转录因子OsbHLH59通过调控木聚糖酶抑制蛋白OsXIP表达水平影响水稻抗褐飞虱的机制研究

OsbH LH59 involved in rice resistance to Nilaparvata lugens(St?l) by regulating the expression level of xylanase inhibitor protein OsXIP

木聚糖酶抑制蛋白(xylanase inhibitor protein,XIP)在植物防御中发挥作用,实验室前期研究发现,水稻木聚糖酶抑制蛋白OsXIP能响应褐飞虱[Nilaparvata lugens(St?l)]胁迫。转录因子OsbHLH59可以与OsXIP的启动子结合以响应褐飞虱侵害。本研究利用转基因技术获得OsbHLH59过表达水稻株系并利用CRISPR/Cas9系统获得了OsbHLH59突变水稻株系,研究了转录因子OsbHLH59对OsXIP表达水平的影响及其在水稻抗褐飞虱中的作用。结果表明,OsbHLH59的过表达引起了OsXIP表达水平的上调。褐飞虱侵害对OsbHLH59过表达株系和OsXIP基因表达水平高的株系的生长水平影响相较野生型更小。与野生型相比,过表达OsbHLH59和OsXIP基因均降低了褐飞虱的取食偏好。同时,OsbHLH59过表达株系和OsXIP过表达株系的防御相关基因表达水平更高,H2O2含量更低,保护性酶活性也更高。综上所述,OsbHLH59可以提高OsXIP的表达,OsXIP在水稻响应褐飞虱胁迫中发挥了重要作用。

Xylanase inhibitor protein (XIP) is considered to participate in plant defense. Os XIP was found to be a stressresponsive gene of Nilaparvata lugens (St?l) in the previous study. The transcription factor Osb HLH59 could be combined with the promoter of Os XIP in response to brown planthopper (BPH) treatment. In order to study whether Osb HLH59 was involved in regulating the expression of Os XIP and mediating rice resistance to BPH, Osb HLH59 overexpression transgenic lines were obtained by transgenic methods, and Osb HLH59 mutant lines were obtained by using CRISPR/Cas9 system. The results showed that the expression levels of xylanase inhibitor Os XIP enhanced accompanied with the increased overexpression level of transcription factor gene Osb HLH59. Through the determination of agronomic traits, it was found that the growth of Osb HLH59 overexpression lines and Os XIP overexpression lines was less affected by the BPH treatment compared with wild type (WT). When WT plants and transgenic plants were exposed to BPH, the feeding preference of BPH in Osb HLH59 overexpression and Os XIP overexpression lines reduced compared with that of WT. With the BPH treatment, higher expression levels of defense-related genes were found in Osb HLH59 overexpression and Os XIP overexpression lines. In addition, compared with WT, Osb HLH59 overexpression and Os XIP overexpression lines had stronger abilities to remove excess HOand higher antioxidant enzyme activities. This study reveals that Osb HLH59 can activate the expression of Os XIP, and Os XIP participates in rice resistance to BPH.