Abstract:
The herbicide quinclorac is widely used to control rice weeds worldwide. Echinochloacrus galli var. mitis has never been reported for quinclorac resistance. However, due to the prolonged use of quinclorac in Chinese rice fields, resistance to this herbicide has emerged in this species. In this study, we investigated the mechanism of quinclorac resistance in four different E. crusgalli var. mitis biotypes from three Chinese provinces. The resistant biotypes had lower levels of 1-aminocyclopropane-1-carboxylic acid (ACC) content, ACC synthase and oxidase activities, and less inducible ACS and ACO gene expressions than the susceptible biotype. This indicates that there is a positive correlation between quincloracresistance and ethylene biosynthesis inhibition. The resistant biotypes had higher ß-cyanoalanine synthase (ß-CAS) activity than the susceptible biotypes. This is important because cyanides produced during the ethylene biosynthesis pathway are mainly degraded by ß-CAS. Additionally, nucleotide changes were identified in the EcCASgene of resistant biotypes that resulted in three amino acid substitutions. This altered the enzyme structure, increased binding residues in the active site with its cofactor, and decreased binding free energy. Consequently, the activity of EcCAS was higher in resistant biotypes. Taken together, our results suggest that the alteration in ethylene response pathway or at least variation in ACC synthase and ACC oxidase enzyme activities, as well as enhanced ß-CAS activity and mutation in the EcCASgene expression, could be considered as a probable mechanism of quinclorac resistance in E. crus-galli var. mitis.
Page(s):
74-74
DOI:
DOI not available
Published:
Journal: Abstract Book on Second International Conference on Recent Approaches in Plant Sciences (RAPS-23) 4-5 May 2023 , Volume: 0, Issue: 0, Year: 2023
Keywords:
quinclorac resistance
,
ACS and ACO genes
,
Ethylene biosynthesis inhibition
,
ACC synthase and ACC oxidase
,
ßcyanoalanine synthase