Genetics of novel corolla colours in periwinkle

Abstract

Inheritance of a novel corolla colour in periwinkle [Catharanthus roseus (L) G. Don], viz. magenta, was studied by crossing an accession MJ, possessing this corolla colour, with cultivar Nirmal, possessing white corolla. The accession MJ was also crossed with another accession OR, possessing another novel corolla colour, viz. orange-red, to determine the relationship between genes governing magenta corolla and orange-red corolla. The F 1 plants of the cross MJ× Nirmal had pink corolla and red eye. In the F 2 generation, five kinds of corolla colours were observed: (i) pink corolla and red eye, (ii) rose corolla and red eye, (iii) magenta corolla and red eye, (iv) white corolla and red eye and (v) white corolla. The observed frequencies of the five kinds of plants fitted a ratio of 144:27:9:12:64. The progeny of the backcross, F 1 × MJ, segregated into three kinds of plants, (i) pink corolla and red eye, (ii) rose corolla and red eye and (iii) magenta corolla and red eye, in the ratio of 2:1:1, while the backcross, F 1 × Nirmal, segregated into two kinds of plants, (i) pink corolla and red eye and (ii) white corolla, in the ratio of 1:1. Two new genes (proposed symbols O m and J) appeared to be involved in the determination of magenta and rose corolla colours. Interaction between four independent genes R, W, O m and J, appeared to explain the observed segregation in the cross MJ × Nirmal. The F 1 plants of the cross MJ × OR had scarlet-red corolla and red eye. The segregation data of F 2 and backcross generations suggested that genes governing orange-red corolla and magenta corolla were allelic to each other. Two new and non-parental corolla colours viz., rose corolla and scarlet-red corolla, were observed in the progeny of the crosses of the present study.

Construction of genetic linkage map of the medicinal and ornamental plant Catharanthus roseus

“…Segregation patterns of the six characters studied fitted the Mendelian 3:1 ratio. In this study the inheritance pattern of the corolla petal colour, known to be multigenic in other studies (Kulkarni et al 2005), was seen to be monogenic. The distances between morphological markers that colocalized on LG1 and LG8 was large (from 3.1 to 9.1 cM), such that their coordinated regulation based on linkage is not indicated.…”

Breeding medicinal plant, periwinkle [Catharanthus roseus(L) G. Don]: a review

“…Mode of inheritance of other corolla colours viz., orange-red corolla and magenta corolla and the presence or absence of red eye has also been studied (Sreevalli et al, 2002; Kulkarni et al ., 2005b, 2008). Epistatic interactions between independently inherited genes R, W, B, I, O, O m , J and E were found to be responsible for the production of pink, white, violet, pale pink, orange-red, magenta, scarlet-red and rose corolla with or without red eye (Supplementary Fig.…”