Development of rice (Oryza sativa) lines resistant to aryloxyphenoxypropionate herbicides through induced mutation with gamma rays

The aryloxyphenoxypropionate herbicides (APPs) are graminicides with excellent control of many grass weeds species, including weedy rice (Oryza sativa L.). These herbicides block the fatty acid biosynthesis by inhibiting the enzyme acetyl-CoA carboxylase (ACCase), resulting in the death of susceptible plants. Inducing mutation with gamma rays to rice seeds, two lines resistant to APPs herbicides were developed. Plant dose-response assays confirmed the resistance to the APPS herbicides quizalofop-p-ethyl and haloxyfop-p-methyl. The carboxyltransferase domain fragments of ACCase from the resistant biotype and susceptible control were sequenced and compared. A point mutation was detected in the amino acid position 2,027 (Rice Genome Annotation Project: Os05g22940.1). Results indicated that resistance to APPs is a consequence of an altered ACCase enzyme that confers resistance. The use of APPs herbicide-resistant rice lines represents an innovative and promising alternative for weedy rice control in paddy rice systems.