Plant, Animal & Microbe Genomes X Conference Plant, Animal & Microbe Genomes X ConferenceJanuary 12-16, 2002
Town & Country Convention Center
San Diego, CA
Poster: Maize, Sorghum, Sugarcane, and related
SCMV resistance in maize was employed to evaluate the use of resistance gene analogues (RGAs) for plant breeding purposes in maize. Three previously published RGAs were mapped in relation to SCMV resistance genes (R genes) Scmv1 and Scmv2 on chromosomes 6S and 3L. After development of CAPS markers, mapping, and pedigree analysis of resistant inbred lines, two of them, pic19 and pic13, were confirmed to be candidates for Scmv1 and Scmv2. Pairwise sequence alignments among six inbreds revealed a frequency of one single nucleotide polymorphism (SNP) per 33 bp for the three RGAs, indicating a high degree of polymorphism and a high probability of success in converting RGAs into codominant cleaved amplified polymorphic sequence (CAPS) markers compared to other sequences. Screening of a BAC library with Scmv1 candidate pic19 revealed the existence of five BAC groups containing pic19 homologous sequences. The five groups exhibit a very high sequence identity of 94-97% on the nucleotide level, thus indicating them being duplicated members of the same gene family. Three of these groups clustered in the Scmv1 target region on chromosome 6S, two of them mapped to chromosome 1 known to contain an additional SCMV resistance QTL. Consequently, the RGA approach for the isolation of disease R genes is, besides the development of codominant CAPS markers, an efficient tool for the detection of candidate sequences at least linked to target resistance genes.