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.
This paper was conducted to explore the effects of melatonin(MT)on the senescence of stored Chinese flowering cabbage and the potential modulatory mechanisms involved.The physiological findings demonstrated that MT successfully reduced chlorophyll loss and improved the photochemical effectiveness of cabbage leaves.In addition,MT decreased the transcription of senescence-associated genes(BrSAG12)and genes responsible for chlorophyll breakdown.Transcriptome analysis showed that MT-regulated genes were enriched in oxidative phosphorylation,hormone metabolism and signal transduction,and MT treatment reduced the high expression of genes linked to generation of reactive oxygen species(ROS),energy metabolism,phytohormone(abscisic acid(ABA),ethylene(ET),and jasmonic acid(JA))biological synthesis and signal transduction while promoting the activation of genes related to scavenging ROS,energy biosynthesis and plant–pathogen interactions.We emphasized the examination of the potential interaction between phytohormone metabolism and MT.The results showed that the application of MT decreased ABA,ET,and JA levels as well as the expression of their biosynthesis genes,concurrently maintaining higher expression of cytokinin,auxin and gibberellin biosynthetic genes and lower expression of degradation genes.Regulatory networks of transcription factors(TFs)and genes related to ABA,ET and JA metabolism showed that TFs such as DNA-binding One Zinc Finger 5.7(DOF5.7),WRKY40,and homeobox-leucine zipper protein-16(ATHB-16)might play important transcriptional regulatory roles in mediating MT postponed leaf senescence.Taken together,these findings suggested that the postponed senescence of cabbage treated with MT might be ascribed to the regulated oxidative phosphorylation,energy,phytohormone metabolism,and transcription factors.
High temperatures cause physiological and biochemical changes and significantly affect young panicle development of rice(Oryza sativa L.).Brassinosteroids play important roles in enhancing crop stress resistance.In this study,we subjected rice cultivars Huanghuazhan(heat-resistant)and IR36(heat-sensitive)to high temperature(HT,40 oC)or normal temperature(NT,33 oC)for 7 d at the panicle initiation stage,in conjunction with application of 24-epibrassinolide[EBR,a synthetic brassinolide(BR)]or brassinazole(BRZ,a BR biosynthesis inhibitor)at the beginning of the treatments.HT exacerbated spikelet degeneration and inhibited young panicle growth,which were partially prevented by EBR application,while BRZ application aggravated the reduction in spikelet number.HT decreased the contents of BR,active cytokinins(aCTK),active gibberellins(aGA)and indole-3-acetic acid(IAA),but increased the content of abscisic acid(ABA)in young panicles.The activities of key enzymes involved in sucrose hydrolysis,glycolysis and the tricarboxylic acid cycle in young panicles were decreased with the change of endogenous hormone levels under HT.In addition,the contents of H2O2 and malondialdehyde(MDA)were increased and the activities of antioxidant enzymes were decreased in young panicles.Exogenous application of EBR induced the expression of phytohormone biosynthesis-related genes and down-regulated the expression of phytohormone catabolism-related genes to increase the contents of endogenous BR,aCTK,aGA and ABA,thus promoting the decomposition and utilization of sucrose in young panicles,enhancing the activities of superoxide dismutase,catalase and peroxidase,and reducing the accumulation of H2O2 and MDA in young panicles,whereas application of BRZ had the opposite physiological effects.These results showed that brassinosteroids mediate endogenous phytohormone metabolism to alleviate HT injury at the panicle initiation stage in rice.
