Submitted to: Maize Genetics Cooperation Newsletter
Publication Type: Abstract Only
Publication Acceptance Date: March 31, 1995
Publication Date: N/A
Technical Abstract: A gene (mdm1) for resistance to MDMV is located on chromosome 6S. This gene has been mapped in several inbred lines by reciprocal chromosomal translocations and linkage to molecular (umc85) or morphological (y1) markers. RFLP analyses of bulked segregates of the phenotypic classes from segregating F2 populations were used to determine if mdm1 was responsible for the resistance to MDMV found in exotic germplasm. Originally, 163 tropical inbreds were screened in the greenhouse for resistance to MDMV strains A and B by rub-inoculating them with sap from infected plants. Forty-five lines were identified as being potentially resistant. The 45 inbreds were crossed to susceptible inbreds Oh28, yM14, and K55, and F2 populations were produced. The F2 populations were then screened for their response to MDMV-A in the greenhouse. Twenty-nine inbred lines had two or more F2 populations with segregation ratios consistent with MDMV resistance being controlled by a single dominant gene. Leaf tissues from the plants exhibiting resistant and susceptible responses were collected and pooled for DNA extraction. In RFLP analyses of the bulked segregate pools, a factor linked to 6S markers was present in the resistant pools but not in the susceptible pools.