Biosciences Eastern and Central Africa - International Livestock Research Institute (BecA-ILRI) Hub, 00100 Nairobi, Kenya.
Institute for Research Initiatives, Division for Research Strategy, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.
Plant Physiol. 2019 Apr;179(4):1796-1809. doi: 10.1104/pp.18.01133. Epub 2019 Jan 22.
species are parasitic weeds that seriously constrain the productivity of food staples, including cereals and legumes, in Sub-Saharan Africa and Asia. In eastern and central Africa, spp. infest as much as 40 million hectares of smallholder farmland causing total crop failure during severe infestation. As the molecular mechanisms underlying resistance are yet to be elucidated, we undertook a comparative metabolome study using the -resistant rice () cultivar 'Nipponbare' and the susceptible cultivar 'Koshihikari'. We found that a number of metabolites accumulated preferentially in the -resistant cultivar upon infection. Most apparent was increased deposition of lignin, a phenylpropanoid polymer mainly composed of -hydroxyphenyl (H), guaiacyl (G), and syringyl (S) aromatic units, around the site of interaction in Nipponbare. The increased deposition of lignin was accompanied by induction of the expression of corresponding enzyme-encoding genes in the phenylpropanoid pathway. In addition, perturbing normal lignin composition by knocking down or overexpressing the genes that regulate lignin composition, i.e. -COUMARATE 3-HYDROXYLASE or FERULATE 5-HYDROXYLASE, enhanced susceptibility of Nipponbare to infection. These results demonstrate that enhanced lignin deposition and maintenance of the structural integrity of lignin polymers deposited at the infection site are crucial for postattachment resistance against .
物种是寄生性杂草，严重限制了撒哈拉以南非洲和亚洲的粮食作物（包括谷物和豆类）的生产力。在东非和中非， spp. 寄生多达 4000 万公顷的小农耕地，在严重寄生时会导致作物全部歉收。由于尚未阐明抗性的分子机制，我们使用抗 的水稻（）品种“Nipponbare”和易感品种“Koshihikari”进行了比较代谢组学研究。我们发现，在 感染后，一些代谢物在抗 品种中优先积累。最明显的是木质素的沉积增加，木质素是一种苯丙烷聚合物，主要由 - 羟基苯基（H）、愈创木基（G）和丁香基（S）芳香单元组成，主要在 Nipponbare 的相互作用部位沉积。木质素的沉积增加伴随着苯丙烷途径中相应酶编码基因的表达诱导。此外，通过敲低或过表达调节木质素组成的基因，即 - 香豆酸 3-羟化酶或阿魏酸 5-羟化酶，扰乱正常木质素组成，增强了 Nipponbare 对 的易感性。这些结果表明，增强木质素沉积和维持沉积在感染部位的木质素聚合物的结构完整性对于附着后抵抗 至关重要。
