小麦禾谷孢囊线虫(H. avenae, CCN)已成为我国麦类作物高产、稳产的重要限制因素之一。但小麦种内抗性资源匮乏，其相关抗性机理尚不清楚。本研究组通过禾谷孢囊线虫侵染易变山羊草的深度转录组测序，发现苯丙氨酸代谢及异喹啉生物碱代谢在整个抗性应答中具有重要作用，其中色氨酸脱羧酶为两代谢途径共有关键酶。因此，本项目拟通过对色氨酸脱羧酶基因（TDC）全序列克隆，揭示基因结构、亚细胞定位、基因表达特性；通过构建该基因植物根部特异表达载体对烟草及小麦遗传转化，评价其对禾谷孢囊线虫及根结线虫的抗性作用。通过对色氨酸脱羧酶（TDC）基因过表达或抑制表达（沉默），探索根部在CCN的侵染诱导下次生代谢产物的变化及与对根线虫抗性和表型性状发育的关系，揭示苯丙氨酸代谢及异喹啉生物碱代谢途径在小麦抗禾谷孢囊线虫，乃至植物根线虫方面的作用，为进一步揭示植物抗根线虫生化和分子机理及生防新途径研究奠定基础。

Cereal cyst nematode (CCN, causal agent Heterodera avanae) has been documented as one of major restrictive factors to cereal production in China and around the world. However, few CCN resistance genes were cloned and characterized in wheat and its relatives up to date, and neither of them had confirmed function in CCN resistance. Based on generation of a root transcriptome of Ae. variabilis accession No.1 during CCN infection, the phenylalanin and isoquinoline metabolisms were deduced to have central roles in CCN resistance of Ae. variabilis No.1. By investigation of gene expression levels involved in these metabolism pathway, a cross-hub enzyme, tryptophan decarboxylase (TDC), was found to be significantly up-regulated by CCN infection. In this study, we will clone the genes encoding tryptophan decarboxylase from Ae. variabilis No.1, and characterize them by means of gene structure analysis, subcellular localization, and gene expression. Furthermore, genetic transformation approach will be utilized into tobacco, Arabidopsis thaliana, and wheat to validate its function. Meanwhile, the gene silencing will be also performed by RNAi technology. According to the secondary metabolites change, we will explore the association among the secondary metabolism, the CCN resistance and morphology of root of Ae. variabilis No.1 during the CCN infection. Overall, a critical role for phenylalanine and isoquinoline metabolism in the resistance of Ae. variabilis No.1 to the CCN, even the RKN will be elucidated via our research, which will provide new insights into the molecular mechanisms related to CCN resistance.