油茶叶片愈伤组织油脂生物合成的去抑制调控研究

Most embryogenic genes which has the ability to induce lipid biosynthesis, such as LEC1/B3 master regulators in plant vegetative tissues, are suppressed by only a few PcG genes and HDAC. PcG proteins can trigger trimethylation of histon H3 lysine 27 at loci of many embryogenic genes, and maintain the levels of this trimethylation in vegetative tissues, therefore, the embyogenic genes including LEC1/B3 factors, which are not needed for vegetative development, are repressed, whereas a part of HDAC also inhibit embryogenic genes in vegetative tissues via condensing of chromatin. It has been found that somewhate degree of oil existed in the callus of Camellia oleifera, So we decide to perform RNAi against PcG genes and HDAC of C.oleifera to release the expression activities of subsets of embryogenic and lipid biosynthesis-related genes, therefore the oil content in the calli of C.oleifera can be increased markedly.Using the background material of PKL:RNAi, the RNAi against genes of interest are performed, and the so-called single repressive RNAi calli that share potential traits of lipogenesis will be screened out. The seedlings can be induced from these calli, and further be transgened by introducing the dsRNA constructs of paralogs in relation to the PcG genes or HDAC which has been introduced. In this way, double repressive RNAi calli with more significant traits of lipogenesis will be obtained. Among a series of RNAi calli with different oil content, by comparing the difference of DNA methylation, histone modifications at the loci of LEC and oleosin, which are upstream and downstream respectively in the case of lipid biosynthesis, in combination with the difference of expression between PcG genes, HDAC, LEC1/B3, WRI1, oleosin, the epigenetics mechanism for lipogenesis or embryogenesis in calli of C.oleifera will be elucidated.

植物营养组织中诱导油脂生物合成的LEC1/B3胚性主调节子等一系列的基因受少数PcG基因与HDAC的抑制。PcG蛋白能引发并维持这些胚性基因位点的H3K27me3而抑制其表达；部分HDAC则是使染色质浓缩而抑制胚性基因的表达。笔者发现油茶愈伤组织含有一定油分，拟对油茶PcG基因、HDAC进行RNAi以释放愈伤组织中一系列成套的成脂/胚成基因的表达，提高其含油率。以PKL:RNAi株系为背景对各目的基因进行RNAi，筛选到有成脂潜力的单抑制RNAi愈伤系，诱导成苗；进而抑制该株系的旁系同源基因，筛选到成脂表型显著的双抑制RNAi株系。选择油脂生物合成相关的上游LEC、下游oleosin，比较不同含油率的愈伤组织中它们的DNA甲基化、所处位点组蛋白修饰的差异，结合油茶PcG基因、HDAC与LEC1/B3、WRI1、oleosin表达之间的相关性分析，阐明油茶愈伤组织成脂的表观遗传学调控机。