玉米基因Dirigent protein 4的克隆和功能鉴定

玉米的次级代谢物可导致植株抗性增强，同时次级代谢物如木脂素等在籽粒中的积累可赋予其特殊的生物活性。发掘玉米中特殊次级代谢物的调控基因，鉴定其作用机制，具有很高的应用预期。玉米粒色表型是众多次级代谢产物积累共同导致的结果。项目组前期通过GWAS对1300份自然群体材料中的粒色表型进行分析，获得了与粒色表型相关性极高的QTL位点。结合基因组注释信息和转录组数据筛选候选基因，我们选择了Zm00001d034563作为本项目研究对象。该基因编码一个Dirigent protein 4(ZmDP4)蛋白，包含一个完整的Dirigent结构域。该蛋白家族被预测催化了木脂素代谢调控中的耦合作用，同时涉及到其他次级代谢物如生物碱的代谢过程。对此，我们设计了相关分子与生化实验，以验证其对木脂素等次生代谢物的调控行为，探索其对环境逆境的响应机制，鉴定互作蛋白网络，最终达到具体解释该基因功能的目的。

The secondary metabolites in maize can enhance resistance to environmental stress and amass of lignans in its kernel may produce special biological activities. So it can be highly applicable that the mechanism exploration of regulatory genes for the special secondary metabolites could have great significance for crop genetic improvement. Grain color is a complex phenotype that is determined by accumulation of multiple secondary metabolites. Our group has previously analyzed the grain color by GWAS across a natural group composed of 1300 maize inbred lines and discovered numerous QTLs that are significantly relevant to grain color phenotype. Through analyzing the candidate genes by functional annotation and transcriptome validation around the QTL sites, a Dirigent family gene Zm00001d034563 was selected as research focus on the basis of functional annotation. The gene encodes a Dirigent Protein 4 (ZmDP4) and contains a complete Dirigent domain. This protein family is predicted to be capable of catalyzing coupling in lignans anabolism and involving in other secondary metabolic process such as of alkaloids. Serious molecular and biochemical experiments were designed to explore the proteins’ regulation on lignans synthesis, their responding mechanism to environmental stress and interaction network, and ultimately the function of ZmDP4 was identified and expounded. This project will theoretically increase the current understanding of secondary metabolic regulation network and provide some guidance for breeding high secondary metabolites maize varieties.