A psbA mutation (Val(219) to Ile) causes resistance to propanil and increased susceptibility to bentazon in Cyperus difformis

作者：Pedroso Rafael M; Al Khatib Kassim^*; Alarcon Reverte Rocio; Fischer Albert J

来源：Pest Management Science, 2016, 72(9): 1673-1680.

DOI：10.1002/ps.4267

• herbicide resistance
• propanil
• bentazon
• Cyperus difformis
• Oryza sativa
• psbA gene

BACKGROUNDPropanil-resistant (R) Cyperus difformis populations were recently confirmed in California rice fields. To date, propanil resistance in other weed species has been associated with enhanced aryl acylamidase (AAA)-mediated propanil conversion into 3,4-dichloroaniline. Our objectives were to determine the level of propanil resistance and cross-resistance to other PSII inhibitors in C. difformis lines, and to elucidate the mechanism of propanil resistance.
RESULTSThe propanil-R line had a 14-fold propanil resistance and increased resistance to bromoxynil, diuron and metribuzin, but not to atrazine. The R line, however, displayed a fourfold increased susceptibility to bentazon. Interestingly, susceptible (S) plants accumulated more 3,4-dichloroaniline and were more injured by propanil and carbaryl (AAA-inhibitor) applications than R plants, suggesting that propanil metabolism is not the resistance mechanism. psbA gene sequence analysis indicated a valine-219-isoleucine (Val(219)Ile) amino acid exchange in the propanil-R chloroplast D1 protein.
CONCLUSIONThe D1 Val(219)Ile modification in C. difformis causes resistance to propanil, diuron, metribuzin and bromoxynil but increased susceptibility to bentazon, suggesting that the Val219 residue participates in binding of these herbicides. This is the first report of a higher plant exhibiting target-site propanil resistance. Tank mixing of bentazon and propanil, where permitted, can control both propanil-R and propanil-S C. difformis and prevent the spread of the resistant phenotype.

• 出版日期2016-9