A 610 KB YAC CLONE HARBORS 7 CM OF TOMATO (LYCOPERSICON-ESCULENTUM) DNA THAT INCLUDES THE MALE-STERILE-14 GENE AND A HOTSPOT FOR RECOMBINATION

Pollen development requires both sporophytic and gametophytic gene exp ression. We are using a map-based cloning technique to isolate sporoph ytic genes which, when mutant, cause pollen abortion and a male steril e (ms) phenotype in tomato (Lycopersicon esculentum). We have genetica lly characterized one ms locus (ms14) using RFLP analysis and identifi ed flanking markers. High-resolution genomic physical mapping indicate s that the ms14 locus is located in a similar to 300 kb region. We hav e identified a YAC clone with an insert size of similar to 610 kb that contains the ms14-linked markers, reflects the organization of the ph ysical map and therefore most probably contains the ms14 gene. In addi tion, we present evidence that the relationship between physical and g enetic distance in this chromosomal region changes abruptly from simil ar to 105-140 kb/cM to less than 24kb/cM, and suggest that the TG393-T G104 region is a hotspot for recombination.