乙烯调控菜心木质素生物合成的生物学机制研究

The lignification is an important senescing phenomenon of post-harvest fruits and vegetables, which seriously affected storage quality of the fruit and vegetable products, and is also one of main problems of postharvest biology research. Our preliminary research results show that the TsaiTai was easy to be lignification, and ethylene played an important role in this process, but the mechanism is not clear. The proposal will choose TsaiTai which were easy to be lignification, and investigate the formation and regulation of lignin by ethylene. First The gene family members of lignin biosynthesis enzymes in response to ethylene will be obtained by RNA-seq in TsaiTai. We will figure out the effect of treatments of ethylene and 1-MCP on gene expression of lignin biosynthesis enzyme, enzyme activity and lignin content in harvested TsaiTai plants. The project research will enrich the theoretical system of the fruit and vegetable lignin synthesis , and also provide a new theoretical basis for the control technology of postharvest fruits and vegetables lignification.

木质化是采后果蔬衰老的重要现象之一，严重影响果蔬产品的贮藏品质，是采后生物学领域研究的主要问题之一。前期研究结果表明，采后菜心极易木质化，乙烯起重要的调控作用，但其机制尚不明确。本项目拟以菜心为研究材料，研究乙烯调控菜心木质素生物合成的机制。首先筛选响应乙烯的木质素合成关键酶基因家族成员，明确外源乙烯及乙烯信号转导抑制剂等处理对采后菜心木质素合成相关的基因表达、酶活性和木质素含量变化的影响。项目研究成果将丰富果蔬木质素合成的理论体系，也为采后果蔬木质化的控制技术提供新的理论依据。

本项目进行了乙烯信号转导对菜心木质素生物合成调控的研究。首先对采后菜心分别进行了乙烯和1-MCP处理，然后通过转录组测序和荧光定量PCR的方法确定了木质素合成途径受乙烯信号调控的基因，并进行了木质素含量和木质素合成相关酶活性测定。转录组测序结果表明，乙烯信号主要调控了木质素合成途径POD基因的表达，发现有7个POD基因转录本和1个CAD基因转录本受到了诱导，其它木质素合成基因转录本丰度没有发生改变，qPCR也印证上述结果。采后菜心木质素含量和相关酶活性测定表明，乙烯处理后茎部总木质素含量明显提高约提高10-15%，1-MCP处理后降低木质素含量20%，而成熟叶片的木质素含量变化不显著。为了进一步确定乙烯对木质素合成的调控，进行了乙烯诱导菜心幼苗木质素合成试验，结果表明，乙烯处理提高了幼苗茎、叶中POD酶活，并且随着乙烯浓度的提高而升高。对于木质化程度高幼根，乙烯处理提高了幼根POD酶活，1-MCP抑制了该酶活，提高H2O2含量，但是PAL、4CL、C4H等酶活性变化不明显。