Inheritance of anthocyanin pigmentation in leaf blade of rice (Oryza sativa L.)

Abstract

Three leaf blade pigment patterns viz., purple (Strain CP.12), purple wash (Strain CH.17) and faint purple wash (Strain CH.17 mutant) have been described. The mode of inheritance of anthocyanin pigmentation in the leaf blade has been studied by making inter-crosses between the three pigmented types and between these pigmented and several green leaf blade types. A six factor hypothesis showing the role of each gene and its relationship with others is presented to explain this inheritance. The F 2 segregation of 13:3, 55:9 and 229:27 of green: purple leaf, obtained in crosses between CP.12 × HS.22, CP.12 × T.1029/2 or CP.12 × T.786 and CP.12 × T.136 respectively is due to two, three and four gene differences respectively between the parents crossed; one of these genes is an inhibitory factor which suppresses the expression of purple pigment. The 9:7 and 27:37 ratios of purple wash: green in crosses between CH.17 and green leaf blade varieties are due to the interaction of two and three complementary genes respectively. The F 2 segregation of 39 purple wash:12 purple:13 green obtained from the cross CP.12 × CH.17 (purple × purple wash) is shown to be due to interaction of complementary factors and presence of an inhibitory gene Ilp, the latter being epistatic over gene Lp for purple colour. The four factor segregation of 117PW: 36P: 48FPW: 55G in the cross CP.12 × CH.17mutant, is shown to be due to interaction of four complementary genes one of which is a lower allele Ld' and the other an inhibitory factor Ilp. The monogenic segregation obtained from the cross CH.17 × CH.17 mutant is shown to be due to a single factor difference Ld-Ld'. The occurrence of purple wash leaf blade phenotype along with the faint purple wash and green leaf blade phenotypes in the F 2 of the cross AC.16 × CH.17 mutant (G × FPW) has been explained as being due to the presence of the higher allele Ld in AC.16 as against the lower allele Ld' present in CH.17 mutant. Some of the anomalous ratios like 3 green: 1 purple, 10 green: 1 purple and 8.3 green: 1 purple reported by previous workers have been explained on the basis of the six factor hypothesis.