Behavior of Gene Controlling Synthesis of Purple Colour in Purple Glutinous Rice (Oryza sativa L.)

Abstract

Behavior of genes controlling the synthesis of purple colour in purple glutinous rice has not widely been recognized. Investigation would benefit many breeding programs in which morphological marker is needed. To investigate the action, F1 and F2 hybrids were produced through hybridization between the female purple rice cultivar (Kumdoisaket) and the male white rice cultivar (Niaw Sanpathong). Experiments were carried on during 1997- 1999 at the experiment field of the Faculty of Agriculture, Chiang Mai University. The results showed that, two genes (Aa and Cc) were responsible for purple colour synthesis in rice plant. The results in F1 demonstrated dominance action of the purple colour over the white on ligule, auricles, internode, apiculus and stigma where as on seedlings, leaf-sheath and leaf-blade, the action was incomplete dominance as the traits of the F1 were greenish-purple in colour. In F2, the ratio of 9 purple : 7 green was manifested on ligule, auricles, internode and apiculus while for stigma the ratio was vice visa, demonstrated the complementary gene action of epistasis in which recessive genes “a” and “c” were epistatic genes. The ratio 1 purple : 8 greenish-purple : 7 green manifested on seedling, leaf-sheath and leaf-blade was a new and of excitement, indicated the semi-epistatic action of semi-dominant genes. In consequence, the genotype of purple colour would be the all-dominant genes for both loci (CCAA). The “C_A_” genotype produced the greenish-purple colour and the “C_aa, ccA_ and ccaa” responsible for the green colour. However, the colour produced on husk and pericarp were of exception. In F1’s, husk and pericarp produced the same colour as to thecolour of the female Kumdoisaket parent, drawn out the action of complete dominance. But in F2 the heterotic effect of the F1’s heterozygous was lost. The F2 ratio shows no correspond-dance to any of the dihybrid ratio. In fact, the frequency of the F2 phenotypes distributed continuously, indicates the polygenic inherited of the two genes (C and A) differ action from the other traits.