Bph36介导的抗性机制及相关信号通路的研究

褐飞虱（Nilaparvata lugens Stål., BPH）是水稻最主要的害虫之一,给水稻生产造成严重的危害。携带不同抗性基因的抗褐飞虱水稻材料抗性机制不同,挖掘普通野生稻抗褐飞虱基因并研究其介导的抗性机制及相关信号通路对水稻育种具有重要的意义。本研究基于课题组前期从广西普通野生稻‘W2183'挖掘出的位于4号染色体InDel标记S13和X48之间38 kb处新基因Bph36,以‘9311'和‘抗蚊青占'为感性对照,05RBPH16和NIL-Bph36为抗性对照,通过褐飞虱宿主选择性、蜜露量测定、褐飞虱存活率及褐飞虱生长速率等方法分析Bph36介导的抗褐飞虱机制;同时,以‘抗蚊青占'为感性对照,NIL-Bph36为抗性对照,通过qRT-PCR分析植物防御昆虫侵害的三大信号途径：水杨酸、茉莉酸和乙烯相关基因表达量的差异。抗性机制研究结果表明：褐飞虱在抗性材料植株上的虫口密度显著低于感性材料植株,抗性材料上的褐飞虱存活率、群体生长率及取食后排泄的蜜露量均比感性对照显著降低。Bph36介导的抗性机制是寄主抗生性和害虫趋避性相互作用的结果。qRT-PCR结果表明：褐飞虱取食后,各个时间段抗性材料NIL-Bph36植株中水杨酸合成相关基因EDS1、PAD4、PAL和水杨酸途径病程相关蛋白基因PR10的表达量显著高于感性材料‘抗蚊青占'植株中的表达量;抗性材料NIL-Bph36植株中,茉莉酸合成基因LOX2和茉莉酸积累基因AOS2的表达量比褐飞虱取食前显著提升,但是比同时段感性材料植株中表达量显著降低;褐飞虱取食后,抗、感性材料植株中乙烯信号途径基因EIN2的表达量都受到抑制,基因ACO3表达量都提高,但2种材料间的差异不显著。茉莉酸途径和乙烯途径参与了NIL-Bph36植株抗褐飞虱的基础防御反应,但Bph36激活的抗性不是茉莉酸和乙烯依赖的信号防御途径而是激活水杨酸依赖的系统获得性抗性。研究结果为进一步研究Bph36与其他抗性基因聚合,培育兼有多种抗性机制和防御信号途径的优良品种奠定基础。

Bph36-mediated Resistance Mechanism and Related Signal Pathways

Brown planthopper (Nilaparvata lugens Stål., BPH) is one of the most important pests of rice, which causes serious harm to rice production. The mechanisms of brown planthopper resistant genes in rice materials are different. It is of great significance for rice breeding to explore the resistance mechanism and related signal pathway of brown planthopper resistant genes in common wild rice. This work investigated the new BPH resistance gene Bph36 flanked by InDel markers S13 and X48 on the short arm of rice chromosome 4 derived from Guangxi common wild rice ‘W2183'. The mechanism of Bph36-mediated resistance to brown planthopper was analyzed by host selection, honeydew quantity measurement, survival rate and growth rate of brown planthopper based on the susceptible control, 9311 and ‘Kangwenqingzhan', and resistant control, 05RBPH16 and NIL-Bph36. qRT-PCR was used to analyze the expression level of defence-related genes of salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) pathways of plant defense against insect invasion based on susceptible control ‘Kangwenqingzhan', and resistant control NIL-Bph36. The results showed that the population density of the brown planthopper on the resistant material was significantly lower than that on the sensitive material, and the survival rate, population growth rate, and honeydew excreted by the brown planthopper on the resistant material were significantly lower than that on the susceptible control. Bph36 mediated resistance was the result of the interaction between host resistance and pest avoidance. qRT-PCR revealed in response to brown planthopper feeding, the expression level of SA synthesis-related genes, EDS1, PAD4, PAL and SA defense-related gene PR10 in NIL-Bph36 was significantly higher than that in ‘Kangwenqingzhan', and the expression level of JA synthesis-related gene LOX2 and JA accumulation-related gene AOS2 in NIL-Bph36 was significantly increased in comparison to that before feeding, but significantly decreased in comparison to that in susceptible plants. The expression of ET signaling pathway gene EIN2 and ACO3 was inhibited and increased, respectively, in both resistant and susceptible materials in response to brown planthopper feeding, but there was no significant difference between the two materials. JA/ET pathways were involved in the basic defense response of NIL-Bph36 against brown planthopper, but the BPH resistance gene Bph36 acquired resistance via SA-dependent activation pathway and JA/ET- -independent activation pathway. The results would lay a foundation in a breeding program for rice quality with multiple resistance mechanisms and defense signaling pathways from the aggregation of the BPH resistance gene Bph36 with other resistance genes.