Vegetos

Abstract

Marker assisted selection (MAS) using mitochondrial DNA based marker cytochrome b (cob) was integrated with phenotypic evaluation to isolate male sterile and maintainer lines from open-pollinated onion varieties adapted to North Indian agro-climatic region. Cytotype (N/S) determination by cob marker followed by morphological and microscopic study of pollen discovered male sterile plants (Smsms) at frequencies of 0.015 in Punjab Naroya, 0.020 in Punjab Selection, and 0.006 in Punjab White. The progeny scoring of test-crosses between male sterile and N-cytoplasmic plants isolated the maintainers (Nmsms) at frequencies of 0.133 in Punjab Naroya, 0.231 in Punjab Selection and 0.182 in Punjab White. As a novel approach, Trait Recovery Programme was demonstrated to reduce the population size required to recover a male sterile plant by 91.08% in Punjab Naroya, 92.99% in Punjab Selection and 97.66% in Punjab White. For recovering a maintainer, 10% reduction in Punjab Naroya and 9.10% in Punjab Selection was calculated. However, no reduction was observed in Punjab White. This analysis also validated that in a randomly mating onion population, frequency of recessive ms allele squared is equal to the frequency of male sterile plants among S-cytotype and frequency of maintainers among N-cytotype (fms² = fSmsms/fS = fNmsms/fN).