-PCR analysis showed that LbNCED1 gene silencing clearly reduced the transcript levels of both structural and regulatory genes in the flavonoid biosynthetic pathway. Conclusions Based on the results, a model of ABA-mediated development-dependent anthocyanin biosynthesis and fruit coloration during Lycium fruit maturation was proposed. In this model, the developmental cues transcriptionally activates LbNCED1 and thus enhances accumulation of the phytohormone ABA, and the accumulated ABA stimulates transcription of the MYB-bHLH-WD40 transcription factor complex to upregulate the expression of structural genes in the flavonoid biosynthetic pathway and thereby promoting anthocyanin production and fruit coloration. Our results provide a valuable strategy that could be used in practice to regulate the ripening and quality of fresh fruit in medicinal and edible plants by modifying the phytohormone ABA.

Background: Anthocyanins and proanthocyanidins (PAs), as flavonoid compounds with potent antioxidant activity, exhibit significant health-promoting and medicinal properties. Black wolfberry (Lycium ruthenicum Murr.) is renowned for its exceptional anthocyanin content; however, the regulatory mechanisms of anthocyanin biosynthesis remain poorly understood, limiting its biotechnological potential. This study aimed to elucidate the transcriptional regulatory function of LrMYB30 in anthocyanin biosynthesis in black wolfberry. Methods: The regulatory function of LrMYB30 was investigated using virus-induced gene silencing (VIGS), yeast one-hybrid assays, and dual-luciferase reporter assays in black wolfberry. Results: VIGS demonstrated that silencing LrMYB30 promoted anthocyanin accumulation while reducing PA content, establishing that the LrMYB30 transcription factor as a negative regulator of anthocyanin synthesis. Yeast one-hybrid and dual-luciferase reporter assays confirmed that LrMYB30 directly binds to and activates the promoter of LrANR, a key structural gene in PA biosynthesis. In contrast, LrMYB30 neither binds to nor suppresses the promoters of the critical anthocyanin biosynthesis genes LrUF3GT and LrDFR. Conclusions: Thus, LrMYB30 redirects the flavonoid metabolic flux from anthocyanin to PA synthesis through transcriptional activation of LrANR during later fruit development, reducing anthocyanin accumulation and delaying coloration. These findings reveal a novel regulatory mechanism in black wolfberry pigmentation and maturation, providing genetic targets for molecular breeding of high-anthocyanin cultivars.

Lycium ruthenicum is a typical desert halophyte with strong stress resistance and high medicinal value in the Tarim Basin. Root endophytic microbes play critical roles in host adaptation, nutrient cycling, and secondary metabolite accumulation. To clarify the diversity patterns of root endophytic bacteria and fungi and their relationships with environmental factors and fruit quality, high-throughput sequencing was used to analyze microbial community characteristics of Lycium ruthenicum collected from different habitats in the Tarim Basin. The results showed that rarefaction curves of alpha diversity indices (Chao1, Shannon, Pielou_e) tended to be saturated, indicating sufficient sequencing depth. Principal coordinate analysis (PCoA) revealed significant habitat-driven differentiation in both bacterial and fungal community structures. Community composition analysis showed that the relative abundance of dominant taxa at the phylum and genus levels differed significantly among sampling sites. Co-occurrence network analysis indicated that bacterial and fungal networks exhibited high modularity and were dominated by positive synergistic interactions, with Pseudomonas, Bacillus, Sphingomonas, Alternaria, and Fusarium as key hub genera. Moreover, root endophytic communities were significantly correlated with climatic variables, soil physicochemical properties, and fruit quality traits, including anthocyanin (AC), proanthocyanidin (PA), total flavonoids (TF), and total polyphenols (TP). Several keystone microbial genera were closely associated with the accumulation of functional metabolites in fruits. This study reveals the biogeographic distribution and co-occurrence characteristics of root endophytes in Lycium ruthenicum and provides a theoretical basis for understanding microbe–host–environment interactions and the quality improvement of desert medicinal plants.

The C‐REPEAT‐BINDING FACTOR (CBF) pathway has important roles in plant responses to cold stress. How the CBF genes themselves are activated after cold acclimation remains poorly understood. In this study, we characterized cold tolerance of null mutant of RNA‐DIRECTED DNA METHYLATION 4 (RDM4), which encodes a protein that associates with RNA polymerases Pol V and Pol II, and is required for RNA‐directed DNA methylation (RdDM) in Arabidopsis. The results showed that dysfunction of RDM4 reduced cold tolerance, as evidenced by decreased survival and increased electrolyte leakage. Mutation of RDM4 resulted in extensive transcriptomic reprogramming. CBFs and CBF regulon genes were down‐regulated in rdm4 but not nrpe1 (the largest subunit of PolV) mutants, suggesting that the role of RDM4 in cold stress responses is independent of the RdDM pathway. Overexpression of RDM4 constitutively increased the expression of CBFs and regulon genes and decreased cold‐induced membrane injury. A great proportion of genes affected by rdm4 overlapped with those affected by CBFs. Chromatin immunoprecipitation results suggested that RDM4 is important for Pol II occupancy at the promoters of CBF2 and CBF3. We present evidence of a considerable role for RDM4 in regulating gene expression at low temperature, including the CBF pathway in Arabidopsis.

Anthocyanin-derived fleshy fruit pigmentation has become an excellent system for studying the regulatory network underlying fruit ripening and quality. The transcriptional control of anthocyanin biosynthesis by MYB–bHLH–WDR complexes has been well established, but the intermediate signals through which the environmental or developmental cues regulate these transcription factors remain poorly understood. Here we found that nitric oxide (NO) production during Lycium fruit ripening decreased progressively presenting a negative relationship with anthocyanins. After cloning of the nitric reductase ( NR ) gene from Lycium barbarum ( LbNR ) plants, we demonstrated that LbNR -derived NO partially inhibited anthocyanin biosynthesis but enhanced proanthocyanidin (PA) accumulation, and delayed fruit coloration. Application of the NO donor, sodium nitroprusside (SNP), produced a similar effect. The endogenous or exogenous NO downregulated the transcripts both of the regulatory genes and the structural genes that related to anthocyanin biosynthesis, while upregulated both of those genes that related to PA biosynthesis. Given there is a significant negative relationship between the levels of anthocyanins and PAs during Lycium fruit ripening, NO not only inhibited anthocyanin de novo biosynthesis but redirected the flavonoid biosynthetic pathway from anthocyanins to PA production. Two types of LrMYB transcription factors of opposite nature, namely anthocyanin-specific and PA-specific, which belong to the R2R3-MYB subfamily and 1R-MYB subfamily, respectively, were identified from L. ruthenicum fruits. It was further found that NO acts by antagonizing the ABA signaling, a phytohormone we have previously shown playing a positive role in Lycium fruit coloration. Our results provided particularly novel information about NO–ABA–anthocyanin interplay during Lycium fruit development and ripening, which may fill a gap between the developmental cues and the transcriptional regulation of anthocyanin biosynthesis.

The characterization of the PYL/RCAR ABA receptors in a great deal of plant species has dramatically advanced the study of ABA functions involved in key physiological processes. However, the genes in this family are still unclear in Lycium (Goji) plants, one of the well–known economically, medicinally, and ecologically valuable fruit crops. In the present work, 12 homologs of Arabidopsis PYL/RCAR ABA receptors were first identified and characterized from Lycium (L.) barbarum (LbPYLs). The quantitative real–time PCR (qRT–PCR) analysis showed that these genes had clear tissue–specific expression patterns, and most of them were transcribed in the root with the largest amount. Among the three subfamilies, while the Group I and Group III members were down–regulated by extraneous ABA, the Group II members were up–regulated. At 42 °C, most transcripts showed a rapid and violent up–regulation response to higher temperature, especially members of Group II. One of the genes in the Group II members, LbPYL10, was further functionally validated by virus–induced gene silencing (VIGS) technology. LbPYL10 positively regulates heat stress tolerance in L. barbarum by alleviating chlorophyll degradation, thus maintaining chlorophyll stability. Integrating the endogenous ABA level increase following heat stress, it may be concluded that LbPYL–mediated ABA signaling plays a vital role in the thermotolerance of L. barbarum plants. Our results highlight the strong potential of LbPYL genes in breeding genetically modified L. barbarum crops that acclimate to climate change.

Following publication of the original article [1], a reader spotted that the article appears to have some misplaced/duplicated figures. In particular, Fig. 5a and Fig. 6a appear to be identical, and do not match what is written in the text. The authors apologized for this oversight and supplied the original pictures, which are reproduced below.

Background The different actions of abscisic acid (ABA) in the aboveground and belowground parts of plants suggest the existence of a distinct perception mechanism between these organs. Although characterization of the soluble ABA receptors PYR1/PYL/RCAR as well as core signaling components has greatly advanced our understanding of ABA perception, signal transduction, and responses, the environment-dependent organ-specific sensitivity of plants to ABA is less well understood. Results By performing real-time quantitative PCR assays, we comprehensively compared transcriptional differences of core ABA signaling components in response to ABA or osmotic/dehydration stress between maize ( Zea mays L.) roots and leaves. Our results demonstrated up-regulation of the transcript levels of ZmPYL s homologous to dimeric-type Arabidopsis ABA receptors by ABA in maize primary roots, whereas those of ZmPYL s homologous to monomeric-type Arabidopsis ABA receptors were down-regulated. However, this trend was reversed in the leaves of plants treated with ABA via the root medium. Although the mRNA levels of ZmPYL1-3 increased significantly in roots subjected to polyethylene glycol (PEG)-induced osmotic stress, ZmPYL4-11 transcripts were either maintained at a stable level or increased only slightly. In detached leaves subjected to dehydration, the transcripts of ZmPYL1-3 together with ZmPYL5, ZmPYL6, ZmPYL10 and ZmPYL11 were decreased, whereas those of ZmPYL4, ZmPYL7 and ZmPYL8 were significantly increased. Our results also showed that all of the evaluated transcripts of PP2Cs and SnRK2 were quickly up-regulated in roots by ABA or osmotic stress; conversely they were either up-regulated or maintained at a constant level in leaves, depending on the isoforms within each family. Conclusions There is a distinct profile of PYR/PYL/RCAR ABA receptor gene expression between maize roots and leaves, suggesting that monomeric-type ABA receptors are mainly involved in the transmission of ABA signals in roots but that dimeric-type ABA receptors primarily carry out this function in leaves. Given that ZmPYL1 and ZmPYL4 exhibit similar transcript abundance under normal conditions, our findings may represent a novel mechanism for species-specific regulation of PYR/PYL/RCAR ABA receptor gene expression. A difference in the preference for core signaling components in the presence of exogenous ABA versus stress-induced endogenous ABA was observed in both leaves and roots. It appears that core ABA signaling components perform their osmotic/dehydration stress response functions in a stress intensity-, duration-, species-, organ-, and isoform-specific manner, leading to plasticity in response to adverse conditions and, thus, acclimation to life on land. These results deepen our understanding of the diverse biological effects of ABA between plant leaves and roots in response to abiotic stress at the stimulus-perception level.