Plant & Animal Genome VI Conference

W94

AFLP ANALYSIS REVEALS EXTENSIVE CO-ADAPTIVE GENE COMPLEXES IN RICE LANDRACES

1. School of Biological Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
2. Genetic Resources Center, International Rice Research Institute, P O Box 933, 1099 Manila, The Philippines

One hundred and twenty two AFLP markers were mapped using an IR64 x Azucena doubled haploid population. The distribution of these mapped markers was monitored across a set of 48 very diverse landraces of rice. Strong statistical associations were observed between 960 of the 7,381 possible pairs of markers. These strongly associated pairs of markers mapped to the same chromosome in only 111 cases. The remaining 849 pairs were due to association between markers found on different chromosomes. All of these genetically unlinked but strongly associated markers were not randomly distributed across the genome but occupy blocks of DNA within the rice chromosomes. Within these blocks, there has clearly been maintenance of combinations of marker alleles across very diverse germplasm. This maintenance of combinations of alleles at loci on different chromosomes is expected to extend to QTL. This is because we have previously been able, using diverse germplasm, to identify statistical associations between markers and QTL and to accurately predict performance for quantitative traits across such diverse germplasm using marker data (Heredity 76, 296; 1996). We propose that our data provide strong evidence for the co-adaptation of geographically distinct landraces and that this has resulted over time in the maintenance of "adaptive gene complexes" involving important quantitative traits.