Genetic Variation Of Double Haploid Populations Derived From Restorer Lines Of Polima Cytoplasmic Male Sterile In B.napus

Utilization of heterosis in rapeseed is an important way to increase yield andimprove quality. Male sterility has been widely used in the heterosis breeding program inrapeseed. And development of male sterility lines and restore lines plays an significantrole in utilization of cytoplasmic male sterility in rapeseed. Since spontaneous male sterileplants were found in Polima cytoplasmic male sterility (Pol CMS) by Fu in 1972, PolCMS has become the most valuable CMS in application. In order to make full use of thisCMS and improve the yield, quality and resistance of hybrid, developing a elite restorerline, with high restorability, fine economic and agronomic traits and high combiningability, has been a crux in hybrid rapeseed production. In addition, since the developmentof the isolated microspore culture technique for the production of homozygous doubledhaploid (DH) lines in oilseed rape (Brassica napus L.) by Lichter in 1982, the techniqueof doublehaploid breeding has become a effective and rapid tool for the production ofhigh-quality hybrid in oilseed rape.Therefore, microspore culture of Brassica napus was carried out in the present study,several factors that affected microspore embryogenesis and plant regeneration ofembryoids were explored and improved. Two double haploid populations derived fromrestorer lines were constructed successfully. Genetic diversity of DH was analysed byAFLP. Additionally, the main agronomic traits and quality traits of two DH populationswere investigated in field and laboratory, respectively. Then the genetic variations of thesetraits were analysed in this study. The main results are as follows:1. The materials of Yu137,Yu127,P63,P64,P66 were performed microspore culture,several factors that affected microspore embryogenesis were discussed in our experiment.The results are as follows: The microspore embryogenic ability is controlled by genotype,and different genotypes of Brassica napus showed significant difference in ability ofembryos yields. Not only could Solid-liquid double-decker culturing significantlypromote the embryogenic of embryoids, but also are conducive to the growth anddevelopment of embryos. And activated charcoal can promote the embryogenesis ofembryoids remarkably, especially some materials that have poor embryogenesis ability. 2. The embryoid of several Brassica napus L. was studied in the present study, severalfactors that affected plant regeneration ability were discussed in our experiment. Theresults are as follows: The genotype affected plant regeneration of microspore embryoids.And the correlation analysis indicated that plant regeneration of embryoids significantpositively related to microspore embryogenic ability. The plant regeneration frequencywas closely related to embryo developmental stage, the bigger the embryo was, the easierto become seedlings, and the seedlings mostly came from the ripen cotyledonary embryos;The low-temperature pretreation on embryoids at 5℃could promote plant regeneration ofembryoids remarkably, The medium B5 with 0.1 g/l 6-BA could increase the frequency ofplant regeneration of embryoids.3. The doubled haploid (DH) population derived from restore lines Yu-137 andYu-127 by microspore culture were constructed successfully including 556 and 195 linesrespectively.4. Genetic diversity of the DH lines from Yu-137 was analysed by AFLP, And theresults demonstrated the genetic variation among DH lines was relatively small. The 8.4%average polymorphism of amplified products was detected in our experiment, and therange of similarity coefficient(SC) in the DH line population varies between 0.76-0.99, Ifclassified at the 0.94 SC level, the DH population was divided into 37 subgroups.5. The genetic variations of the main agronomic traits and quality traits of two DHpopulations were analysed in this study. The results are as follows: Both of the DH linepopulations appeared genetic variations in all of the main characters. According to thecontrast between both of the populations, we discovered that the variation trend of themain agronomic traits and quality traits of two DH line populations are consistent, onlythe difference was observed in the range of variation. The largest variation of the mainagronomic traits is yield per plant and siliques per plant, followed with numbers of firsteffective braches, height of primary effective branch, seeds per silique and 1000-seedweight. The smaller relatively coefficient of variation include plant height, length of maininflorescence, number of siliques on first inflorescence and length of silique. The largestvariation of the main quality traits is erucic acid content, glucosinolate and stearic acid,followed with oil content, oleic acid content and protein content, The variation of inolenic acid content, inoleic acid content and palmitic acid content is the least.