|BENKO ISEPPON, ANA-MARIA|
Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2000
Publication Date: N/A
Interpretive Summary: Chickpea is the third most important legume food crop in the world and is especially important in the developing countries of the Middle East and South Asia. It is also an important and high valued crop in the U.S. and is grown extensively in the western states of California, Washington, Idaho, Oregon and Montana. Diseases threaten the viability of the crop in all areas. Because of that threat we have identified resistance genes and have begun to map those genes in the chickpea genome. Genes for resistance to the most devastating diseases of the crop have been found and have been used in breeding. However, the mode of action and the locations of the genes in the chickpea genome has not been known until now. In this research we established a genetic mapping population and mapped the genes for fusarium wilt of chickpea. The resistant genes were mapped in the genome in relation to easily determined molecular markers. Those markers can now be used for indirect selection for the resistance genes. This information will allow breeders and geneticists to use marker assisted selection to transfer the resistance genes to otherwise susceptible germplasm material and to accelerate conventional breeding and make resistant varieties available to producers in a shorter period of time.
Technical Abstract: An integrated molecular marker map of the chickpea genome was established using 130 recombinant inbred lines from a wide cross between a cultivar resistant to fusarium wilt caused by Fusarium oxysporum Schlecht, emend. Snyd. & Hans f. Sp. ciceri (Padwick) Snyd & Hans, and an accession of Cicer reticulatum (PI 489777), the wild progenitor of chickpea. A total of 354 markers were mapped on the RILs including 118 STMS, 96 DAF, 70 AFLP, 37 ISSR, 17 RAPD, 8 isozymes, 3 cDNAs, 2 SCARs and 3 loci that confer reistance against different races of fusarium wilt. At a LOD-score of 4.0, 303 markers cover 2077.9 cM in 8 large and 8 small linkage groups at an average distance of 6.8 cM between markers. Fifty-one markers (14.4%) were unlinked. Clustering of markers in central regions of linkage groups was observed. Markers of the same class except ISSR and RAPD markers tended to generate subclusters. Also, genes for resistance to races 4 and 5 of fusarium wilt map to the same linkage group that include an STMS and a SCA marker previously shown to be linked to fusarium wilt race 1, indicating a clustering of several fusarium wilt resistance genes around this locus. Significant deviation from the expected 1 : 1 segregation ratio was ovserved for 136 markers (38.4 %, P<0.05). Segregation was biased towards the wild progenitor in 68% of the cases. Segregation distortion was similar for all marker types except ISSR's that showed only 28.5% aberrrant segregation. The map is the most extended genetic map of chickpea currently available. It might serve as a basis for marker-assisted selection and map-based cloning of fusarium wilt resistance genes and other agronomically important genes in future.