Agrama H A, Moussa M E, Naser M E, Tarek M A, Ibrahim A H
Applied Molecular Genetics Laboratory, Agricultural Research Center, Memphis 42, Alexandria 21321, Egypt, EG.
Theor Appl Genet. 1999 Aug;99(3-4):519-23. doi: 10.1007/s001220051265.
Quantitative trait loci (QTLs) of maize involved in mediating resistance to Peronosclerospora sorghi, the causative agent of sorghum downy mildew (SDM), were detected in a population of recombinant inbred lines (RILs) derived from the Zea mays L. cross between resistant (G62) and susceptible (G58) inbred lines. Field tests of 94 RILs were conducted over two growing seasons using artificial inoculation. Heritability of the disease reaction was high (around 70%). The mapping population of the RILs was also scored for restriction fragment length polymorphic (RFLP) markers. One hundred and six polymorphic RFLP markers were assigned to ten chromosomes covering 1648 cM. Three QTLs were detected that significantly affected resistance to SDM combined across seasons. Two of these mapped quite close together on chromosome 1, while the third one was on chromosome 9. The percentage of phenotypic variance explained by each QTL ranged from 12.4% to 23.8%. Collectively, the three QTLs identified in this study explained 53.6% of the phenotypic variation in susceptibility to the infection. The three resistant QTLs appeared to have additive effects. Increased susceptibility was contributed by the alleles of the susceptible parent. The detection of more than one QTL supports the hypothesis that several qualitative and quantitative genes control resistance to P. sorghi.
在由抗性自交系（G62）和感病自交系（G58）杂交得到的玉米重组自交系群体中，检测到了参与介导玉米对高粱霜霉病（SDM）病原菌高粱生指梗霉抗性的数量性状位点（QTL）。在两个生长季节对94个重组自交系进行了人工接种的田间试验。病害反应的遗传力较高（约70%）。还对重组自交系的作图群体进行了限制性片段长度多态性（RFLP）标记评分。106个多态性RFLP标记被定位到10条染色体上，覆盖1648厘摩。检测到3个显著影响跨季节对高粱霜霉病抗性的QTL。其中2个在第1染色体上紧密连锁，另一个在第9染色体上。每个QTL解释的表型变异百分比在12.4%至23.8%之间。本研究中鉴定的这3个QTL共同解释了对该病害易感性表型变异的53.6%。这3个抗性QTL似乎具有加性效应。感病亲本的等位基因导致易感性增加。多个QTL的检测支持了几个质量和数量基因控制对高粱生指梗霉抗性的假说。
