水稻干尖线虫病抗性QTL的精细定位与遗传分析

Rice white tip nematode, Aphelenchoides besseyi, is a kind of foliar nematodes that often infects rice and causes "white tip" symptom, consequently leading into substantial loss of yield in most rice-growing areas of the world. In the southeast of China this nematode also causes small panicle and grains (SPGs), and greatly reduces the rice production. Resistant cultivars offer the most favorable and durable method of controlling A. besseyi in rice. Nevertheless, lack of the resistant rice cultivar allows this nematode difficult to eliminate. Our previous resistance assessment tests demonstrated that the rice cultivar Tetep exhibited a highest resistance to A. besseyi, and further efforts has been made to primary mapping resistance genes in Tetep by using marker-assisted breeding (MAS). Basing on the results, six resistance genes locus then were found in the 3, 5, 9 11 chromosome of Tetep separately. In the present study, we therefore devote to fine mapping of these QTLs conferring resistance to Aphelenchoides besseyi.We believe this ongoing research will accelerate exploration and cloning the resistance genes, and facilitate the studies on the molecular interaction mechanisms of A. besseyi and its host plants, as well as at least partially provide meaningful information of controlling the migratory plant nematodes.

水稻干尖线虫是世界广泛分布的能严重危害水稻的迁徙性寄生线虫，在我国尤其是在南方稻区该线虫已造成巨大的产量和经济损失。控制该线虫最可靠的途径是种植抗性品种，然而抗性品种的缺失导致水稻干尖线虫病害日益猖獗。本项目基于前期筛选到的高抗材料特特普，拟采用表性分析结合分子标记及作图定位等分子辅助育种的手段对特特普中的抗性基因的遗传位点进行精细定位，进而为水稻干尖抗性基因的克隆和抗性品种的选育提供理论支持。鉴于目前国内外有关迁徙性植物线虫（包括水稻干尖线虫）抗性基因的研究比较匮乏，本项目的顺利完成有助于深刻阐明水稻干尖线虫与水稻互作分子机制，并对迁徙性植物线虫的寄生规律和病害控制提供有价值的参考。

水稻干尖线虫是世界世界十大植物病原线虫之一，在全世界范围皆有分布，严重危害水稻的安全生产，在我国南方稻区因水稻干尖线虫病可造成数亿元的经济损失。控制该线虫最可靠的途径是种植抗性品种，然而抗性资源的严重匮乏导致该病害难以有效控制。本项目基于前期筛选到的高抗材料特特普和感病品种淮稻5号，利用水稻信息学数据平台发布的842对SSR标记引物对以F2后代分离群体的DNA为模板进行PCR扩增，筛选获得160对多态性SSR标记；以百粒种子带虫量（NA）、穗重损害率（LRPW）和结实损害率（LRGPP）为主要评估指标利用遗传学软件构建遗传连锁图谱，在3、5和9号染色体中共鉴定到6个抗性QTL。同时，利用RNA-seq对响应水稻干尖线虫早期侵染的水稻进行高通量测序，获得了大量差异表达基因，其中包括46个抗性反应基因，通过荧光定量PCR技术已经对其中部分基因进行了验证，并对一个新的线虫特异诱导的抗性基因（命名为Hs1PRO-1 like）进行了结构分析。本研究首次鉴定了水稻干尖线虫病抗性QTL位点，以及通过RNA-seq筛选水稻的抗性相关基因，相关研究成果为水稻干尖线虫抗性基因深入挖掘和抗病分子育种提供了理论依据，同时促进了水稻干尖线虫与水稻互作分子机制，并对水稻线虫病害的控制提供了有价值的参考。