Breeding Of CMS Lines In Onion, Identification Of Molecular Markers Linked To CMS And Physiological Mechanism Of Bulb Dormancy

Allium cepa L., a biennial plant in onion genera of lily family, is not only one of the main vegetables in the world but also one main cultivar for export. However, the hybrid seeds in its production were all imported from abroad, which sharply increased the production cost. So breeders try to select cytoplasmic male sterile lines to produce hybrid and lower the cost. In this paper it studied the genetic diversity in onion germplasm, creation and utilization of new CMS material, identification of molecular markers related to CMS and explored the physiological mechanism for bulb dormancy in order to select the cytoplasmic male sterile line and utilize heterosis in onion and to breed new hybrid with good quality, high yield and long storage period, which could greatly decreased the production cost and improved its competition ability in international market. Results were as follows:In the first part, it studied the genetic diversity and made clustering analysis on quantity traits and DNA diversity in germplasm of onion. Results showed that four principal components, yield, comprehensive factor, biological growth and bulb factor, cumulative contributed 75.34% of the total resources in principal component analysis. According to maturity and yield, germplasms could be divided into three types, early maturity with middle yield, late maturity with middle yield and high yield. While through RAPD analysis, 52 germplasms were classified two types, long light time and middle light time type at the genetic distance of 0.15, which was coincided with the onion ecological classification. At the genetic distance of 0.132, the middle light time types could be divided into four kinds, early maturity with middle yield, middle or late maturity with middle yield, middle or late maturity with high yield and early maturity with high yield. These two analysis methods could be referenced each other, while the molecular clustering method was more accurate than the traditional quantitive clustering one.In the second part, it introduced the breeding of CMS lines and the utilization of heterosis in onion. In Spring of 1997, a male sterile plant was found in the elite seed field...