Acetohydroxyacid synthase (AHAS) amino acid substitution Asp376Glu in Lolium perenne: effect on herbicide efficacy and plant growth

• Published in: Journal of plant diseases and protection (2006) Vol. 123; no. 4; pp. 145 - 153
• Main Authors: Menegat, Alexander, Bailly, Geraldine C., Aponte, Raphael, Heinrich, Gregor M. T., Sievernich, Bernd, Gerhards, Roland
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer 01.08.2016; Springer Berlin Heidelberg
• Subjects: Agricultural Science; Amino acid substitution; Amino acids; Biomedical and Life Sciences; Enzymes; Genetic mutation; Genetics; Genotypes; Herbicide resistance; Herbicides; Jordbruksvetenskap; Life Sciences; Original Article; Plant Pathology; Plant Physiology; Plant Sciences; Root biomass; Tillers; Herbicide resistance; Perennial ryegrass; AHAS
• ISSN: 1861-3829; 1861-3837; 1861-3837
• DOI: 10.1007/s41348-016-0023-2

Recently, the acetohydroxyacid synthase (AHAS) amino acid substitution Asp376Glu was detected in a Lolium perenne population originating in France. This is the first documented occurrence of the Asp376Glu single-nucleotide polymorphism in a Lolium species. The effects on herbicide efficacy and plant fitness are presented. Separation of the original population into different genetic subgroups allowed the comparison of different L. perenne AHAS genotypes according to their susceptibility to AHAS-inhibiting herbicides. Root and shoot biomass accumulation as well as tiller production was analysed for resistant and sensitive populations. Genotype-specific AHAS activity and inhibition were studied in vitro, using recombinant Arabidopsis thaliana DNA. Plants expressing the AHAS Asp376Glu genotype were resistant against mesosulfuron + iodosulfuron, pyroxsulam and propoxycarbazone. To imazamox, reduced susceptibility for dosages below 140 g a.i. ha⁻¹ was observed. In the absence of herbicide, no significant impact of the Asp376Glu genotype on shoot biomass and tiller accumulation could be observed, whereas root biomass of the Asp376Glu genotype was significantly reduced by 68 % compared to the AHAS genetic wild type. The AHAS enzyme study revealed reduced AHAS enzyme rate of 48 % for the Asp376Glu genotype compared to the AHAS genetic wild type. This study highlights the role of the amino acid exchange on resistance profile against the most relevant AHAS-inhibiting herbicides. First indications were found that fitness of the Asp376Glu genotype is hampered.