水稻恢复系华占抗稻瘟病遗传分析及基因鉴定

 华占是近年来我国新选育的恢复系,广泛应用于杂交稻育种中,其配组的杂交稻组合对稻瘟病均表现出良好的抗性。本研究利用来源于华南稻区的62个稻瘟病菌株对恢复系华占、明恢63和广恢998进行抗病性鉴定,结果表明:华占对接种菌株的抗谱达到95.2%,对稻瘟病表现出广谱抗性。为进一步了解该恢复系所含的抗稻瘟病基因,以高感稻瘟病品种丽江新团黑谷为母本,以华占为父本,构建了丽江新团黑谷(LTH)/华占的F₂抗病遗传分析群体。利用对华南水稻品种具有致病谱较广的稻瘟病代表菌株GD00-193a对随机选择的1 000个来源于LTH/华占的F₂个体及其F₁个体进行抗病遗传分析,结果发现F₁个体表型全为抗病,1 000个F₂个体的抗/感比率符合3∶1的显性单基因分离比,说明华占至少含有一个显性抗稻瘟病基因。利用均匀分布于水稻12条染色体的250对SSR引物,通过分离群体分析结合隐性群体分析法将华占的一个抗稻瘟病基因定位于水稻第6染色体的Pi2/Pi9/Pi50区域。通过Pi2等位基因的测序分析,结果表明华占含有Pi2抗病基因。本试验结果为华占在杂交稻上的应用及其配组组合的品种布局提供重要依据。

Genetic analysis and gene identification of restorer line Huazhan against rice blast

Huazhan is a new native restorer line bred in China and widely used in recent years. Its hybrid rice combinations showed good resistance against rice blast. In the present study, 62 blast isolates collected from South China were used for inoculating the restorer lines of Huazhan, Minghui63 and Guanghui998. The inoculation tests revealed that Huazhan was a broad resistant restorer line whose resistance spectrum (RS) was 95.2%. To identify the rice blast resistance gene(s) of Huazhan,we constructed a F₂ population derived from Lijiangxintuanheigu (LTH, as a female parent) and Huazhan (as a male parent) for genetic analysis. The blast isolate GD00-193a which had a broad virulence to rice cultivars from South China was used to inoculate all of the F₁ and 1 000 F₂ individuals of LTH/Huazhan. The genetic assay indicated that Huazhan carried a dominant resis-tance gene, since all of the F₁ plants were resistant and the segregation of resistant and susceptible progenies fitted a 3R∶1S ratio in the F₂ population. The resistance gene was mapped in the Pi2/Pi9/Pi50 region on chromosome 6 through bulked segregant analysis (BSA) and recessive class analysis (RCA) using 300 microsatellite markers equally distributed on 12 rice chromosomes. The result of further Pi2 alleles sequencing showed that Huazhan carried the Pi2 gene. The present study will provide the basis for the application of Huazhan in hybrid rice breeding and the variety distribution and rotation of its combinations.