Multiple Pro-197 substitutions in the acetolactate synthase of rigid ryegrass (Lolium rigidum) and their impact on chlorsulfuron activity and plant growth

作者：Kaloumenos Nikolaos S; Tsioni Vassiliki C; Daliani Eugenia G; Papavassileiou Stella E; Vassileiou Anthi G; Laoutidou Poplia N; Eleftherohorinos Ilias G^*

来源：Crop Protection, 2012, 38: 35-43.

DOI：10.1016/j.cropro.2012.03.002

• ALS sequence
• Herbicide resistance
• Growth rate
• Cytochrome P450

The evaluation of 21 Lolium rigidum accessions for chlorsulfuron resistance in a whole-plant response experiment indicated that 10 accessions were highly resistant (R) to chlorsulfuron, three partially resistant (r) and seven susceptible (5) to this herbicide. The excellent control of the r accessions in the presence of terbufos provided strong evidence for the existence of herbicide metabolism resistance due to cytochrome P450 enzymes. The sequence of 34 L rigidum plants from the 10 R accessions revealed that all mutant ALS alleles encoded an amino acid replacement at codon 197, which resulted in the substitution of Pro-197 by Ala, Arg, Gln, Leu, or Ser and probably His or Val. Most of the R accessions revealed more than one mutation and among them the Pro-197 by Ala was the most common, whereas twelve out of the 34 R sequenced individual plants were homozygous. The sequence of 12 and 9 L rigidum plants from the respective four S and three r accessions did not indicate any ALS mutation at the codon 197. ALS activity assays confirmed the whole-plant response experiments and the ALS gene sequence results. The resistance ratios (R/S) for the R accessions ranged from 36 to 620 showing that ALS gene mutations resulted in less susceptible to chlorsulfuron ALS enzyme. The R/S values for the r accessions were similar to the S-control accession. The growth rate evaluation of four R and four S L rigidum accessions in the absence of competition indicated that the R accessions had similar growth pattern to that of S accessions, suggesting that the resistance-endowing ALS mutations did not result in detectable resistance fitness cost.

• 出版日期2012-8