SUMMARY Charcoal rot [Macrophomina phaseolina (Tassi)

Goid.] causes significant yield losses to common bean (Phaseolus vulgaris L.) in Mexico when drought and high temperature stress occur. In this work, in vitro reac-tions to M. phaseolina in the cotyledons of 100 F2 plants derived from the cross BAT 477 (resistant) x Pinto UI-114 (susceptible) and the parents were measured, and AFLP molecular markers associated with BAT 477 M. phaseolina resistance were found. The AFLP analysis consisted of selective amplification using 20 EcoRI + 3/MseI + 3 selective oligonucleotides. Charcoal rot re-sistance is controlled by two dominant genes with dou-ble recessive epistatic effects. AFLP analysis produced 294 polymorphic amplified products. Using the 130 least distorted loci a linkage map was produced that included eight LG where 30 loci were mapped. A possible quanti-tative trait locus (QTL) was found at linkage group 1 (LG1) showing logarithm of odds (LOD) = 5.11 (critical LOD for genomic amplitude level = 7.23 and critical LOD for chromosomal amplitude = 5.5 based on per-mutation tests). A permutation test for single markers by regression analysis produced a critical value F = 14.76. However, the locus with the highest F was ATA/AGT-19 (F = 9.329, P = 0.0029). In conclusion, BAT 477 resist-ance to charcoal rot was controlled by two dominant genes with double-recessive epistasis and one possible QTL at LG1 was detected in BAT 477. Better under-standing of charcoal rot resistance will provide improved protection for common beans in the future