查看更多>>摘要：The rapid elongation of rice (Oryza sativa) coleoptile is pivotal for the plant plumule to evade hypoxia stress induced by submergence,a condition often arising from overirrigation,ponding,rainstorms,or flooding. While brassinosteroids (BRs) are recognized for their diverse roles in plant growth and develop-ment,their influence on coleoptile elongation under hypoxic conditions remains largely unexplored. In this study,we demonstrate the significant requirement of BRs for coleoptile elongation in deep water. During coleoptile development,Glycogen Synthase Kinase3-Like Kinase2 (GSK2),the central inhibitor of BR signaling in rice,undergoes substantial suppression in deep water but induction in air. In contrast,the dephosphorylated form of BRASSINAZOLE RESISTANT1 (OsBZR1),representing the active form of the key BR signaling transcription factor,is induced in water but suppressed in air. Remarkably,the knockout of GSK3-like kinase genes significantly enhances coleoptile elongation in deep water,strongly indicating a vital contribution of BR response to hypoxia-stimulated coleoptile elongation. Transcriptome analysis uncovers both BR-associated and BR-independent hypoxia responses,implicating substance metabolism,redox reactions,abiotic stress responses,and crosstalk with other hormones in the regulation of BR-induced hypoxia responses. In summary,our findings suggest that rice plumules rapidly elongate coleoptiles through the activation of BR response in deep water,enabling them to escape from submergence-induced hypoxia stress.
查看更多>>摘要：Leaf senescence is an orderly and highly coordinated process,and finely regulated by ethylene and nitro-gen (N),ultimately affecting grain yield and nitrogen-use efficiency (NUE). However,the underlying reg-ulatory mechanisms on the crosstalk between ethylene-and N-regulated leaf senescence remain a mystery in maize. In this study,ethylene biosynthesis gene ZmACS7 overexpressing (OE-ZmACS7) plants were used to study the role of ethylene regulating leaf senescence in response to N deficiency,and they exhibited the premature leaf senescence accompanied by increased ethylene release,decreased chloro-phyll content and Fv/Fm ratio,and accelerated chloroplast degradation. Then,we investigated the dynam-ics changes of transcriptome reprogramming underlying ethylene-accelerated leaf senescence in response to N deficiency. The differentially expressed genes (DEGs) involved in chlorophyll biosynthesis were significantly down-regulated,while DEGs involved in chlorophyll degradation and autophagy pro-cesses were significantly up-regulated,especially in OE-ZmACS7 plants in response to N deficiency. A gene regulatory network (GRN) was predicted during ethylene-accelerated leaf senescence in response to N deficiency. Three transcription factors (TFs) ZmHSF4,ZmbHLH106,and ZmEREB147 were identified as the key regulatory genes,which targeted chlorophyll biosynthesis gene ZmLES22,chlorophyll degrada-tion gene ZmNYC1,and autophagy-related gene ZmATG5,respectively. Furthermore,ethylene signaling key genes might be located upstream of these TFs,generating the signaling cascade networks during ethylene-accelerated leaf senescence in response to N deficiency. Collectively,these findings improve our molecular knowledge of ethylene-accelerated maize leaf senescence in response to N deficiency,which is promising to improve NUE by manipulating the progress of leaf senescence in maize.
查看更多>>摘要：In grain crops such as maize (Zea mays),leaf angle (LA) is a key agronomic trait affecting light interception and thus planting density and yield. Nitrogen (N) affects LA in plants,but we lack a good understanding of how N regulates LA. Here,we report that N deficiency enhanced lignin deposition in the ligular region of maize seedlings. In situ hybridization showed that the bZIP transcription factor gene ZmbZIP27 is mainly expressed in the phloem of maize vascular bundles. Under N-sufficient conditions,transgenic maize over-expressing ZmbZIP27 showed significantly smaller LA compared with wild type (WT). By contrast,zm-bzip27ems mutant showed larger LA under both N-deficient and N-sufficient conditions compared with WT. Overexpression of ZmbZIP27 enhanced lignin deposition in the ligular region of maize in the field. We further demonstrated that ZmbZIP27 could directly bind the promoters of the microRNA genes ZmMIR528a and ZmMIR528b and negatively regulate the expression levels of ZmmiR528. ZmmiR528 knockdown transgenic maize displayed erect architecture in the field by increasing lignin content in the ligular region of maize. Taken together,these results indicate that ZmbZIP27 regulates N-mediated LA size by regulating the expression of ZmmiR528 and modulating lignin deposition in maize.
查看更多>>摘要：Phosphorus is a limiting factor in agriculture due to restricted availability in soil and low utilization effi-ciency of crops. The identification of superior haplotypes of key genes responsible for low-phosphate (Pi) tolerance and their natural variation is important for molecular breeding. In this study,we conducted genome-wide association studies on low-phosphate tolerance coefficients using 152 maize inbred lines,and identified a significant association between SNPs on chromosome 7 and a low-phosphate tolerance coefficient. ZmGRF10 was identified as a candidate gene involved in adaptation of maize to Pi starvation. Expression of ZmGRF10 is induced by Pi starvation. A mutation in ZmGRF10 alleviated Pi starvation stress. RNA-seq analyses revealed significant upregulation of genes encoding various phosphatases in the zmgrf10-1 mutant,suggesting that ZmGRF10 negatively regulates expression of these genes,thereby affecting low-Pi tolerance by suppressing phosphorus remobilization. A superior haplotype with varia-tions in the promoter region exhibited lower transcription activity of ZmGRF10. Our study unveiled a novel gene contributing to tolerance to low-Pi availability with potential to benefit molecular breeding for high Pi utilization.
查看更多>>摘要：Regulation of iron homeostasis in maize remains unclear,despite the known roles of FER-Like Fe deficiency-induced transcription factor (FIT) in Arabidopsis and rice. ZmFIT,like AtFIT and OsFIT,interacts with iron-related transcription factors 2 (ZmIRO2). Here,we investigate the involvement of ZmFIT in iron homeostasis. Mutant ZmFIT lines exhibiting symptoms of Fe deficiency had reduced shoot iron content. Transcriptome analysis revealed downregulation of Fe deficiency-responsive genes in the roots of a Zmfit mutant. ZmFIT facilitates the nuclear translocation of ZmIRO2 to activate transcription of down-stream genes under Fe-deficient conditions. Our findings suggest that ZmFIT,by interaction with ZmIRO2,mediates iron homeostasis in maize. Notably,the binding and activation mechanisms of ZmFIT resemble those in Arabidopsis but differ from those in rice,whereas downstream genes regulated by ZmFIT show similarities to rice but differences from Arabidopsis. In brief,ZmFIT,orthgologs of OsFIT and AtFIT in rice and maize,respectively,regulates iron uptake and homeostasis in maize,but with variations.
查看更多>>摘要：GTs (Glycosyltransferases) are important in plant growth and abiotic stresses. However,its role in maize heat response is far from clear. Here,we describe the constitutively expressed UDP-glycosyltransferase ZmUGT92A1,which has a highly conserved PSPG box and is localized in chloroplasts,is induced under heat stress. Functional disruption of ZmUGT92A1 leads to heat sensitivity and reactive oxygen species accumulation in maize. Metabolomics analysis revealed that ZmUGT92A1 affected multiple metabolic pathways and altered the metabolic homeostasis of flavonoids under heat stress. In vitro assay showed ZmUGT92A1 exhibits glycosyltransferase activity on flavonoids and hormones. Additionally,we identified a rapidly heat-induced transcription factor,ZmHSF08,which can directly bind and repress the promoter region of ZmUGT92A1. The ZmHSF08 overexpression line exhibits heat sensitivity and reactive oxygen species accumulation. These findings reveal that the ZmHSF08-ZmUGT92A1 module plays a role in heat tolerance in maize and provide candidate strategies for the development of heat-tolerant varieties.
查看更多>>摘要：Plant Homeo Domain (PHD) proteins are involved in diverse biological processes during plant growth. However,the regulation of PHD genes on rice cold stress response remains largely unknown. Here,we reported that PHD17 negatively regulated cold tolerance in rice seedlings as a cleavage target of miR1320. PHD17 expression was greatly induced by cold stress,and was down-regulated by miR1320 overexpression and up-regulated by miR1320 knockdown. Through 5'RACE and dual luciferase assays,we found that miR1320 targeted and cleaved the 3'UTR region of PHD17. PHD17 was a nuclear-localized protein and acted as a transcriptional activator in yeast. PHD17 overexpression reduced cold tolerance of rice seedlings,while knockout of PHD17 increased cold tolerance,partially via the CBF cold signaling. By combining transcriptomic and physiological analyses,we demonstrated that PHD17 modu-lated ROS homeostasis and flavonoid accumulation under cold stress. K-means clustering analysis revealed that differentially expressed genes in PHD17 transgenic lines were significantly enriched in the jasmonic acid (JA) biosynthesis pathway,and expression of JA biosynthesis and signaling genes was verified to be affected by PHD17. Cold stress tests applied with MeJA or IBU (JA synthesis inhibitor) further suggested the involvement of PHD17 in JA-mediated cold signaling. Taken together,our results suggest that PHD17 acts downstream of miR1320 and negatively regulates cold tolerance of rice seedlings through JA-mediated signaling pathway.
查看更多>>摘要：A rice low temperature-induced albino variant was determined by the recessive ltia1 and ltia2 genes. LTIA1 and LTIA2 encode highly conserved mini-ribonucleases Ⅲ located in chloroplasts and expressed in aerial parts of the plant. At low temperature,LTIA1 and LTIA2 redundantly affect chlorophyll levels,non-photochemical quenching,photosynthetic quantum yield of PS Ⅱ and seedling growth. LTIA1 and LTIA2 proteins are involved in splicing of atpF and the biogenesis of 16S and 23S rRNA in chloroplasts. Presence/absence variation of LTIA1,the ancestral copy,was found only in japonica but that of LTIA2 in all rice subgroups. Accessions with LTIA2 presence tended to be distributed more remote from the equa-tor compared to those with LTIA2 absence. LTIA2 duplicated from LTIA1 at the early stage of divergence of the AA genome Oryza species but deleted againin O. nivara. In cultivated rice,absence of LTIA2 is derived from O. nivara. LTIA1 absence occurred more recently in japonica.
查看更多>>摘要：Maintenance of ion homeostasis in plant cells is an essential physiological requirement for sustainable growth,development,and yield of crops. Plants respond to high levels of heavy metals such as copper (Cu) and cadmium (Cd) to avoid irreversible damage at the structural,physiological and molecular levels. Our previous study found that rice germin-like proteins (OsGLPs) are a type of Cu-responsive proteins. The deletion of 10 tandem OsGLP genes on chromosome 8 led to more severe heavy metal toxicity in rice. In this study,we show that rice WRKY transcription factor OsWRKY72 negatively regulates OsGLP8-7 transcription. Overexpression of OsWRKY72 weakens the Cu/Cd tolerance of rice when exposed to Cu and Cd. OsWRKY72 suppressed expression of OsGLP8-7 and lignin synthesis genes,resulting in reduced lignin polymerization and consequently lower lignin accumulation in cell walls,thereby increasing the Cu and Cd accumulation. In addition,OsWRKY53 bound to OsWRKY72 to alleviate the transcriptional inhibition of OsGLP8-7. These results revealed that OsWRKY72-OsGLP8-7 is an important module response of rice to heavy metal stress,and that transcription factor OsWRKY72 acts upstream of OsGLP8-7 to regulate Cu/Cd toxicity.
查看更多>>摘要：Aluminum (Al) toxicity poses a significant constraint on field crop yields in acid soils. Zinc finger protein 36 (ZFP36) is well-documented for its pivotal role in enhancing tolerance to both drought and oxidative stress in rice. This study unveils a novel function of ZFP36 modulated by abscisic acid (ABA)-dependent mechanisms,specifically aimed at alleviating Al toxicity in rice. Under Al stress,the expression of ZFP36 significantly increased through an ABA-dependent pathway. Knocking down ZFP36 heightened Al sensi-tivity,while overexpressing ZFP36 conferred increased resistance to Al stress. Additionally,our investiga-tions revealed a physical interaction between ZFP36 and pyruvate dehydrogenase kinase 1 in rice (OsPDK1). Biochemical assays further elucidated that OsPDK1 phosphorylates ZFP36 at the amino acid site 73-161. Subsequent experiments demonstrated that ZFP36 positively regulates the expression of ascorbate peroxidases (OsAPX1) and OsALS1 by binding to specific elements in their upstream segments in rice. Through genetic and phenotypic analyses,we unveiled that OsPDK1 influences ABA-triggered antioxidant defense to alleviate Al toxicity by interacting with ZFP36. In summary,our study underscores that pyruvate dehydrogenase kinase 1 (OsPDK1) phosphorylates ZFP36 to modulate the activities of antioxidant enzymes via an ABA-dependent pathway,influencing tolerance of rice to soil Al toxicity.
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