Estimation of Linkage and Penetrance Parameters in a Study of Petal Color in the Pigeon Pea.

HE genetics of petal color and venation in the papilionate flower of the pigeon pea (Cajanus mian (L.) Millsp.) has been reported by DAVE (1934) and MENEZES (1 956), who postulated four or five independent loci to govern these characters. In the present study of six different intervarietal crosses, however, evidence was obtained for a different and relatively complex genetic basis involving linkage, epistasis and also incomplete penetrance at a locus determining the type of venation. Several authors have recently considered the effect of such disturbing factors as differential viability, or misclassification due to incomplete penetrance, on the estimation of recombination values (BAILEY 1950; SANCHEZ-MONGE 1952). ALLARD and ALDER (1 960) developed formulae for the simultaneous estimation of linkage and penetrance parameters by the method of maximum likelihood, and illustrated their application with an interesting example of the r locus in lima beans, which governs hypocotyl color in seedlings as well as seed coat color (ALLARD 1953). In the present paper some data on the inheritance of petal color and venation are analysed using the estimation methods analogous to those given by ALLARD and ALDER (1960).