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A psbA mutation (Val 219 to Ile) causes resistance to propanil and increased susceptibility to bentazon in Cyperus difformis
Author(s) -
Pedroso Rafael M,
AlKhatib Kassim,
AlarcónReverte Rocio,
Fischer Albert J
Publication year - 2016
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.4267
Subject(s) - propanil , bentazon , biology , weed , chemistry , botany , weed control , agronomy
BACKGROUND Propanil‐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. RESULTS The 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. CONCLUSION The 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. © 2016 Society of Chemical Industry