Alopecurus aequalis
Sobol. is a common grass weed,
which has become increasingly troublesome to control in
China wheat fields. One
A. aequalis population, collected
from Anhui Province China, was suspected to be resistant
to fenoxaprop-
P-ethyl and mesosulfuron-methyl. This
study aimed to establish the cross-resistance pattern using
the purified subpopulation and explore the potential targetsite
and non-target-site based resistance mechanisms.
Sequencing results showed that a single nucleotide change
of ATT to AAT was present in acetyl-CoA carboxylase
(ACCase) gene of the resistant (R) plants, resulting in
an Ile
2041Asn amino acid substitution. Besides, another
single nucleotide change of CCC to CGC was present in
acetolactate synthase (ALS) gene of the R plants, resulting
in a Pro
197Arg amino acid substitution. The homozygous
resistant plants were isolated and the seeds were used
in whole-plant herbicide bioassays. Compared with the
susceptible (S) population, R population displayed high
level resistance to fenoxaprop-
P-ethyl and mesosulfuronmethyl.
Cross resistance patterns showed that the R
population was highly resistant to clodinafop-propargyl,
moderately resistant to pyroxsulam and flucarbazoncsodium,
lowly resistant to pinoxaden, and susceptible
to tralkoxydim, sethoxydim, and isoproturon. The
pretreatment of piperonyl butoxide reduced the 50%
growth reduction (GR
50) value of fenoxaprop-
P-ethyl,
suggesting that target-site resistance and non-target-site
resistance mechanisms were both present in fenoxaprop-
P-ethyl-resistance of
A. aequalis. This is the first report
of ACCase Ile
2041Asn and ALS Pro
197Arg mutation in
A. aequalis.
