Molecular bases for sensitivity to tubulin-binding herbicides in green foxtail

• Published in: Plant physiology (Bethesda) Vol. 136; no. 4; pp. 3920 - 3932
• Main Authors: Delye, C, Menchari, Y, Michel, S, Darmency, H
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.12.2004; American Society of Plant Physiologists; Oxford University Press ; American Society of Plant Biologists
• Series: Focus Issue on the Plant Cytoskeleton
• Subjects: Alleles; Amino Acid Sequence; amino acid substitution; Amino acids; Base Sequence; Bioassays; Biological and medical sciences; Chemical control; Codons; Dimers; Drug Resistance - genetics; Focus Issue on the Plant Cytoskeleton; Fundamental and applied biological sciences. Psychology; Genetics; grain crops; Herbicide resistance; Herbicides; Herbicides - metabolism; Herbicides - pharmacology; Hypersensitivity; Life Sciences; Microtubules; millets; Models, Molecular; Molecular Sequence Data; Mutation; Parasitic plants. Weeds; Phylogeny; Phytopathology. Animal pests. Plant and forest protection; plant proteins; Plants; Plants genetics; Protein Binding; Protein Conformation; Seedlings; sequence analysis; Setaria italica; Setaria Plant - drug effects; Setaria Plant - genetics; Setaria viridis; Species Specificity; Three dimensional modeling; trifluralin; tubulin; Tubulin - chemistry; Tubulin - genetics; Tubulin - metabolism; Weeds; Benzoic acid; Monocotyledones; Bioassay; Hypersensitivity; Pesticides; Herbicide; Setaria viridis; Gene; Gramineae; Angiospermae; Spermatophyta; Mutation; Setaria italica; Carbamate
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.103.037432

We investigated the molecular bases for resistance to several classes of herbicides that bind tubulins in green foxtail (Setaria viridis L. Beauv.). We identified two alpha- and two beta-tubulin genes in green foxtail. Sequence comparison between resistant and sensitive plants revealed two mutations, a leucine-to-phenylalanine change at position 136 and a threonine-to-isoleucine change at position 239, in the gene encoding alpha2-tubulin. Association of mutation at position 239 with herbicide resistance was demonstrated using near-isogenic lines derived from interspecific pairings between green foxtail and foxtail millet (Setaria italica L. Beauv.), and herbicide sensitivity bioassays combined with allele-specific PCR-mediated genotyping. Association of mutation at position 136 with herbicide resistance was demonstrated using herbicide sensitivity bioassays combined with allele-specific PCR-mediated genotyping. Both mutations were associated with recessive cross resistance to dinitroanilines and benzoic acids, no change in sensitivity to benzamides, and hypersensitivity to carbamates. Using three-dimensional modeling, we found that the two mutations are adjacent and located into a region involved in tubulin dimer-dimer contact. Comparison of three-dimensional alpha-tubulin models for organisms with contrasted sensitivity to tubulin-binding herbicides enabled us to propose that residue 253 and the vicinity of the side chain of residue 251 are critical determinants for the differences in herbicide sensitivity observed between organisms, and that positions 16, 24, 136, 239, 252, and 268 are involved in modulating sensitivity to these herbicides.