Stability Identification Of Clonal F₂ Population In Rapeseed (Brassica Napus L.) By Molecular Markers On Agronomic Characters

Rapeseed is a worldwide important oil crops, also is a key resource of main edible oil and protein feed, so rape breeding workers attach importance to it. The development and application of molecular biophysical techniques supply an efficient means to the scientific research in rape, and bring creative methods to rape breeding.In order to identify the efficiency of clonal F2 population as a repetitive colony in the genetic mapping, plantlets were regenerated by tissue culture of F2 rapeseeds (Brassica napus L.). A clonal F2 population of rapeseed was propagated by stem tip, cotyledon and hypocotyls of the plantlets. This essay focused on the agronomic characters of the regeneration plants, identified the variation by SSR markers. Besides, the variety of regenerated plantlets between different explants in the same condition is primarily studied on the molecular level. And the main conculusions are as follows:1. The frequencies of stem tipes differed among F2 segregation populations in the first subculture. Under the same condition of culture, with the increasing of subculture, the frequencies of stem tipes increased, almost 100%, so it indicated that multi-subculture could reduce the affect -rapeseeds (Brassica napus L.) genotype affect regeneration frequencies of stem tipes.2. Under certain conditions as genetic background and cultural environment, shoot regeneration frequencies varied significantly from different explants, the rate of frequency in cotyledon was much more higher than that in hypocotyls; when the material was changed, there was almost equality in cotyledon, while difference in hypocotyls.3. The regeneration plants 119 materials of F2 clonal population from stem tipes growed uniformly in lines in seedling stage; in bud and stooling stage, size and shape of plants exhibited basic accordance, except partial dwarfish plants. However, in one line a plant's characters—size, shape of leaf and stem, had variation. Young blooming period of all plants concentrated mainly between 5d and 12d, but individuals of ten lines exceeded I5d, advanced bloom. The result of analysis about CV (coefficient of variation) in R₁ generation suggested that variation in zero point for 1st branches was the highest, and it's frequency of variation was 44.54%; while main inflorescence length and pod length had no variation; variation in stem heigth, No. of 1st branches and effective length of main inflorescence were low; pods per plant, No. of pods of main raceme and seeds of per pods displayed evident variation, due to affect of the environment and management.4. SSR amplified with 100 pairs of primers, which cover the whole rapeseed (Brassica napus L.) genome using the parents DNA as template. Clone 03H109 were studied using SSR by 20 pairs with polymorphism selected from those 100 pairs. 1 DNA polymorphism was found in the stem tip...