Identification And Mapping Of A New Gene For Resistance To Maize Dwarf Mosaic Virus In Maize

Maize dwarf mosaic virus (MDMV) is one of the most widespread viral diseases of maize in the world. In this study, a major gene conditioning the resistance to MDMV strain B in the resistant inbred line Huangzaosi derived from Tangsipingtou was found by the joint analysis based on parents, F,, F2 and backcrosses. It was reported to identify the new recessive gene for resistance to MDMV strain B in Huangzaosi by the allelism test. Furthermore, the new resistance gene was located and mapped using chromosome translocations and microsatellite markers, respectively. The results were as follows:1. The inheritance of resistance to MDMV strain B in the resistant inbred line Huangzaosi derived from Tangsipingtou was studied by the major-polygene mixed inheritance models based on parents, F,, F2 and backcrosses from Huangzaosi x Mo 17 ^ Huangzaosi x 8112 and Huangzaosi x Ye 107. One major gene for resistance to MDMV was identified in Huangzaosi at adult stage.2. The allelism test was used to identify the new recessive gene for resistance to MDMV in Huangzaosi, which was different from the resistance gene Mdml in Pa405. We proposed to designate this gene as mdml (t) temporarily.3. The chromosome mapping showed that mdml (t) was located on the long arm of chromosome 6, near the centromere. The linkage distances between mdml (t), Mdml, and the breakpoint of the translocation, T6-9b, are 1.9-4.5 cM and 33.8 cM respectively.4. Bulked segregate analysis and microsatellite analysis of the F2 populationfrom the cross Huangzaosi x Mol 7 were employed to map the recessive resistance gene, mdml (t), on the long arm of chromosome 6. The new resistance gene mdml (t) was tightly linked to and located between the microsatellite marker loci, phi077 and bnlg391, which were screened out by 27 pairs of microsatellite markers. The linkage distances between phi077 - mdml (t)/mdml (t) -bnlg391 are 4.74cM and 6.72cM for the first and the second intervals respectively. Meanwhile, the studies on the inheritance of resistance to MDMV and the chromosomal location of the resistance gene were confirmed.The identification and mapping of the new resistance gene mdml (t) inHuangzaosi will facilitate the selection for the resistant genotypes in breedingprograms and provide the basis for map based cloning of the new resistancegene.