Molecular-agronomic characterization and genetic study reveals usefulness of refined Ogura cytoplasm based CMS lines in hybrid breeding of cauliflower (Brassica oleracea var. botrytis L.)

Abstract

Cytoploasmic male sterility (CMS) is the most widely used system for hybrid seed production in vegetable brassicas. Information of morphological and molecular divergence in combination with combining ability is instrumental in selecting suitable parent in hybrid development. Twenty five CMS lines developed after more than 9 generations of backcrossing were analysed for different agronomic and floral traits. Besides, they were also evaluated for combining ability to reveal their breeding potential. Two CMS lines, Ogu402-6A and Ogu76-4A were distantly placed from rest of the CMS genotypes based on morphological characterization. Molecular analysis through SSR primers also revealed the genetic distance of the CMS lines Ogu402-6A from rest of the CMS pool. Three genotypes (Ogu402-6A, Ogu76-4A and Ogu119-2A) with early maturity were identified for their use in development of short duration hybrids. Similarly, 3 CMS lines Ogu118-2A, OguHL-3A and Ogu126-1A were identified with yield potential of more than 60t/ha. Based on 13 polymorphic SSR markers 25 CMS lines were grouped into 4 major clusters. Molecular diversity in combination with agronomic characterization will be very useful in diverse parental lines. Introgression of Ogura cytoplasm into cauliflower nuclear background caused variety of flower deformities. However, these deformities were genotype specific. General combining ability (GCA) of the CMS lines revealed their potential for use in hybrid breeding. Few genotypes were identified based on combining ability for their use in development of short duration and high yielding F1 hybrids.