| Sclerotinia sclerotiorum and lodging are two important factors affecting oilseed rape production in China. They not only decrease oilseed yield, but also reduce the qualities of the processed oil and harvest index. Although traditional breeding strategies or transformation of OXO, chitinase andβ-1, 3-glucanase genes could increase S sclerotiorum resistance for Brassica napus partly, the S sclerotiorum resistant breeding has still not been made substantial progress because of absence of resistant resources. And the study of lodging is just beginning in and out of China. It is important to explore a new method for improving the disease and lodging resistance of oilseed rape and other crops.Most lignin distributes in the plant lignification mechanical tissue and vascular tissue's cell wall.It has increased the cell wall intensity and enhanced the ability of the cell wall watertightness and stem's mechanical strength, as well as the liquid-transporting ability. Moreover, it also plays an important role in the cell's resistant function. Being at a central position in lignin biosynthesis, 4-CL can conduct metabolic intermediates into lignin biosynthesis pathway, and is also taken as an ideal target gene for manipulating lignin biosynthesis. And F5H (Ferulate 5-hydroxylase) is also an important enzyme for conducting the biosynthesis of lignols. In this study, we firstly isolated 4-CL cDNA from Populus tremuloides, and transformed it into Brassica napus. Then we analyzed the correlation of lignin content and S sclerotiorum and lodging resistance of the heterogeneous 4-CL transgenic T2 lines. Through the over-expression of the heterogeneous 4-CL gene in B. napus, we studied the effects of altered 4-CL activity on lignin content, S. sclerotiorum and lodging resistance for the transgenic crop. And we also cloned a 4-CL gene sequence from Brassica napus by the method of homologous sequence and the biochemical function of the gene was analyzed. Furthermore we also transformed the antisence F5H gene into B.napus in order to study the relationship between the expresstion of Ferulate 5-hydroxylase and the conduction of lignin biosynthesis. These works could help us to lay a foundation for yield, quality and adversity resistance breeding of B. napus.It also play a significant result for the improvement of disease and lodging resistance through the increase of lignin content by the way of engineering technology and provide a new viewpoint way for the study and breeding of disease and lodging resistance of other crops. The results obtained were primarily as follows:1. The previous work has got the the heterogeneous 4-CL transgenic Brassica napus with overexpressing Populus tremuloides 4-CL gene. After Kan selection and PCR analysis, we chose 10 plants of the transgenic T2 line to do RT-PCR analysis, and found that the heterogeneous 4-CL gene was inheritanted firmly and expressed well in B.napus.2. It had been analyed that the fugus spots areas of S sclerotiorum on leaves, and the spot on transgenic T2 lines were smaller than the WT, and just 45.78%～65.23% of the WT, so they are significantly different(P〈α=0.01); the result of push resistance is that the transgenic lines were higher than the WT with the increase from 17.81% to 47.94%, even to 89.04%. It had been chosen 10 plants from the transgenic lines to analyse the lignin content,the result indicated that it has significantly increased, the biggest amplitude are 14.24% and 22.47%.3. A 4-CL cDNA was isolated from Brassica napus. The DNA sequence analysis and the phylogenic analysis showed that the B.napus 4-CL was phylogenically related to Arabidopsis thaliana 4-CL1(AF041049)which is involved in lignin biosynthesis.4. In the previous work,the plant expression vector pBnF5H had been constructed. It was transformed into Brassica napus cultivars, Zhongshaung No. 9. 5 transgenic plants with Kan resistance were obtained. But the T1 lines of antisense F5H transgenic plants didn't have the sequence of antisense F5H gene among the PCR analysis, so that the antisense F5H gene may be lost in the inheritace of the offsprings.
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