Park Chang-Jin, Wei Tong, Sharma Rita, Ronald Pamela C
Department of Plant Pathology and the Genome Center, University of California Davis, Davis, CA, 95616, USA.
Department of Bioresources Engineering and the Plant Engineering Research Institute, Sejong University, Seoul, 05006, Republic of Korea.
Rice (N Y). 2017 Dec;10(1):27. doi: 10.1186/s12284-017-0166-1. Epub 2017 Jun 2.
The rice immune receptor XA21 confers resistance to the bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo). To elucidate the mechanism of XA21-mediated immunity, we previously performed a yeast two-hybrid screening for XA21 interactors and identified XA21 binding protein 21 (XB21).
Here, we report that XB21 is an auxilin-like protein predicted to function in clathrin-mediated endocytosis. We demonstrate an XA21/XB21 in vivo interaction using co-immunoprecipitation in rice. Overexpression of XB21 in rice variety Kitaake and a Kitaake transgenic line expressing XA21 confers a necrotic lesion phenotype and enhances resistance to Xoo. RNA sequencing reveals that XB21 overexpression results in the differential expression of 8735 genes (4939 genes up- and 3846 genes down-regulated) (≥2-folds, FDR ≤0.01). The up-regulated genes include those predicted to be involved in 'cell death' and 'vesicle-mediated transport'.
These results indicate that XB21 plays a role in the plant immune response and in regulation of cell death. The up-regulation of genes controlling 'vesicle-mediated transport' in XB21 overexpression lines is consistent with a functional role for XB21 as an auxilin.
水稻免疫受体XA21赋予对细菌病原体水稻白叶枯病菌（Xanthomonas oryzae pv. oryzae，Xoo）的抗性。为阐明XA21介导的免疫机制，我们之前进行了酵母双杂交筛选以寻找XA21相互作用蛋白，并鉴定出XA21结合蛋白21（XB21）。
在此，我们报道XB21是一种类似辅助蛋白的蛋白，预测其在网格蛋白介导的内吞作用中发挥功能。我们利用水稻中的免疫共沉淀证明了XA21与XB21在体内的相互作用。在水稻品种 Kitaake 和表达XA21的 Kitaake转基因系中过表达XB21会赋予坏死病变表型，并增强对Xoo的抗性。RNA测序显示，XB21过表达导致8735个基因差异表达（4939个基因上调，3846个基因下调）（≥2倍，FDR≤0.01）。上调的基因包括那些预测参与“细胞死亡”和“囊泡介导的转运”的基因。
这些结果表明XB21在植物免疫反应和细胞死亡调控中发挥作用。XB21过表达系中控制“囊泡介导的转运”的基因上调与XB21作为辅助蛋白的功能作用一致。
