Mapping Of QTL For Resistance To Maize Rough Dwarf Disease Using Near-Isogenic Lines And Their Application In Molecular Marker-Assisted Selection

The maize rough dwarf disease （MRDD）, widespread in the world and caused greatlosses in grain yield, was a viral disease, whose pathogen had been identified as riceblack-streaked dwarf virus in China and was transmitted by the insect vector Laodelphaxstriatellus in a persistent manner. In order to control the prevalent of deseases and reducecrop losses, using resistance genes of maize to disease resistance breeding programs was aneffective way to resolve the problem radically. Marker-assisted selection （MAS） may greatlyincrease the efficiency in plant breeding for resistance to MRDV compared to conventionalbreeding. In this study, mapping quantitative trait locus （QTLs） of resistance to MRDD werestudied using two segregation populations from the two crosses of NT401/NT399andNT409/NT411. Reactions of two segregation populations to MRDD were investigated bynatural infection method in three different environments, and scored by the incidence ofMRDD. Through marker-assisted selection of feasibility analysis to four segregationpopulations, these work laid a preliminary foundation for the cloning the maize rough dwarfdisease resistant gene and the molecular marker-assisted breeding. The mainly results were asfollows:1. Mapping quantitative trait locus （QTLs） of resistance to MRDD were studied usingNT401³/NT399and （NT409²/NT411） F₁segregation populations from the two crosses ofNT401/NT399and NT409/NT411. Reactions of two segregation populations to MRDD wereinvestigated by natural infection method in three different environments, and scored by theincidence of MRDD. Based on inclusive composite interval mapping （ICIM） method, weidentified three QTLs for resistance to MRDD using （NT409²/NT411） F₁on chromosome8,but we didn’t detected any QTL by using NT401³/NT399. The contributions of the threeQTLs to the total variation were41.37%,20.51%and36.04%with LOD scores being24.03,10.29and17.02, respectively. Two QTLs were mapped to a15.47cM region between theSSR markers phi121and UMC1817, and with physical distance being92Mb in Tai’an Mayand Jining May. Another one was mapped to a0.86cM region between the SSR markers M6 and M24, and with physical distance being17.9Kb in Tai’an June.2. Through marker-assisted selection of feasibility analysis to （Chang7-2/1145）F₂、（Qi319⁶/Chun9）F₁、（Chang7-2³/CL313）F₅and （Shen137/NT396）F₈segregation populationsindicated that these major QTLs were significantly correlated with resistance to MRDD, thesemarker in the CL313,1145, Shen137and other genealogical sources of the same or similarinbred lines could be used for marker-assisted selection for resistance to MRDD in breedingprogram.