Brassinosteroids(BRs)play a crucial role in regulating multiple biological processes in plants,particularly those related to crop productivity and stress tolerance.During their functioning,BRs engage in extensive and intricate interactions with other phytohormones,including auxin,cytokinins,gibberellins,abscisic acid,ethylene,jasmonates,salicylic acid,and strigolactones.These interactions facilitate the integration of internal and external signals,ultimately shaping the physiological status of the plant.In this review,we introduce BR metabolism and signaling and discuss their role in modulating agronomic traits that directly contribute to grain yield in rice(Oryza sativa),the model plant for crops.We also summarize recent advances in the crosstalk between BRs and other phytohormones in regulating agronomic traits in crops.Furthermore,we highlight significant research that provides insights into developing high-yielding and stressresistant crop varieties from the perspective of hormone crosstalk.Understanding the genetic and molecular mechanisms through which BRs and other phytohormones collaboratively control agronomic traits offers new approaches for crop improvement.
Viruses are significant pathogens causing severe plant infections and crop losses globally.The resistance mechanisms of rice to viral diseases,particularly Southern rice black-streaked dwarf virus(SRBSDV),remain poorly understood.In this study,we assessed SRBSDV susceptibility in 20 Xian/indica(XI)and 20 Geng/japonica(GJ)rice varieties.XI-1B accessions in the Xian subgroup displayed higher resistance than GJ accessions.Comparative transcriptome analysis revealed changes in processes like oxidoreductase activity,jasmonic acid(JA)metabolism,and stress response.JA sensitivity assays further linked antiviral defense to the JA pathway.These findings highlight a JA-mediated resistance mechanism in rice and offer insights for breeding SRBSDV-resistant varieties.
The oilseed crop Camelina sativa exhibits salinity tolerance,but the effects on early growth stages across a range of different salts and in combination with salicylic acid(SA)have not been thoroughly evaluated.In this study,seeds were germinated in varying concentrations of six salts(NaCl,CaCl_(2),ZnCl_(2),KCl,MgSO_(4),and Na2SO_(4))with or without 0.5 mM SA.Using the halotime model,we estimated salt thresholds for germination and parameters of seedling growth.Germination and seedling growth parameters of camelina significantly decreased with increasing salt concentration across all salt types.Salts containing Zn and SO_(4) were most detrimental to germination and seedling growth.Except for KCl,0.5 mM SA generally reduced the salinity tolerance threshold(Saltb(50))of camelina.Specifically,Saltb(50)was 21.5%higher for KCl and 16.1%,25.0%,54.9%,21.0%,and 5.6%lower for CaCl_(2),NaCl,MgSO_(4),Na2SO_(4),and ZnCl_(2),respectively,when 0.5 mM SA was compared to 0 mM SA.Furthermore,camelina seedling growth was consistently more sensitive than germination across all salt types.SA did not significantly enhance germination or seedling growth and was harmful when combined with certain salts or at the germination stage.It can be concluded that both the type of salt and the concentration of SA are as critical as the salt concentration in saline irrigation water.
Although numerous studies have focused on phytohormones in specific organs or tissues at different development stages or under various abiotic and biotic stress conditions,our understanding of the distribution and relative abundance of phytohormones throughout the entire life cycle of plants remains insufficient.Here,we present a phytohormone atlas resource obtained from the quantitative analysis of eight major classes of phytohormones,comprising a total of 40 hormone-related compounds,throughout the complete life cycle of wheat.In combination with transcriptome analysis,we established a wheat phytohormone metabolic regulatory network(WPMRN).Using the WPMRN dataset and Gene Ontology enrichment analysis,we swiftly characterized the function of TaLOG5-B1 in cytokinin biosynthesis.Furthermore,a detailed investigation of the WPMRN dataset uncovered transcription factor-mediated co-regulatory mechanisms among different classes of phytohormones.We focused specifically on the metabolic regulation of cytokinin and jasmonic acid,and functionally characterized the genes TaLOG3-D1 and TaAOS-D1 that are involved in the biosynthesis of these phytohormones,respectively,along with their regulatory transcription factor genes TaDOF3A and TaDOF5.6B.The functions of these genes were validated in transgenic plants,revealing their ability to co-regulate radicle length.These findings serve as a case study that highlights the utility of this resource for studying phytohormone metabolic regulatory networks in cereal crops and for gaining insights into the roles of phytohormones in enhancing agronomic traits.
Grain water content(GWC)is a key determinant for mechanical harvesting of maize(Zea mays).In our previous research,we identified a quantitative trait locus,qGWC1,associated with GWC in maize.Here,we examined near-isogenic lines(NILs)NILL and NILH that differed at the qGWC1 locus.Lower GWC in NILL was primarily attributed to reduced grain water weight(GWW)and smaller fresh grain size,rather than the accumulation of dry matter.The difference in GWC between the NILs became more pronounced approximately 35 d after pollination(DAP),arising from a faster dehydration rate in NILL.Through an integrated analysis of the transcriptome,proteome,and metabolome,coupled with an examination of hormones and their derivatives,we detected a marked decrease in JA,along with an increase in cytokinin,storage forms of IAA(IAA-Glu,IAA-ASP),and IAA precursor IPA in immature NILL kernels.During kernel development,genes associated with sucrose synthases,starch biosynthesis,and zein production in NILL,exhibited an initial up-regulation followed by a gradual down-regulation,compared to those in NILH.This discovery highlights the crucial role of phytohormone homeostasis and genes related to kernel development in balancing GWC and dry matter accumulation in maize kernels.
The plant defense hormone jasmonates not only play important roles in plant growth,development,and resistance,but also hold promise for bringing new strategies in plant protection and cancer therapy.Recently,de novo biosynthesis of natural and unnatural jasmonates in refactored yeast with integration of 15 heterologous genes and 3 native genes deleted was reported.Here,we highlight the feasible and sustainable platform to efficiently produce jasmonates,which would benefit both agriculture and human health.
