Molecular basis of cross-resistance in Sagittaria trifolia L. against acetolactate-synthase inhibitors

Abstract

Herbicide resistance to sulfonylureas in Sagittaria trifolia L. is a common problem in northern China. In our study, we used whole-plant dose-response, acetolactate synthase (ALS) sequencing, and ALS enzyme activity methods to assess 3 putative resistant (LN-1, LN-2, and LN-3) and one susceptible (S) S. trifolia populations for crossresistance to ALS inhibitors (bensulfuron-methyl, ethoxysulfuron, pyrazosulfuron-ethyl, penoxsulam, pyribenzoxim, and bispyribac-sodium). Regarding the whole-plant dose-response and the in vitro ALS assays, the results showed that the LN-2 population evolved cross-resistance to all herbicides tested whereas the other two populations showed crossresistance only to bensulfuron-methyl, ethoxysulfuron, pyrazosulfuron-ethyl, and penoxsulam. Results of the in vitro ALS assays were consistent with whole-plant dose-response data. The DNA sequencing of the ALS gene showed that LN-1 and LN-3 populations had a single nucleotide polymorphism in the Pro 197 codon, resulting in the substitution of proline (Pro) by serine (Ser) and leucine (Leu), respectively. However, the LN-2 population showed single nucleotide polymorphism in the second position of the Asp 376 codon, causing substitution of aspartic acid (Asp) by glutamic acid (Glu). The cross-resistance of the S. trifolia population to all ALS inhibitors due to Asp 376 mutation in the ALS gene of this species is reported for the first time.

Physiological and Biochemical Responses of Sagittaria trifolia L. to Phytotoxic Ethyl Acetate Fungal Extract from Curvularia lunata Strain CLST-01

“…The threeleaf arrowhead (Sagittaria trifolia L.) is a perennial aquatic plant that belongs to the Alismataceae (water plantains family), and is a serious weed in paddy fields in northeast China [1,2]. It drastically reduces the yield of crops by competing with cultivated crop plants for growth factors, including nutrients, water, light and space [3].…”