A linkage map of the chickpea (Cicer arietinum L.) genome based on recombinant inbred lines from a C-arietinumxC-reticulatum cross: localization of resistance genes for fusarium wilt races 4 and 5

An integrated molecular marker map of the chickpea genome was established u sing 130 recombinant inbred Lines from a wide cross between a cultivar resi stant to fusarium wilt caused by Fusarium oxysporum Schlecht. emend. Snyd. &. Hans f. sp. ciceri (Padwick) Snyd gr Hans, and an accession of Cicer ret iculatum (PI 489777), the wild progenitor of chickpea. A total of 354 marke rs were mapped on the RILs including 118 STMSs, 96 DAFs, 70 AFLPs, 37 ISSRs , 17 RAPDs, eight isozymes, three cDNAs, two SCARs and three loci that conf er resistance against different races of fusarium wilt. At a LOD-score of 4 .0, 303 markers cover 2077.9 cM in eight large and eight small linkage grou ps at an average distance of 6.8 cM between markers. Fifty one markers (14. 4%) were unlinked. A clustering of markers in central regions of linkage gr oups was observed. Markers of the same class, except for ISSR and RAPD mark ers, tended to generate subclusters. Also, genes for resistance to races 4 and 5 of fusarium wilt map to the same linkage group that includes an STMS and a SCAR marker previously shown to be linked to fusarium wilt race 1, in dicating a clustering of several fusarium-wilt resistance genes around this locus. Significant deviation from the expected 1 : 1 segregation ratio was observed for 136 markers (38.4%, P<0.05). Segregation was biased towards t he wild progenitor in 68% of the cases. Segregation distortion was similar for all marker types except for ISSRs that showed only 28.5% aberrant segre gation. The map is the most extended genetic map of chickpea currently avai lable. It may serve as a basis for marker-assisted selection and map-based cloning of fusarium wilt resistance genes and other agronomically important genes in future.