关键词: 双氟磺草胺, 播娘蒿, 抗性水平, 抗性机理

Abstract:

【Background】 Descurainia sophia is the most widely distributed and harmful broad-leaved weed in winter wheat field, and florasulam is the most widely used ALS inhibitor herbicide for controlling broad-leaved weeds. After several years of application, the control effect of florasulam on D. sophia has been found to decline in some wheat fields, which may be related to the resistance. 【Objective】 The objective of this study is to clarify the resistance level and mechanism of D. sophia to florasulam, and to provide theoretical basis for the establishment of precise regional control of broad-leaved weeds in wheat field. 【Method】 A total of 40 populations of D. sophia were collected from winter wheat fields. Whole-plant dose response experiments were conducted to determine the resistance level of 40 populations to florasulam, tribenuron-methyl and MCPA in the greenhouse. At the same time, according to the ALS gene sequence of D. sophia, the genomic DNA of a single plant with high resistance to florasulam was extracted. The ALS gene sequences were obtained and compared with that of sensitive type Arabidopsis thaliana to find out the mutation site and the resistance mechanism. 【Result】 The results of resistance level determination showed that 32 of the 40 D. sophia populations were sensitive to florasulam, accounting for 80.00%. There were 3, 3 and 2 populations of low resistance, medium resistance and high resistance, respectively. JN-1, JNI-2 and LY-2 belonged to low resistance populations. Three populations LC-3, LY-4 and YT-1 belonged to medium resistance with resistance index (RI) of 49.00, 26.44 and 21.09, respectively. BZ-1 and DZ-3 belonged to high resistance populations with RI of 52.00 and 194.00, respectively. The ALS sequence analysis showed that there were mutations from CCT (pro) to TCT (Ser) or CTT (Leu) in amino acid 197 of ALS gene in BZ-1, while TGG (Trp) to TTG (Leu) in amino acid 574 of ALS gene in DZ-3. In addition, 19 of the 40 D. sophia populations were resistant to tribenuron-methyl, accounting for 47.50%, among them, 11 populations were low resistance, 6 populations were medium resistance with RI of 38.05, 13.55, 11.54, 10.45, 11.50, 11.02, and DZ-3 and LY-4 belonged to high resistance populations with RI of 244.75 and 68.50, respectively. All 40 populations were sensitive to MCPA. 【Conclusion】 Among the 40 populations of D. sophia collected from wheat fields in Shandong Province, 20.00% of them are resistance to florasulam, and the substitutions of amino acids occur in different positions in the populations with high resistance to florasulam. The resistance of D. sophia to tribenuron-methyl is still very serious, but all the populations are not resistant to MCPA. In view of the resistance area of D. sophia, the alternative and mixed use of herbicides with multiple mechanisms should be promoted, which can not only delay and control the development of resistance in weeds, but also expand the weed control spectrum and reduce the use of herbicides.

Key words: florasulam, Descurainia sophia, resistance level, resistance mechanism