Genetic mapping of the Isaac-CACTA transposon in maize.

We constructed a genetic linkage map with Isaac-TD, SSR, and SNAP markers in a RIL population which had been derived from a cross of waxy corn (KW7) and dent corn (Mo17). A total of 368 markers, including 241 Isaac-TD, 121 SSR, and 6 SNAP markers, were assigned to 10 linkage groups, encompassing 1687.0 cM, with an average genetic distance of 4.6 cM between markers. SSR markers were utilized as chromosome anchors, in order to assign the Isaac-TD markers to the chromosomes, and the number of markers in each of the linkage groups ranged between 22 and 49. The majority of the Isaac-TD markers were determined to have been distributed throughout the ten maize chromosomes. In linkage analysis of the Isaac-TD markers with genes of agronomic interest, six genes related with maize kernel starch biosynthesis, ae1, bt2, sh1, sh2, su1, and wx1, were analyzed and shown that they were closely linked with either the Isaac-TD or SSR markers on chromosomes of 3, 4, 5, and 9. We observed and mapped segregation-distorted markers on chromosomes 1, 5, 6, 7, 8, and 10, where these markers were clustered. The Isaac-TD or SSR markers which were closely linked with starch synthesis genes may prove useful in marker-assisted breeding programs.