Abstract: Low temperature during growing season affects the development and yield of bitter gourd (Momordica charantia L.), which limits the geographical locations. In order to understand tolerance mechanism to cold stress of bitter gourd, inbred line NO.43 was tested under low temperature stress in this research. The phenotype, relevant physiological and biochemical indexes, and transcriptome of No.43 were observed and determined after cold stress treatment under 8℃. The main results are as follows: inbred line NO.43 showed cold tolerance under cold stress. In addition, the content of MDA, Pro, and REC(Relative electrolyte leakage rate)in bitter gourd significant changed under cold stress. The transcriptome under cold stress (8℃) treatments with 0 and 12 h is also analyzed. The results showed that in response to cold, a total of 1 285 differentially expressed genes (DEGs) were detected, including 916 up-regulated and 369 down-regulated genes. In addition, sone metabolism pathways involving a large number of candidate genes were identified to be regulated by cold. Moreover, 10 genes related to cold stress reported from other publications were also detected, including transcription factors of WRKY, NAC, MYB families. We validated the expression profiles of 10 candidates genes by qRT-PCR,the results are consistent with the phenotypic and physiological changes, which further confirmed the accuracy of RNA-seq results. In this study, the transcriptome changes of bitter gourd under low temperature stress, as well as the molecular mechanisms of dynamic changes and physiological responses to low-temperature-resistant genes were revealed at the genome-wide level. This study provides some insights into the cold tolerance mechanism and digging out useful candidate genes for genetic improvement.

Key words: Momordica charantia L., low temperature stress, transcriptome, transcription factor, expression analysis

摘要： 苦瓜在生长季节遇到低温会影响其生长发育和产量,限制了种植分布区域。为了研究苦瓜耐寒性的分子机制,本研究以苦瓜自交系43为试验材料,在8℃低温胁迫处理后观察其表型并测定相关生理生化指标,再利用转录组测序技术从生理角度结合分子水平对苦瓜低温胁迫机制进行生物信息学分析。结果表明,在8℃低温胁迫下,苦瓜表现出耐低温适应性,在低温胁迫下丙二醛(MDA)含量、脯氨酸含量及电解质渗透率均呈现显著变化。分析了低温胁迫0和12 h后的转录组变化,结果发现低温胁迫处理后有916个基因上调,369个基因下调。对差异表达基因进行通路注释分析,发现大量与低温胁迫相关的代谢途径。进一步筛选到10个在其他物种报道过可能与冷胁迫相关的基因,包括MYB、WRKY以及NAC转录因子等。对植物耐低温相关的候选基因进行了实时荧光定量PCR(qRT-PCR)表达谱分析,结果与生理表型变化相吻合,同时进一步证实了RNA-seq数据的准确性。本研究基于全基因组水平分析苦瓜在低温胁迫下的转录组变化,以及耐低温相关基因动态变化和生理反应的分子机制,为揭示苦瓜中的耐寒性机理和筛选遗传改良候选基因提供了一定基础。

关键词: 苦瓜, 低温胁迫, 转录组, 转录因子, 表达分析