Characterization of resistance and fitness cost of Descurainia sophia L. populations from Henan and Xinjiang, China

Descurainia sophia L. is a notorious weed in winter wheat field and has serious resistance to tribenuron-methyl. Xinjiang is a main wheat production region in China with no information on D. sophia resistance to tribenuron-methyl. Here, resistance levels of D. sophia populations to tribenuron-methyl from Xinjiang and Henan were investigated. In addition, homozygous mutation subpopulations of high resistant D. sophia populations from Xinjiang and Henan were generated and then cross-resistance and fitness cost were determined. Results showed that 5 out of 31 populations from Xinjiang developed resistance to tribenuron-methyl, including two high resistant populations (X30 and X31). While 10 out of 11 populations from Henan showed resistance to tribenuron-methyl, including three high resistant populations (H5, H6 and H7). X30 and X31 shared the same mutation type of Pro197Thr in ALS1, while the mutation type of ALS1 in H5, H6 and H7 were Pro197Ser, Pro197His and Pro197Ala, respectively. The homozygous mutation subpopulations (SX30, SX31, SH5, SH6, SH7) showed cross-resistance to flucarbazone-sodium, bensulfuron methyl and flumetsulam. Under monoculture condition, relative growth rates of SX30, SX31 were higher than susceptible population (SX13), while that in SH5, SH6, SH7 were almost same with SX13. When mix planted with SX13, SX30 and SX31 displayed weaker competitiveness than SX13, while SH5, SH6, SH7 showed stronger competitiveness than SX13. The results suggested that D. sophia from Xinjiang had low resistance frequency to tribenuron-methyl and the high resistant populations had fitness costs.