Uttar Pradesh Agriculture Department, Kanpur
A semi-dominant lethal leaf mutation in green gram (Phaseolus aureus) is described. The results are given below:
1. The mutant and the normal types are differentiated by one major factor pair, NN; nn.
2. The mutant breeds true only in the heterozygous condition, Nn. Only a few apparently NN phenotypes showing extreme narrowness of leaves are thrown out in the selfed progeny of the mutant and these also die without flowering.
3. In crosses of the normal X mutant, the pollen carrying the gene N is at a disadvantage as compared to that carrying n gene as the frequency of the mutant plant in the progeny is much lower than expected.
4. The narrow leaf is partially dominant over the normal leaf type. The leaves of the mutants (Nn) are intermediate between the homozygous dominant class (NN) and the normal type, nn. (Fig. 2).
