Submitted to: Maize Genetics Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: January 31, 2005
Publication Date: March 14, 2005
Citation: Jones, M.W., Redinbaugh, M.G., Louie Jr, R. 2005. The effects of combining regions of chromosomes 3, 6 and 10 on resistance to maize dwarf mosaic virus (MDMV) and sugarcane mosaic virus-mdb (SCMV) [abstract]. Annual Maize Genetics Conference. p. 225. Technical Abstract: Genes controlling resistance to diseases caused by viruses in the family Potyviridae have mapped to maize chromosomes three, six and ten. To study the effects of the individual genes, near isogenic lines (NIL) were made that carry specific chromosomal regions from the highly resistant inbred line Pa405 in an otherwise susceptible background (inbred line Oh28). NIL W1 carries the region of chromosome 6 (bin 6.01 near umc85) that has the Mdm1, Scm1 and Wsm1 genes for resistance to MDMV, SCMV and Wheat streak mosaic virus (WSMV), respectively. NIL W2 carries a region near the centromere of chromosome three (bin 3.05 near umc102) that has the Scm2 and Wsm2 genes for resistance to SCMV and WSMV, respectively. NIL W3 carries the Wsm3 gene for WSMV resistance on chromosome 10 (bin 10.05 near umc44). Dosage effects and gene interactions were studied using intercrosses of the NIL and crosses of the NIL to the susceptible recurrent parent. All three NIL were highly resistant to WSMV, as were NIL x Oh28 hybrids. Thus, Wsm1, Wsm2 and Wsm3 each acted as single dominant genes. In contrast, W1 showed incomplete resistance to MDMV and SCMV in that limited symptoms appeared 14 and 18 days after inoculation, respectively. W1 x Oh28 hybrids were susceptible to SCMV and MDMV, but symptom development was delayed and initially limited in MDMV-inoculated plants. Neither W2 nor W3 was resistant to MDMV or SCMV. However, in W1 x W2 hybrids, MDMV and SCMV resistance was enhanced, with a lower percentage of infected plants and delayed symptom appearance relative to W1. In addition, MDMV but not SCMV resistance was enhanced in W1 x W3 hybrids. These results indicated that MDMV and SCMV resistance genes on chromosome 6 were dependent on allele dosage, and were affected by the addition of minor genes.