Abstract:

Maize rough dwarf virus (MRDV) is one of the most important diseases in maize production in China. In this study, we characterized the genetic diversity in 64 maize inbred lines in relation to MRDV. Sixty-four inbred lines were evaluated for reaction to MRDV under field conditions during 2003 and 2004 at Linfen, Shanxi Province, China. The randomized complete block design in the filed was used with 2 repetitions. The inbred lines were grown in 1-row plots, and the rows were 5 m long each and spaced 0.6 m apart with 17 holes per row and 2 seedlings per hole. At mature stage, the total number of the plants and the number of the diseased plants and the diseased plant incidence by taking the plot as a unit was calculated. Disease incidence was used to determine the response of each inbred to MRDV, which is 0 to 0.2% for high resistance, 2.1% to 5.0% for resistance, 5.1% to 10.0% for moderate resistance, 10.1% to 20.0% for susceptibility, 20.1% to 100% for high susceptibility, respectively. The disease evaluation resulted in identification of 12, 17 and 18 inbred lines offering high to moderate resistance to MRDV, besides 17 inbred lines conferring susceptibility. The diversity at the DNA level was investigated based on 70 SSR markers. The total number of alleles was 276. A mean polymorphism information content of 0.57, with a range of 0.177 to 0.825, was observed. The UPGMA analysis showed that 64 inbreds could be classified into six subgroups (Sipingtou, Luda Red Cob, PA, PB, BSSS and Lancaster), which were generally consistent to their known pedigree information and breeder’s experiences. Comprehensive differences were observed on the means of percent plants infected by MRDV among the six groups with the lowest level of 1.60% for PB and 4.95% for Sipingtou. Both groups were identified as the important sources of resistance to MRDV.

Key words: Zea mays L., Maize rough dwarf virus, Disease incidence, Genetic variation, Simple sequence repeats