Plant Cell Reports最新文献

Key message: This study identifies 11 ZmACP genes in maize, revealing their role in salt stress adaptation, with ZmACP1 overexpression enhancing salt tolerance in Arabidopsis. Soil salinity is an escalating global threat that compromises crop yields. Acyl carrier proteins (ACPs) are essential cofactors of type II fatty acid synthase that determine acyl-chain length and unsaturation, yet their evolutionary diversification and functional relevance to salt stress remain poorly understood in maize (Zea mays L.). In this study, we identified 11 nonredundant ZmACP genes encoding proteins of 105-141 amino acids that are distributed across eight chromosomes. Phylogenomic analysis of 73 ACPs from seven species revealed two clades that reflected monocot-dicot divergence. Duplication analyses revealed one segmental duplication (ZmACP1/ZmACP5), indicating that the family expanded through small-scale events. We detected 33 collinear gene pairs between maize and four monocots, but none between maize and two dicots, further supporting monocot-dicot divergence. All ZmACPs retained the canonical DSL motif and adopted a four-helix bundle fold. Analysis of the cis-acting elements in the ZmACP promoters revealed their potential involvement in hormone and stress responses. Expression profiling of selected ZmACPs under salt stress revealed rapid induction of ZmACP1, peaking at 6-12 h and then declining. Ectopic overexpression of ZmACP1 in Arabidopsis enhanced salt tolerance, increasing shoot dry weight and chlorophyll retention (SPAD) 2.3 and 4.2-fold, respectively, under 300 mM NaCl, indicating a positive role in the salt response, potentially through mechanisms related to lipid metabolism. Taken together, our integrated genomic, evolutionary, and functional data confirm that ZmACP genes participate in salt stress regulation and provide candidate genes and molecular targets for breeding salt-tolerant maize.

Key message: IbMYB genes were systematically identified in sweetpotato, linking their crucial functions in abiotic stress response, with IbMYB150 enhancing salt tolerance in yeast and Arabidopsis. MYB transcription factors play crucial roles in regulating plant responses to various environmental stresses. Sweetpotato is a versatile crop with comprehensive agronomic advantages unmatched by other crops; however, systematic information and functional studies on MYB genes in sweetpotato remain scarce. Herein, employing stringent screening criteria, 339 putative IbMYB genes were identified in sweetpotato genomes, comprising 164 1R-MYB, 166 2R-MYB, 6 3R-MYB, 1 4R-MYB, and 2 5R-MYB. These genes were unevenly distributed across chromosomes, with segment duplications serving as the primary driving force for IbMYB expansion. Conserved motifs and gene structures were characterized within the same subgroups, and synteny detection revealed extensive collinear MYB gene pairs between sweetpotato and other plants, providing insights into IbMYB evolution. Through transcriptome screening and qRT-PCR validation, we identified IbMYB-061/-065/-095/-150/-280L as nuclear-localized transcriptional activators significantly induced by abiotic stress. Heterologous expression in yeast demonstrated that all these selected IbMYBs substantially enhanced salt tolerance. Furthermore, ectopic expression of IbMYB150 in Arabidopsis significantly improved salt tolerance during germination and seedling stages. Collectively, these findings lay the groundwork for elucidating the pivotal roles of IbMYBs in regulating stress tolerance in sweetpotato.

Key message: CaRCC1-16 confers thermotolerance in pepper by interacting with stress-related proteins, enhancing photosynthetic efficiency, regulating stomatal activity, and modulating the expression of stress-responsive genes. Pepper (Capsicum annuum L.) is an economically important crop with high medicinal and biopesticidal properties that faces severe yield losses due to abiotic stresses. The regulator of chromosomal condensation 1 (RCC1) family protein is known to play important roles in plant growth, development, and stress responses. While several RCC1 members have been functionally characterized in Arabidopsis and other species, their role in pepper remains largely unexplored. In this study, we identified 28 CaRCC1 genes in pepper genome, unevenly distributed across 11 chromosomes. Phylogenetic characterization divided these genes into six groups, with members within each group sharing conserved gene structure and protein motif/domain structure. Promoter analysis revealed a high density of cis-acting elements associated with growth, hormone signaling, and stress responses. Furthermore, transcript profiling ABA and various abiotic stresses (heat, cold, drought, and salinity) revealed differential expression patterns, with CaRCC1-16 showing prominent transcription induction. Subcellular localization confirmed that CaRCC1-16 localized in the nucleus. Bimolecular fluorescence complementation analysis shows the interaction of CaRCC1-16 with ATpase, E2 18 and ETIF3 in the cytoplasm. Functional analyses of CaRCC1-16 demonstrate its role as a positive regulator of thermotolerance in pepper. Overexpression of CaRCC1-16 in pepper enhances heat tolerance by improving photosynthetic efficiency, regulating stomatal activity, reducing lipid peroxidation, and mitigating reactive oxygen species accumulation. In contrast, silencing of CaRCC1-16 results in increased heat sensitivity, overall, these findings elucidate the evolutionary history of the CaRCC1 family and, insights into the molecular mechanisms underlying pepper response to high temperature stress and, more significantly, define a previously unknown and important role for CaRCC1-16 in mediating the heat stress response through a novel protein interaction network. Contributing to our understanding of the biological functions of the RCC1 gene family in plant abiotic stress interaction, provides a foundation for crop improvement strategies.

Avena fatua L. is a major grass weed infesting wheat fields worldwide, with the ACCase-inhibiting herbicide fenoxaprop-P-ethyl serving as the primary chemical control agent. However, prolonged and widespread use has resulted in the evolution of resistance in A. fatua, posing a serious threat to effective weed management in wheat production. This study investigates the resistance level and elucidates the underlying mechanisms in a fenoxaprop-P-ethyl-resistant A. fatua population (HZXH-R) collected from China. Whole-plant bioassays demonstrated that the HZXH-R population exhibited a 21.3-fold resistance to fenoxaprop-P-ethyl compared with sensitive population. Sequencing of the ACCase gene detected no known target-site mutations, thereby excluding target-site mutation-mediated resistance. Treatment with cytochrome P450 inhibitors (piperonyl butyl ether [PBO], malathion, and 1-aminobenzotriazole [ABT]) significantly reduced resistance in HZXH-R, implicating P450 monooxygenases in resistance regulation. Transcriptome sequencing identified six genes that were significantly upregulated and two that were downregulated. RT-qPCR validation confirmed that the P450 gene CYP710A8B showed the highest relative expression in the resistant population. This study demonstrates that the A. fatua population HZXH-R exhibits high-level resistance to fenoxaprop-P-ethyl, with the upregulation of CYP710A8B identified as a potential factor in resistance development. These findings provide a foundation for elucidating the evolutionary mechanisms underlying resistance to ACCase-inhibiting herbicides and for guiding the development of more effective, science-based weed management strategies.

Key message: Embryogenic efficiency in wheat microspores is driven by epigenetic regulation, homoeolog expression bias, and genotype-specific genomic variation, with coordinated remodeling of metabolic pathways and cell-wall dynamics establishing a favourable cellular environment. Microspore embryogenesis is a process in which immature male gametophytes are induced to form embryo-like structures that can regenerate into doubled haploid (DH) plants following chromosome doubling. By producing complete homozygosity in a single generation, DH technology accelerates cultivar development and is particularly valuable for breeding resilient crops. However, bread wheat remains largely recalcitrant to microspore embryogenesis, with strong genotype dependence limiting its broad application in breeding programs. Here, we performed a comparative transcriptomic time-course in two spring wheat cultivars with contrasting embryogenic responses: Nanda (highly responsive) and Sadash (recalcitrant). Dynamic gene expression reprogramming was observed during embryogenesis, with Nanda exhibiting enrichment of biological processes associated with epigenetic regulation, including nucleosome assembly, chromatin remodeling, and chromatin organization. In addition, genes related to stress perception, hormonal signaling, cytoskeletal and cell wall dynamics, and metabolic pathways showed coordinated expression changes, collectively characterizing the transcriptional landscape associated with successful microspore embryogenesis. Differentially expressed gene (DEG) hotspots identified structural variation underlying the divergent responses between genotypes. Machine learning highlighted potential biomarkers, notably a histone deacetylase gene TRAESCS1D02G454400 located within a DEG-enriched region. Subgenome-specific analysis revealed pronounced suppression of B-subgenome homoeologs in Sadash, 65% of which overlapped with DEGs from the genotype comparison. These findings highlight the role of epigenetic regulation, homoeolog expression bias, and genotype-specific genomic variation in determining embryogenic efficiency. Importantly, these conclusions are based on transcriptomic associations and require functional validation, while providing candidate molecular targets and biomarkers to overcome recalcitrance and enhance the utility of microspore embryogenesis in wheat DH breeding.

Key message: PpCML14 confers drought and salinity tolerance by interacting with PpGMP1 for improved AsA biosynthesis and upregulating antioxidant enzyme activities, proline accumulation, and stress-responsive genes. Calcium is a universal second messenger in plant cells, regulating plant growth, development, and responses to environmental stresses. Calmodulin-like proteins (CMLs) are one of the Ca²⁺ sensors or Ca²⁺-binding proteins. However, the functions of lots of members in CML family remain largely unknown. A PpCML14 from the native Kentucky bluegrass (Poa pratensis L.) was examined to regulate drought and salinity tolerance in the present study. PpCML14 is highly expressed in roots, and its overexpression in rice resulted in increased drought and salinity tolerance, with promoted activities of antioxidant enzymes, including superoxide dismutase, catalase, and ascorbate peroxidase, proline accumulation, and expressions of ABA-dependent and ABA-independent stress-responsive genes. Additionally, PpGMP1 (GDP-D-mannose pyrophosphorylase 1), a key enzyme for ascorbic acid (AsA) biosynthesis, was identified as interacting with PpCML14 based on screening of cDNA library and further confirmation using the methods of yeast-two-hybridization, firefly luciferase complementation imaging (LCI), pull-down, and co-immunoprecipitation (Co-IP). Overexpression of PpGMP1 in rice led to increased drought and salinity tolerance. AsA levels and AsA redox were higher, but reactive oxygen species (ROS) accumulation was lower in both PpGMP1- and PpCML14-overexpressing rice lines under drought and salinity conditions compared with wild-type plants. The results indicated that AsA biosynthesis is regulated by the PpCML14-PpGMP1 module. AsA is an important antioxidant for scavenging ROS. It is suggested that PpCML14 confers drought and salinity tolerance through upregulating antioxidant enzyme activities, proline accumulation, and stress--responsive genes, and by activating PpGMP1 to improve AsA biosynthesis.

Key message: Transcriptome identification and functional characterization of an ABA-induced R2R3-MYB transcription factor involved in flower petal senescence and abiotic stress responses in Tulipa gesneriana. Tulips (Tulipa gesneriana L.) are cultivated worldwide and hold significant importance in the international markets of ornamental flowers. As a cut flower, petal senescence determines the flower longevity, which seriously affects the ornamental and economic value of tulips. Therefore, revealing the regulation mechanism of petal senescence is of great significance for flower lifespan improvement and cut flowers preservation. Here, we identified 40 MYB genes from transcriptome analysis during the process of flower opening and senescence in tulip. Among them, an ABA-induced R2R3-MYB TgMYB44 is found to be significantly downregulated in senescent petals. Overexpression of TgMYB44 altered the sensitivity to ABA, salt, and osmotic stress, as well as enhanced ABA accumulation and ABA-induced leaf senescence in Arabidopsis. Besides, silencing TgMYB44 in tulip delayed petal senescence by modulating ABA biosynthesis. Taken together, this study proposed that TgMYB44 functions as a positive regulator for petal senescence by enhancing ABA biosynthesis in tulips. These findings advance our understanding of the ABA-induced petal senescence in tulip, and also provide new strategies for biotechnological manipulation of flower longevity and postharvest preservation for tulip cut flowers.

Key message: The evolutionary conserved TOR kinase positively controls growth and development of the moss Physcomitrella, development and function of its chloroplasts, its protein synthesis, and cell-cycle progression. Target of Rapamycin (TOR) is a conserved protein kinase and an important signalling hub in eukaryotes. The moss Physcomitrella (Physcomitrium patens) is a model organism for plant physiology, development, and evolution. However, little is known about TOR signalling in non-vascular plants, including Physcomitrella. Here, we report the effects of inhibiting TOR signalling in Physcomitrella. We identified and characterised Physcomitrella 12-kDa FK506-binding protein (FKBP12), which binds TOR in the presence of rapamycin. Whereas the growth of wild-type protonema is unaffected by rapamycin, overexpressing endogenous FKBP12 rendered the plant susceptible to the inhibitor in a dose-dependent manner. Likewise, protonema growth was inhibited when the TOR-specific inhibitor AZD8055 was present in the culture. We show that rapamycin and AZD8055 have pleiotropic effects, as they delay cell-cycle progression and development, induce chlorosis, inhibit photosynthesis, and alter total protein content. Additionally, we identified and characterised PpTOR, PpLST8, and PpRAPTOR, key components of TOR complex 1 (TORC1), whereas RICTOR and mSIN1 of TORC2 are not encoded by the P. patens genome. We found that PpLST8 substitutes its homolog in yeast to allow cell growth. Physcomitrella mutants were generated with a conditional downregulation of PpTOR, PpLST8, and PpRAPTOR, respectively. They were impaired in growth. Finally, we show TOR-dependent phosphorylation of a well-known TOR phospho-target, the ribosomal protein RPS6, via LC-MS/MS. Collectively, our results show that Physcomitrella growth and development is positively controlled by a conserved TOR kinase. We suggest to further dissect TOR signalling in Physcomitrella in order to elucidate signalling integration via TORC1 in plants.

Protein transport is a tightly regulated and complex cellular process fundamental to growth and development. A critical aspect of this process is the accurate and timely translocation of transcription factors and other components of the transcriptional machinery into the nucleus, which is indispensable for the regulation of gene expression. Calmodulin (CaM), a conserved calcium-sensing protein, binds 4 calcium ions and, upon activation, triggers a cascade of signaling events that fine-tune transcriptional outcomes. Notably, CaM exerts a dual regulatory role-facilitating or inhibiting the nuclear import of proteins depending on the cellular context. This review provides a detailed account of the structure and function of CaM, elucidates the molecular basis of its interactions with nuclear transport components, and presents case studies that substantiate its role as a modulator of nuclear protein trafficking across diverse organisms, including recent findings in plants. In addition, we have summarized the potential future applications and implications of CaM-mediated nuclear transport. This finding paves the way for further exploration of how calcium-signaling and CaM-mediated protein transport shape plant development and stress responses. Beyond elucidating the complex regulation of protein localization in plant cells, this insight may also offer new strategies for enhancing plant growth, development, and resilience under stress conditions.

Key message: Embryo abortion occurred at 20 DAP of HFS × RM, with trans-Zeatin-riboside and brassinolide playing key roles during embryo abortion. Rhododendron is a world-famous flower with high ornamental and economic value. However, hybridization between the Rhododendron subgenus Tsutsusi and subgenus Pentanthera is often hindered by reproductive barriers, which restrict breeding of new cultivars. To determine the reproductive barriers between these two subgenera, artificial crosses were conducted using three cultivars in subgenus Tsutsusi (R. × 'Tiehong' (TH), R. × 'Hongfushi' (HFS) and R. × 'Hongyue' (HY), as the maternal parents), and the wild species R. molle (RM) in subgenus Pentanthera as the paternal parent. The results showed that the pollen tube stopped growing at 1/3 of the style of HY at 72 HAP, indicating a pre-fertilization barrier in HY × RM. The seeds of TH × RM were obtained at 230 DAP, indicating no reproductive barriers. In contrast, HFS × RM embryos developed only globular embryos by 10 DAP and aborted by 20 DAP, indicating a post-fertilization barrier. Hormone-targeted metabolomics determined 21 kinds of plant hormones in the ovaries of TH × RM and HFS × RM. Among them, the contents of trans-Zeatin-riboside (tZr) in TH × RM remained stable from 10 to 20 DAPs; however, in HFS × RM, it decreased significantly by 65% during this stage. Furthermore, Brassinolide (BR) was only detected in the ovaries of HFS × RM at 20 DAP. The results indicated that tZr and BR are likely to be the important hormones responsible for the embryo's abortion, which can aid in breeding of distant hybridization in Rhododendron by adopting suitable strategies to overcome the barriers.