Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/1997
Publication Date: N/A
Citation: N/A Interpretive Summary: Genetic mapping of the chickpea genome is difficult because available genetic marker systems do not identify a sufficient number of polymorphisms in chickpea for efficient mapping. In this study, we used a new marker system know as inter-simple-sequence-repeat, or ISSRs, which was expected to be more efficient when compared to other available methods. The study showed that the procedure was efficient in identifying a sufficient number of polymorphisms for use in mapping of the chickpea genome. Furthermore, markers were identified that were linked to a gene for resistance to fusarium wilt, an important disease of the crop. The close linkage of the ISSR marker to the gene makes it possible to use marker assisted selection in germplasm improvement programs. This is the first report of an ISSR marker linked to an important disease resistance gene in any crop.
Technical Abstract: The inheritance of an inter-simple-sequence-repeat (ISSR) polymorphism was studied in a cross of cultivated chickpea (Cicer arietinum L.) and a closely related wild species (C. reticulatum Lad.) using primers that anneal to a simple repeat of various lengths, sequences and non-repetitive motifs. Dinucleotides were the majority of those tested, and provided all of the useful banding patterns. The ISSR loci showed virtually complete agreement with expected Mendelian ratios. Twenty two primers were used for analysis and yielded a total of 31 segregating loci. Primers based on (GA)n repeats were the most abundant while primers with a (TG)n repeat gave the largest number of polymorphic loci. Nucleotides at the 5' and 3' end of the primers played an important role in detecting polymorphism. All the markers showed dominance. We found an ISSR marker linked to the gene for resistance to fusarium wilt race 4. The marker concerned, UBC-855 500, was sfound to be linked in repulsion with the fusarium wilt resistance gene at distance of 5.2 cM. It co-segregated with CS-27 700, a RAPD marker previously shown to be linked to the gene for resistance to fusarium wilt race 1, and was mapped to linkage group 6 of the Cicer genome. This indicated that genes for resistance to fusarium wilt races 1 and 4 are closely linked. The marker UBC-855 500 is located 0.6 cM from CS-27 700 and is present on the same side of the wilt resistance gene. To our knowledge this is the first report of the utility of an ISSR marker in gene tagging. These markers may provide valuable information for the development of sequence-tagged microsatellite sites (STMS) at a desired locus.