Patterns of anthocyanin inheritance in rice VI. two cases of six gene segregation

1. The article reanalyses two cases of inheritance of anthocyanin pigment. The first case is that of Pookhi × Murmagar, a cross made by Hector (1922). The other case is of the cross of Akage × Kuro-Mochi made by Nagao (1951). Originally the two cases were explained by these authors on three gene basis. The reanalysis revealed that in both the crosses six genes are involved but the nature and interaction of genes are entirely different in the two cases resulting in different patterns of inheritance.

2. In the cross Pookhi × Murmagar there is a basic chromogen gene, C, which is essential for colour production. There are two duplicate antho-cyanin sheath genes which, in the presence of the chromogen gene, produce colour in the sheath group which consists of sheath, internode, stigma and apiculus. Besides these sheath genes there are three genes for ligule and glumes. The two sheath genes have differential reaction.

3. The two ligule genes, Lgp₁ and Lgp₂ act as a complementary pair in the presence of chromogen gene, to produce colour in sheath group only, even when the sheath genes are absent.

4. The third ligule gene, Lgp₃, produces colour in both ligule and glumes simultaneously only when the chromogen gene and both the sheath genes are present.

5. How the various classes are formed has been shown by indicating the frequencies of various phenotypes which make up the various classes found by Hector.

6. In the case of Nagao's cross between Akage × Kuro-Mochi it was found that, besides the basic chromogen gene, C, there were triplicate genes, Ap₁, Ap₂, Ap₃ for pansy-purple colour instead of only one gene. The chromogen gene and any one of the pansy-purple colour gene are required to develop black violet by the gene A^v; which is epistatic to Ap genes. There is a separate spreader gene which extends colour from Apiculus to lemma and palea. How different classes are formed has been shown in this case also.