Mapping New Genetic Markers Associated with CMD Resistance in Cassava (Manihot esculenta Crantz) Using Simple Sequence Repeat Markers

Cassava mosaic disease (CMD) is the most serious disease in cassava–in India where it is grown for food, starch and sago purpose. The disease is best kept under control by exploiting the available host plant resistance, which was introgressed from M. glaziovii to cassava and it is known to be polygenic control. In the present study, an attempt was made to construct the genetic linkage map of cassava using SSR markers with the objective of mapping genes associated with CMD. Using single marker analysis (SMA), four CMD resistance markers were detected viz. SSRY28, SSRY235, SSRY44 and NS136. SSRY28 and SSRY235 were located on linkage group G and SSRY44 and NS136 on linkage group P of cassava genetic map developed by Fregene et al. (1997). Among the four markers, three (SSRY235, SSRY44 and NS136) are new markers associated with CMD resistance. The detection of markers SSRY44 and NS136 having association with CMD resistance is a new report indicating the possibility of having another genetic loci for CMD resistance in cassava in addition to the already established on linkage group G. This finding supports the polygenic control of CMD resistance.