Transcriptional regulation of chlorophyll-catabolic genes associated with exogenous chemical effects and genotypic variations in heat-induced leaf senescence for perennial ryegrass
Transcriptional regulation of chlorophyll-catabolic genes associated with exogenous chemical effects and genotypic variations in heat-induced leaf senescence for perennial ryegrass
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多年生黑麦草热诱导叶片衰老与外源化学效应和基因型变异相关的叶绿素分解代谢基因的转录调控
DOI：
10.1016/j.envexpbot.2019.103858
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发表时间：
2019
影响因子：
5.7
通讯作者：
Huang Bingru
中科院分区：
文献类型：
--
作者：
Zhang Jing;Xing Jing;Lu Qiyu;Yu Guohui;Xu Bin;Huang Bingru
热诱导的叶片衰老以加速叶绿素(Chl)分解代谢为特征。有关Chl分解代谢基因(CCGs)参与热诱导叶片衰老的研究还不是很清楚。本研究的目的是研究多年生黑麦草(Lolium perenneL.)叶片衰老过程中与外源化学效应和基因变异相关的CCGs的转录变化，并探讨其可能的机制。对耐热性不同的两种多年生黑麦草‘Buena vista’和‘Pinnacle’的生长室内和叶片喷施化学物质：水杨酸(SA)、6-苯氨基嘌呤(6-BA；细胞分裂素)、二氯化钙(CaCl2)、氨基乙氧基乙烯基甘氨酸(AVG)、硝普钠(SNP)和尿素(N，氮源)，分别在35/30°C(昼夜)和25/20 °C(昼夜)条件下进行高温胁迫处理。在高温胁迫下，‘Buena Vista’的Chl含量、光化学效率和细胞膜稳定性均高于‘Pinnacle’，而LpNYC1、LpNOL和LpPPH的表达水平较低。外源SA、6-BA、CaCl2、AVG、SNP和N抑制了热胁迫下热敏型‘顶峰’叶片Chl含量的下降和CCGs的表达。这些化合物显著降低了活性氧(ROS)的含量和提高了ROS清除酶的活性，从而减轻了热诱导的氧化损伤。CCGs的表达水平与O2、−、H2O2等ROS水平呈负相关，与过氧化氢酶、超氧化物歧化酶等ROS清除酶活性呈正相关。这些结果表明，LpNYC1、LpNOL和LpPPH基因的转录水平与多年生黑麦草的叶片衰老呈负相关，下调CCGs基因可以抑制多年生黑麦草叶片的衰老和氧化损伤，增强多年生黑麦草的耐热性。
Heat-induced leaf senescence is hallmarked with accelerated chlorophyll (Chl) catabolism. The involvement of Chl catabolic genes (CCGs) in heat-induced leaf senescence is not well characterized. The objectives of this study were to investigate transcriptional changes in CCGs associated with exogenous chemical effects and genotypic variations during heat-induced leaf senescence in perennial ryegrass (Lolium perenneL.), and to characterize its underlying mechanisms. Perennial ryegrass plants of ‘Buena Vista’ and ‘Pinnacle’ differing in heat tolerance were exposed to heat stress at 35/30 °C (day/night) and control condition at 25/20 °C (day/night) in growth chambers and foliar sprayed with the following chemicals: salicylic acid (SA), 6-benzylaminopurine (6-BA; a cytokinin), calcium dichloride (CaCl2), aminoethoxyvinylglycine (AVG; an ethylene biosynthesis inhibitor), sodium nitroprusside (SNP, a nitric oxide donor), and urea (N, nitrogen source). Higher Chl content, photochemical efficiency and membrane stability were found in ‘Buena Vista’ than ‘Pinnacle’ whereas lower expression levels of three CCGs (LpNYC1,LpNOL, andLpPPH) were detected in the former genotype under heat stress. Exogenous application of SA, 6-BA, CaCl2, AVG, SNP, and N suppressed heat-induced Chl decline and expression of CCGs in heat sensitive genotype ‘Pinnacle’ under heat stress. Heat-induced oxidative damage was alleviated by these compounds, as indicated by significantly lower reactive oxygen species (ROS) content and higher activities of ROS scavenging enzymes. The expression levels of CCGs were negatively correlated to ROS level, including O2−and H2O2, while positively correlated to activities of ROS scavenging enzymes, such as CAT and SOD. The current results suggest that the transcript levels ofLpNYC1,LpNOL, andLpPPHwere negatively correlated with heat-induced leaf senescence, and down-regulation of CCGs genes could suppress heat-induced leaf senescence and oxidative damages, conferring heat tolerance in perennial ryegrass.