采后黄瓜响应低温胁迫的转录组学分析

Transcriptomic Analysis of Harvested Cucumber in Response to Cold Stress

采后黄瓜对低温敏感,在低温贮藏期间很容易发生冷害,会造成较大的采后损失。本研究采用转录组测序结合生物信息学分析的方法,分析了采后黄瓜在短时冷害温度处理后的转录组变化。结果显示,采后黄瓜在5℃贮藏期间,冷害指数和相对电导率逐渐增加,叶绿素荧光逐渐降低,表明采后黄瓜在5℃贮藏期间产生了明显的冷害。与处理前相比(0 h),处理12 h导致1500个基因差异表达,其中706个基因表达上调,794个基因表达下调。与0 h相比,处理72 h导致7799个基因差异表达,其中3995个基因表达上调,3804个基因表达下调。KEGG富集结果显示,低温处理导致的差异表达基因显著富集在植物激素信号转导、苯丙氨酸代谢、植物与病原菌互作和苯丙烷素合成途径中。GO富集分析的结果显示,在生物过程分类下,差异表达基因主要参与以DNA为模板的转录调控、蛋白磷酸化和跨膜转运等过程;在细胞组份分类下,差异表达基因主要富集在细胞膜组份和细胞核;在分子功能分类下,差异表达基因主要与ATP结合、蛋白苏氨酸/丝氨酸激酶活性、DNA结合和转录因子活性等功能有关。在低温处理12 h时,与激素信号有关的基因显著表达。但在低温处理72 h时,与植物-病原菌互作以及苯丙烷素合成有关的基因被显著诱导,表明植物激素参与了早期的低温信号传递,诱导病程相关基因表达以及苯丙烷素合成可能是采后黄瓜提高耐冷性,应对低温胁迫的重要机制。本研究结果为采后黄瓜适应低温胁迫,并对低温胁迫作出抗性的分子机理提供了新见解,也为耐冷黄瓜新品种培育提供了重要基因资源。

Harvested cucumber is sensitive to low temperature,which is subjected to chilling injury during cold storage and causes heavy postharvest losses.In this study,the method of RNA sequencing combined with bioinformatics analysis was used to analyze the transcriptomic changes of harvested cucumber when subjected to a short-term of cold treatment.The chilling injury index(CⅡ)and relative electrical conductivity(REC)gradually increased but the chlorophyll fluorescence(Fv/Fm)decreased with increasing time when stored at 5℃,indicating that the chilling injury was obviously occurred.Compared with that before treatment(0 h),treatment at 5℃for 12 h resulted in 2679 differentially expressed genes(DEGs),of which 1194 DEGs were up-regulated and 1485 DEGs were down regulated.Compared with treatment for 0 h,treatment for72 h resulted in 9494 DEGs,of which 4807 DEGs were up-regulated and 4687 DEGs were down regulated.The results of KEGG enrichment analysis showed that the DEGs caused by cold treatment were most significantly enriched in the pathways of plant hormone signal transduction,phenylalanine metabolism,plant pathway interaction and phenylpropanoid biosynthesis.The results of GO enrichment analysis showed that DEGs were mainly involved in regulation of transcription DNA templated,protein phosphorylation and transmembrane transport in biological process.In cellular component,most enriched DEGs were related to organelle components such as membrane and nucleus.In molecular function,the enriched DEGs were mainly involved in ATP binding,protein serine/threonine kinase activity,DNA binding and transcription factor activity.DEGs related to hormone signal were significantly expressed when cucumber fruits were cold-treated for 12 h.However,the DEGs related to plant pathogen interaction and phenylpropanoid synthesis were significantly induced following 72 h of cold treatment.The results showed that plant hormone participated in the transmission of low temperature signals,the induced pathogenesis-related gene and phenylpropanoid biosynthesis might be important mechanisms for harvested cucumbers to improve chilling tolerance and cope with chilling stress.The results would provide new insights into the molecular mechanisms of harvested cucumber adaptation and resistance to chilling stress,and identify a lot of key gene resources for breeding cold-tolerant cucumber.