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Abstract

New plant type wheat lines have been developed at the Indian Agricultural Research Institute, New Delhi, by combining some of the negatively correlated yield con- tributing traits such as more grains per panicle, lar- ger grain size and optimum tillers per plant through inter-varietal hybridization followed by a modified- bulk pedigree method of selection. Some of these lines have been found to give 15–22% higher yield in ex- perimental plots than the most popular national check varieties being cultivated in the north-western part of India and thus constitute a valuable source of genetic variation for breaking yield barriers in wheat. With the objective of precise differentiation and identifica- tion of new plant type wheat lines, 33 sequence tagged microsatellite site markers, which are genetically located on different chromosomes of wheat genome, were employed. These markers in combination differ- entiated the new lines from 137 wheat varieties released for commercial cultivation in India. Fourteen markers detected polymorphism among the thirteen genotypes included in this study, of which eight mark- ers in combination differentiated the seven new wheat lines from each other as well as from their parents. Inheritance of parent-specific alleles revealed the direction of selection during breeding. Grouping of the lines based on cluster analysis reflected the nature of their relationship with the parent varieties. A graphic presentation of the genetic constitution of the new plant type lines was developed, which can be used as bar-coded molecular tags for identification of the respective seed samples.