Gamma-rays in the development of rice lines tolerant to aryloxyphenoxypropionate herbicides.

Abstract The aryloxyphenoxypropionate (APP) herbicides are graminicides with excellent control of many grass weed species, including weedy rice (Oryza sativa L.). These herbicides block fatty acid biosynthesis by inhibition of the enzyme acetyl-CoA carboxylase (ACCase) and cause death of the plant. Through induced mutation of rice seeds with gamma-rays, rice lines resistant to APP have been developed. Plant dose-response assays confirmed resistance to the APP herbicides quizalofop-p-ethyl and haloxyfop-p-methyl. The carboxyl-transferase (CT) domain fragments of ACCase from the resistant line and the susceptible control were sequenced and compared. A point mutation was detected in the amino acid position 2027. Results indicated that resistance to APP herbicides is a consequence of an altered ACCase enzyme that confers resistance. APP-resistant rice provides an option to improve the efficiency of weed management in rice crops.