田间条件下不同棉花品种叶片响应化学脱叶剂噻苯隆的转录组分析

Transcriptome analysis of different cotton varieties' leaves in response to chemical defoliant agent thidiazuron under field conditions

噻苯隆是棉花脱叶的主要化学药剂,在实现棉花机械采收中发挥了关键作用。目前,噻苯隆在大田环境下诱导棉花叶片脱落的分子调控机制研究较少。本研究以噻苯隆敏感型品种(冀丰914)和不敏感型株系(04-1685)为材料,测定叶片的乙烯、细胞分裂素和脱落酸含量,同时利用RNA-seq技术,分析噻苯隆处理后0 d、1 d、3 d、5 d叶片的基因表达变化,利用WGCNA(Weighted gene coexpression network analysis)分析筛选基因共表达模块,利用GO和KEGG分析基因功能。结果表明,冀丰914的乙烯、细胞分裂素和脱落酸含量在处理后1 d达到最高,04-1685的激素含量在处理后3 d达到最高。通过RNA-seq筛选到33,283个差异表达基因(differentially expressed genes,DEGs),通过WGCNA分析,分别筛选到2个和3个与激素和样本高度相关的模块,模块内的基因主要参与非生物胁迫响应、昼夜节律、物质代谢等过程。通过分析植物激素、胁迫响应、昼夜节律等主要过程相关基因的表达量发现,激素相关基因在敏感型品种冀丰914中的表达量更高,其中乙烯信号响应基因在处理后5 d内均保持在较高的表达水平,脱落酸信号响应基因在处理后1 d内保持较高的表达水平,细胞分裂素代谢相关基因在处理后1 d内表达量很低,处理后3 d和5 d的表达量急剧增加。处理后1 d和3 d,热激蛋白基因(HSP70、HSP90、ATJ3)、钙稳态调控基因(CRT3、NCL)和节律基因(LNK2、APRR9、CCA1)显著下调表达,节律基因(ARR8)上调表达。大田环境下喷施噻苯隆,在引起激素含量变化的同时,可能破坏了植物的昼夜节律、降低对非生物胁迫的应激能力,从而加速叶片衰老和脱落。本研究为丰富噻苯隆诱导叶片脱落的分子调控机制提供了更多思路。

Thidiazuron(TDZ)is the main chemical agent for cotton defoliation,which plays a key role in realizing cotton me-chanical harvesting.At present,there are few studies on the molecular regulation mechanism of TDZ induced cotton leaf abscis-sion in the field environment.In this study,TDZ sensitive variety(Jifeng 914)and non-sensitive line(04-1685)were used as the experimental materials.Ethylene,cytokinin,and abscisic acid contents in leaves were determined.RNA-seq was used to analyze the changes of gene expression in leaves at 0,1,3,and 5 d after TDZ treatment.WGCNA(Weighted gene coexpression network analysis),GO and KEGG were used to analyze and screen gene coexpression modules and gene functions,respectively.The re-sults showed that the ethylene,cytokinin,and abscisic acid contents of Jifeng 914 reached the highest level at 1 d after treatment,and the hormone contents of 04-1685 reached the highest level at 3 d after treatment.A total of 33,283 differentially expressed genes(DEGs)were screened by RNA-seq.Through WGCNA analysis,2 and 3 modules highly related to hormone and samples were screened respectively.The genes in the modules mainly participate in abiotic stress response,circadian rhythm,and material metabolism.By analyzing the relative expression of plant hormone,stress response,and circadian rhythm related genes,the ex-pression of hormone related genes in sensitive variety Jifeng 914 was higher,among which ethylene signal response genes were kept at a higher expression level within 5 days after treatment,abscisic acid signal response genes were kept at a higher expression level within 1 day after treatment,and cytokinin metabolism related genes expressed very low within 1 day after treatment and increased sharply at 3 d and 5 d after treatment.At 1 d and 3 d after treatment,heat shock protein genes(HSP70,HSP90,and ATJ3),calcium homeostasis regulating genes(CRT3,NCL),and circadian rhythm genes(LNK2,APRR9,CCA1)were significantly down regulated,while circadian rhythm genes(ARR8)were up regulated.Spraying TDZ in the field environment,while causing changes in hormone content,may damage the plant’s circadian rhythm and reduce the stress ability to abiotic stress,and thus ac-celerating leaf senescence and abscission.This study provides more ideas for enriching the molecular regulation mechanism of TDZ induced leaf abscission.