Charaterization Of Resistance To Tribenuron-methyl In Rapeseed (Brassica Napus L.) And Development Of Transgenic Rapeseed With Herbericide-resistance

With the rapid development of China’s national economy, a large number of young andmiddle-aged labor force in rural areas has been transferred to the city.The mechanization hasbecome the main direction of the rapeseed industry. Comprehensive control of weeds is thekey to this mechanization of rapeseed industry. It is important to control and extirpate weedseffectively. It is one of the most effective ways to control weeds by using theherbicide-resistant rapaseed.In this study, First, Zhongshuang No.9rapeseed was used as the material to investigatethe suitable concentration of tribenuron-methyl and screening index.The result indicated thatphytotoxicityindex, inhibition ratio of leaf number, inhibition ratio of leaf angle significantlycorrelated with death ratio, so they were recommended as key index for tribenuron-methylresistance screening at seedling stage.Seedlings of49different genotypic rapeseedaccessionswere foliar sprayed with2.0ug/mL-1tribenuron-methyl solution screened out in the aboveexperiment. All49rapeseed accessions were classified into three groups based on the averagesubordinate function (AS)calculated by phytotoxicityindex, inhibition ratio of leaf number,inhibition ratio of leaf angle and death ration.Two accessions were grouped into the lowsensitive material (AS<of0.33),22accessions intothe moderately sensitive material (0.33≤AS<067),25accessions into highly sensitive materials (AS≥0.67). Although there existedsome difference among the tested materials to tribenuron-methyl, their resistance totribenuron-methyl is very low compared with the recommended concentration oftribenuron-methyl for weed control in wheat field. These results suggested thatbreedingpotential of rapeseed varieties with resistance to tribenuron-methylis limit by using thegenetic variation within B. napus genepool.Forty-nine B. napus accessions were analyzed for their ALS1and ALS3genes. Theresults showed that these two genes were conservative in different rapeseed accessions. Therelationship between structure of these two genes and their resistance to tribenuron-methyl.remained unclear.After treated by tribenuron-methyl foliar spray, the activity of acetolactate aynthase（ALS） reduced and the activity of glutathione transferases (GSTs) decreased first andincreased later in leaves of three rapeseed accessions with different resistace totribenuron-methyl. The ALS relative activity in the more resistant accession was higher thanthe other two accessions with lower resistance. While the GSTs relative activity in the more resistant accession decreased slowly. The peak of GSTs relative activity, which appeared6days after tribenuron-methyl treatment, was also higher in the more resistant accession thanthe other two accessions with lower resistance. The different metabolizing ability oftribenuron-methyl by GSTs may be one of reasons for different resitance to tribenuron-methylin rapeseed.Commercial rapeseed cultivars with excellent quality,2011Gr-1and2011Gr-2, wereimproved through the MAS strategy in a backcross project with resistace accessions C5(C9)as donor parent of resistance gene bar (gox). In each backcross generation, we selected theprogenies with gene bar or gox by PCR. In advanced backcross generations, the SSR markerwill be used to text genetic background response rate. Bar and gox were successfullytransferred into rapeseed. The plants showed stable resistance to glufosinate (glyphosate).