转录因子MYB介导的枇杷果实采后木质化及其调控机制研究

Loquat (Eriobotrya japonica Lindl.), a fruit with unique flavor, is a subtropical fruit originated from China. Postharvest fruit is chilling sensitive and develops fresh lignification with deterioration of fruit qualities such as browning and rot during long term of cold storage. The present project will focus on regulation of transcription factor MYB in fresh lignification, which is based on our decade's study in postharvest loquat fruit. EjMYB genes will be isolated by deep sequencing technology and their co-expression pattern in relation to lignin biosynthesis will be investigated for identification of key EjMYB gene(s) and its (their) target gene(s) involved in lignin biosynthesis. Further regulation mechanism of EjMYB(s) and the target gene(s) will be studied by yeast hybrid system and dual-luciferase system, and confirmed by transient assay and transgenic study. The results of the present project will provide new targets for manipulation of loquat fruit lignification and provide new evidence for improving postharvest technology of the loquat industry.

枇杷是我国特色水果，风味独特，但果实冷藏过程中易出现冷害木质化，并伴随褐变等品质劣变，腐烂损耗加剧，商品性迅速丧失。本项目拟在前期研究基础上，进一步利用深度测序技术分离差异表达的转录因子MYB家族成员，通过协同表达模式分析确认参与木质素代谢的EjMYB候选成员，采用双荧光素酶体系、酵母杂交技术、瞬时表达和转基因等手段明确并验证可转录调控木质素代谢靶标基因的EjMYB成员，并阐明EjMYB对枇杷果实采后木质素合成的调控机制。项目研究旨在为利用生物技术手段调控枇杷果实采后木质化等品质劣变提供新靶标，并为改善枇杷果实采后技术体系提供新依据。

红肉品种枇杷果实采后易发生木质化，且低温贮藏还可加速木质化进程。MYB是调控木质素代谢的重要转录因子基因家族，但在枇杷果实中它们的调控效应仍鲜见报道。本项目以‘洛阳青’枇杷为材料，重点关注了MYB对果实木质化的调控效应。分析了热处理（HT）和程序降温处理（LTC）对果实木质化的调控效应，利用上述材料开展了转录组测序；基于转录组测序结果结合同源克隆策略，先后克隆得到14个EjMYB成员，分别命名为EjMYB1-14；利用双荧光素酶、酵母单杂、瞬时表达等体系，明确了EjMYB1/2/8通过调控Ej4CL1影响果实木质化；基于测序还发现了EjHSF-EjAP2-EjMYB转录因子复合体参与枇杷果实木质化调控；利用EjMYB8启动子的酵母单杂筛库，发现了EjMADS可以结合并抑制EjMYB8启动子，因此MADS-MYB级联转录调控效应也参与了枇杷果实木质化。这些结果，不仅明确了调控枇杷果实木质化的EjMYB成员，同时还创新了MYB调控木质素代谢的多种不同机制。项目研究成果已在J Exp Bot、Plant Cell Environ、PLOS ONE、HortScience等刊物发表SCI论文5篇（其中IF>5.0论文3篇），培养研究生8名，已按项目合同完成各项任务指标。