黄瓜属人工异源四倍体幼叶黄化分子机制研究

Allopolyploidy is not only an important process in plant evolution, but also an efficient approach of crop breeding. If the fusion of sub-genomes in allopolyploid generates adverse phenotypic variation, the further exploration and utilization of polyploids will be hampered. The artificial allotetraploid in Cucumis is an essential resource for cucumber genetic improvement via broadening the genetic basis, but it exhibits phenotypic variation of yellowish young leaves. And the breeding materials obtained from it also showed different degrees of yellowing, which limits the cucumber variety improvement via interspecific variation. The applicant’s previous study demonstrated that the deficiency of chlorophylls in the young leaves was closely related to the non-additively down regulation of redundant homoeologous chlorophyll biosynthetic key genes. However, the underlying molecular mechanism regulating the biosynthesis and metabolism of chlorophylls and carotenoids remains unclear. Based on these, the current project is going to carry out carotenoid biosynthesis and metabolism analysis, and to globally uncover key factors that regulate the biosynthesis and metabolism of chlorophylls and carotenoids in young leaves of the allotetraploid through transcriptome-proteome joint analysis, and further to validate their functional mode, thus, to comprehensively illuminate the molecular mechanism of the formation of yellowish young leaves of the allotetraploid in Cucumis. The outcome will lay the foundation for efficient use of the allotetraploid for cucumber variety improvement and will enrich the knowledge of phenotypic variation caused by polyploidization as well.

异源多倍体化是植物进化的重要进程，也是作物育种的有效途径。如果异源多倍体中亚基因组的融合产生不利的表型变异，就会阻碍多倍体的进一步研究与利用。黄瓜属人工异源四倍体是拓宽遗传基础用于黄瓜遗传改良的重要资源，但其幼叶出现黄化的表型变异，包括由其衍生的育种材料也出现不同程度的黄化，成为制约利用种间变异改良黄瓜品种的瓶颈。申请者前期研究表明，异源四倍体幼叶叶绿素的缺乏与冗余的部分同源叶绿素生物合成关键基因的非加性下调表达密切相关。然而，调控异源四倍体幼叶叶绿素与类胡萝卜素合成代谢的内在分子机制仍不清楚。本项目拟在此基础上开展类胡萝卜素合成代谢分析，通过转录组-蛋白组关联分析全面筛选调控异源四倍体幼叶叶绿素与类胡萝卜素合成代谢的关键因子，并验证其作用方式，从而阐明黄瓜属异源四倍体幼叶黄化形成的分子机制。研究结果可为有效利用异源四倍体进行黄瓜品种改良奠定基础，同时加深对异源多倍体化引起表型变异的认识。

异源多倍体化是植物进化的重要进程，也是作物育种的有效途径。如果异源多倍体中亚基因组的融合产生不利的表型变异，就会阻碍多倍体的进一步研究与利用。黄瓜属人工异源四倍体是拓宽遗传基础用于黄瓜遗传改良的重要资源，但其幼叶出现黄化的表型变异，包括由其衍生的育种材料也出现不同程度的黄化，成为制约利用种间变异改良黄瓜品种的瓶颈。申请者以黄瓜属异源四倍体及其二倍体亲本为研究材料，全面比较分析了其表型变化，阐明黄瓜异源四倍体表型变化特征；通过分析不同发育时期叶片的类胡萝卜素合成代谢相关组分含量变化，明确了异源四倍体幼叶黄化直接相关的光合色素组分差异；利用多种测序技术破译甜瓜属异源四倍体基因组序列，发现了显著的亚基因组优势现象，并阐明了种间杂交在黄瓜异源多倍化过程中的主导作用，同时，对异源四倍体黄瓜的耐热和抗根结线虫能力进行了鉴定与分析，建立了黄瓜异源多倍体作物新类型快速培育框架模型；通过转录组测序与分析，构建了黄瓜异源四倍体基因与非编码RNA表达调控网络；分析了叶绿体基因组信息，建立了黄瓜异源四倍体核质共进化模型；利用蛋白组测序与分析，鉴定了异源四倍体黄瓜特异的差异表达蛋白，并进行了功能注释与富集分析，初步阐明了黄瓜属异源四倍体幼叶黄化表型变异产生的分子机制。研究结果为有效利用异源四倍体进行黄瓜品种改良奠定基础，同时加深了对异源多倍体化引起表型变异的认识。