Cluster Analysis Of Maize Germplasm On The Resistance To Maize Rough Dwarf Virus And The Development Of STS-PCR Markers

Maize is the most important crops in China, and maize rough darwf disease (MRDD) is one of the most devastating diseases limiting yeild production annually. Developing and culticating resistanct hybrids is an effective approach to control the disease, while breeding efforts for resistance rely largely on good understanding of the genetic mechanism. This paper summarized the damage to corn, epidemic characteristics, virulence factors of Maize Rought Darwf Virus, and prevention methods were also discussed. Using the hereditary resistance of maize germplasm resources to selection resistant varieties is the basic way. Functional markers and QTL fine mapping would be valuable in maize disease genetic improvement.(1)Ninety-two maize inbred lines were screened by natural infection in open field and 29 were found with high resistance to Maize Rough Dwarf Virus.(2)The UPGMA analysis classified 92 inbred lines into 4 clusters, which corresponed to the heterotic groups determined by their pedigree information (P group,Sipingtou,Reid,Lancaster). Resistance identification combined with major heterotic groups showed that the most of the resistant materials are from P group, and resistant materials of Reid group are all from American. No materials were found with high resistance in Lancaster group. Efforts should be made in the development of resistant varieties using resistant germplasm in the Reid group.(3)Previous studies showed that RAPD markers S37 and S86 were co-segregated with MRDV resistance. S86 amplified a major PCR product of 1300bp in size from susceptible line 478 and this specific product was absent from resistant lines Q319,P138 and H21. S37 amplified a major fragment of 2000bp in size from resistant lines and showed polymorphic from that amplified from susceptible line 478. We isolated and sequenced both the 1300bp and 2000bp DNA fragments and converted S37 and S86 into STS-PCR markers. The converted STS markers showed the same results as those of S37 and S86,but much stable and easy to use . (4)These STS markers were further tested on 20 susceptible and 34 resistant lines.The Chi-Square test indicated the converted STS-PCR markers were significantly correlated with MRDV resistance. These stable and repeatable STS markers are of great interests to markers-assisted maize MRDV resistant variety development.