Isozyme parameters in genetic evaluation in Brassica - a tribute to Haldane's vision on the synergy between biochemistry and genetics

Abstract

Isozymes as biochemical markers possess distinct advantages over molecular markers like RFLP in breeding for quantitative trait (QT) improvement. Five parameters exhaustive of isozyme variation, viz. number of bands, relative absorption, standard error (relative absorption), relative mobility, and standard error (relative mobility) (IST) were conceived. The two standard error parameters are new and not used so far. They are crucial in accounting for environmental contributions to isozyme variation. In this paper, varieties were arranged into a set of base groups on a genetic basis using six QTs. The grouping was done afresh on IST and a commonality index was used to measure the efficiency of IST in genetic differentiation. Using two sets of experiments in Brassica representing four species, and the enzyme esterase, it was shown that IST based on esterase alone was quite efficient in identifying the base genetic groups. The results confirm Prof. J.B.S. Haldane's vision that integration of biochemical and genetic concepts on properly designed experiments, logically conceived data and analysis will provide novel avenues for innovative methods of improvement.