利用重组自交系群体分析籼稻A232抗三化螟相关QTL

QTL Analysis for Resistance to Scirpophaga Incertulas Using Indica Rice A232 Recombinant Inbred Lines

水稻种质资源中抗螟虫种质较少,A232为中抗二化螟和三化螟的籼稻材料。为发掘A232抗螟性相关QTL,本研究利用以抗虫材料A232为父本与籼稻保持系岗46B(感三化螟)为母本所杂交构建的重组自交系(recombinant inbred line,RIL)F9群体为材料,2012-2013年在海南自然条件下对RIL群体中的104个株系进行三化螟抗性鉴定,利用130个在A232和岗46B表现多态性的简单重复序列(SSR)标记构建遗传连锁图谱,并同时采用复合区间作图法(CIM)和MCIM方法进行QTL分析。研究结果表明,采用复合区间作图法(CIM)共检测到7个枯心指数QTL,分布在第1、第2、第6、第10和第11染色体上。其中,q DHI-2-1的效应值最大,LOD值为3.83,位于第2染色体,两侧连锁标记为RM1358和RM35494,可解释表型变异的25.12%。q DHI-1-1、q DHI-6-1、q DHI-6-2和q DHI-10四个QTLs的加性效应负值,说明增效的抗虫等位基因来源于父本A232,具有弱化枯心指数作用,这些位点有望用于抗虫育种研究。采用MCIM方法检测到2个QTLs,位于第1和2染色体,可分别解释变异的11.68%和6.59%;在第4和第6染色体检测到1对上位QTLs,可以解释7.57%的表型变异。这些研究结果为阐明A232对螟虫抗性的遗传基础及进一步开展抗螟虫水稻育种提供依据。

Scirpophaga incertulas,a monophagous pest of paddy,is considered as one of the most destructive pest of rice.A good level of resistance against the widespread Chilo suppressalis and Scirpophaga incertulas has been rare in the rice germplasm.The indica rice A232 is moderately resistant to Chilo suppressalis and Scirpophaga incertulas.The aim of this study was to explore the resistance genes（QTLs） of A232 to the rice Scirpophaga incertulas,a recombinant inbred line（F9） population,derived from a cross between A232 and Gang46B（susceptible indica rice culture to Chilo suppressalis and Scirpophaga incertulas）.In 2012 and 2013,the level of resistance to Scirpophaga incertulas for 104 recombinant inbred lines were assessed under natural rice fields condition in Hainan province by measuring the dead-heart index（DHI）,a linkage map from this population was constructed by using 130 simple sequence repeat markers.Seven QTLs were identified by Win QTLCart2.5（CIM）,namely q DHI-1-1,q DHI-2-1,q DHI-2-2,q DHI-6-1,q DHI-6-2,q DHI-10 and q DHI-11,which were located on chromosomes 1,2,6,10 and11 respectively.Among these QTLs,q DHI-2-1,mapping in the interval between RM1358 and RM3549 on chromosome 2,it had a relative high logarithm of the odds（LOD） score and explained 25.12% of the phenotypic variation.Four QTLs,the q DHI-1-1,q DHI-6-1,q DHI-6-2 and q DHI-10,which considered to be valuble for further resistant breeding programs,because they have negative additive effects to the dead-heart index that comes from resistant parent A232.Meanwhile,using QTLNetwork-2.1（MCIM）,q DHI-1-2 and q DHI-2-3 were identified and located on chromosomes 1 and 2 respectively.The epistasis analysis indicated that a pair of QTLs（q DHI-4and q DHI-6-2） has negative epistasis effect for the dead-heart index.As the prediction of genetic effects,the study will be contributed to the understanding of the genetic basis for the resistance of rice A232 and to the future use in breeding rice,varieties with resistance to Scirpophaga incertulas.