大白菜与芥蓝杂交合成的菜用甘蓝型油菜的遗传研究

Natural and synthetic Brassica allopolyploid species, especially B. napus, are widely used as a model to study the genetic and epigenetic changes during the process of allopolyploidization. The similar phenotypes (such as enlarged roots and stems) exhibited by several Brassica species not only illustrate the convergent crop domestication, but also suggest that the hybridizations between two diploids with particular traits could produce synthetic Brassica allopolyploid to study the genetic mechanism of phenotype development. Synthetic B. napus allotetraploids were previously obtained through interspecific crosses between B. rapa ssp. pekinensis L. (genotype Chiifu with the genome sequenced) and B. oleracea var. alboglabra L., which showed the much enlarged stems and bolting stems with good taste than two parents, and had great potential as a new kind of vegetable. Herein, the phenotype, fertility and chromosome behavior will be investigate to reaveal genetic changes in the synthetic B. napus allotetraploids and derived inbred lines. Meanwhile, transcriptome analysis (including mRNA and smRNA) will also be performed to analyze the experssion patterns of homoeologous genes and the effect of smRNA-mediated methylation on homoeolog expression bias. Together, our our study might reveal the genetic mechanism of new phenotypes in this vegetable B. napus.

天然及人工合成的芸苔属异源多倍体特别是甘蓝型油菜被广泛用于研究异源多倍化过程相关的遗传及表观遗传变化。部分芸苔属物种均表现出的相似特异形态（如膨大的根、茎）不但显示趋同的作物驯化，而且也启示我们可利用具有特殊表型的二倍体杂交合成新型的多倍体材料、研究性状形成的遗传机制。我们前期通过测序大白菜“Chiifu”与芥蓝的杂交合成的甘蓝型油菜表现显著增粗的茎及苔、口感脆且甜，可望培育成一种新型蔬菜。本项目将研究该甘蓝型油菜连续自交后代的表型、育性和细胞学行为、DNA组成变化等；进行转录组（mRNA和smRNA）测序，分析两个亲本基因的表达及互作、smRNA介导的表观遗传修饰对同源基因表达（偏向性）的影响，揭示新性状与特性产生的遗传基础。

天然及人工合成的芸薹属异源多倍体特别是甘蓝型油菜被广泛用于研究异源多倍化过程相关的基因表达变化。部分芸薹属物种均表现出的相似特异形态启示我们可利用具有特殊表型的二倍体杂交合成新型的多倍体材料。本项目通过测序大白菜“Chiifu”与芥蓝的杂交合成的甘蓝型油菜，发现人工合成甘蓝型油菜抽苔后苔茎相比双亲的明显增粗，鲜重明显高于双亲；对合成甘蓝型油菜进行营养成分进行测定，发现其可溶性糖，维生素C，叶绿素及可溶性蛋白含量较高，具备作为蔬菜应用的潜质；对人工合成甘蓝型油菜自交株系进行花粉育性观察，发现大部分株系花粉育性较好，推测导致合成甘蓝型油菜自交结实性较差的主要原因是自交不亲和；对不同合成甘蓝型油菜中同源基因表达分析表明，同源基因表达在杂交、染色体加倍、进化/驯化过程中表现出动态变化，来自不同基因组上反式作用因子调控存在差异，可能导致同源基因表达偏向性。