Development Of Materials With Resistance To Sclerotinia Sclerotiorum In Brassica Napus

Rapeseed is china's main oil crop,we have 1/3 of the world's planting area and output. The year sown area surpasses 7 million hectares ,the annual production of rapeseed amounts to 11 million tons.Rapeseed oil accounted for about 40% of edible vegetable oils, high-quality rapeseed meal is an important protein feed.So it is significant for breeding to select the rapeseed with high yield,good quality and disease resistant.Sclerotinia stem rot which is a kind of worldwide disease cause our rapeseed serious reduction.Although many scientist have done a extensive and deepgoing research on it,the progress was so poor. Therefore exploring and breeding disease-resistant reource has became an effective means to defend Sclerotinia stem rot.We established two doubled haploid (DH) lines using microspore culture of Brassica napus. From these two DH lines, several novel disease-resistant materials were derived through the identification of disease-resistant in the field,combined with quality traits ,genetic background analysis. Meanwhile , four F₁ hybrid generations of Brassica napus L and three pol TCMS were performed microspore culture,several factors that affect microspore embryogenesis and plant regeneration of embryoids were explored and improved. The difference between two types of materials in microspore culture was compared. The results are as follows:1.Fuor F₁ hybrid generations (8-108,8-933,8-531,8-423), three pol TCMS (Yu150,P48,P49) were performed microspore culture, several factors that affected microspore embryogenesis were discussed in our experiment. The results are as follows:different materials of Brassica napus showed significant difference in ability of embryos yields, even if the same material, there was a significant difference of embryos yields among different plants; In materials 8-108and8-531, the highest frequency of embryogenesis was obtained from culture of buds sampled at 2～7d after first flowering ,but for pol TCMS, the best aging of the inflorescence was 3～6d before first flowering; The rate of plant regeneration notably increased after an initial period of clod temperature induce(8-10℃) for 15 days.Through microspore culture for F₁ generations of (7-5×Yu123 )and(7-5×95-32), we constructed successfully including 203 and 82 lines respectively, named W1-DH lines and W2-DH lines.2. When identification of disease-resistant for two DH populations in the seedling stage, we obtained 74 and 31 different genotype disease-resistant single plants respectively.3. The genetic variations of the main quality traits of two DH populations were analysed in this study. The results are as follows: According to the contrast between both of the populations, we discovered that the largest variation of the main quality traits is erucic acid content, glucosinolate and stearic acid, followed is oil content, protein content and inoleic acid content, variation of oleic acid content and inolenic acid content least. Glucosinolate content in both of the DH populations are higher than their parent.4. Genetic background of the selected DH lines was analysed by AFLP, The results demonstrated the genetic variation among DH lines was high. Based on the purpose of breeding, we chosed 13 and 9 DH lines from selected two DH lines which are closer to P2(7-5) in the genetic distance.5. After identification of disease-resistant for 13 and 9 DH lines in the adult plant stage,we derived 2 DH lines (W1-64,W1-47) with resistance to Sclewtinia stem rot nearly to the ZS9,3 DH lines (W1-188,W1-127,W1-09) with resistance to Sclewtinia stem rot nearly to the parent(Yu123). In 9 DH Lines of W2 population,6 DH lines(W2-36,W2-02,W2-37,W2-21,W2-61,W2-35) were chosen with spot from Sclewtinia stem rot were notably less than parent(95-32).6. We analysed the genetic variations of the main agronomic traits of above 11 DH lines and their parent 7-5, the average of 11 DH lines were higher than 7-5 in plant height,number of first branches,length of main infioresence and number ofSiliques of main infioresence, but except for the height of primary effective branch.