Estimation of the Frequency of Functioning Gametes in Monosomics

IN monosomics, two types of gametes having n and ( n –1) chromosomes are formed, and the segregation of the three types of plant, 2 n (disomic), 2 n –1 (monosomic) and 2 n –2 (nullisomic), in the progeny of a monosomic is dependent on the frequencies of the n and ( n –1) chromosome gametes on the male and female sides. The functional frequencies of n and n –1 male and female gametes can be determined experimentally by making reciprocal crosses between a normal plant and a monosomic. Estimates of the frequencies of n and n –1 gametes on either the male or the female side can be obtained from the observed numbers of disomics, monosomics and nullisomics when the frequencies of gametes on one side are known.