Construction of a genetic linkage map and mapping of drought tolerance trait in Indian beveragial tea

Tea is an important health drink which contributes significantly to the economy of Asian and African countries. India contributes about 29 % of the world's total tea production where majority of the tea cultivated is Assam type (native to Assam, India). Apart from India, Assam type contributes to the majority of tea grown in tropical regions of Sri Lanka and Kenya as well. We have developed the first genetic linkage map in Indian beveragial tea using 234 DNA markers (AFLP and RAPD). The plausibility of the linkage group formation was compared using two-way pseudo-testcross approach (using maximum likelihood algorithm) and integrated approaches (using regression algorithm). Both the approaches generated linkage maps containing 18 linkage groups. The composition and order of markers in the corresponding linkage groups in both the maps showed significant congruence. Maximum likelihood algorithm could map 78.6 % of the markers with total map length of 8527.5 and 45.3 cM average distance between each marker. Regression algorithm could map 73.5 % of the total markers with total map length of 2051.7 and 14.96 cM average distance between each marker. Drought is the major abiotic stress responsible for heavy yield losses in cultivated tea all over the world. The present map was used to map the locus, AFLP_CS_87 that segregates with drought tolerance phenotype in both the maps.