| On the occurrence of chlorophyll mutations in clusters
in einkorn wheat T. FUJII National Institute of Genetics, Misima, Japan Dormant seeds of Triticum monococcum were subjected to 10, 20 and 30 kr of gamma - rays. All spikes from all X1 individuals were harvested and chlorophyll mutations were scored in the X2 - seedlings. Number of spikes with chlorophyll mutants increased with increasing dosage. In some cases, several spikes proved to carry the same kind of mutation from the same X1 individual. Namely, 8 spikes among 16 from one individual segregated albina, while in another case, only one spike among 60 spikes xantha was found. Thus distribution of cluster mutations showed a wide variation, and the average number of cluster mutants per X1 individual was not related to dosage. Frequency distribution of cluster mutants of albina type was calculated according to KONDO (cf. KONDO, S. 1961, Jap. Jour. Genet. 36 : 6 - 17 ), as given in Table 1. According to the results, the minimum number of original cells in embryonic stage was estimated as 35+ or -3, and some of these differentiated cells seem to have furnished the initials for the spikes. |