Alpha-tubulin missense mutations correlate with antimicrotubule drug resistance in Eleusine indica.
Dinitroaniline herbicides are antimicrotubule drugs that bind to tubulins and inhibit polymerization. As a result of repeated application of dinitroaniline herbicides, highly resistant and intermediately resistant biotypes of goosegrass (Eleusine indica) developed in previously wild-type populations. Three alpha-tubulin cDNA classes (designated TUA1, TUA2, and TUA3) were isolated from each biotype. Nucleotide differences between the susceptible and the resistant (R) alpha-tubulins were identified in TUA1 and TUA2. The most significant differences were missense mutations that occurred in TUA1 of the R and intermediately resistant (I) biotypes. Such mutations convert Thr-239 to Ile in the R biotype and Met-268 to Thr in the I biotype. These amino acid substitutions alter hydrophobicity; therefore, they may alter the dinitroaniline binding property of the protein. These mutations were correlated with the dinitroaniline response phenotypes (Drp). Plants homozygous for susceptibility possessed the wild-type TUA1 allele; plants homozygous for resistance possessed the mutant tua1 allele; and plants heterozygous for susceptibility possessed both wild-type and mutant alleles. Thus, we conclude that TUA1 is at the Drp locus. Using polymerase chain reaction primer-introduced restriction analysis, we demonstrated that goosegrass genomic DNA can be diagnosed for Drp alleles. Although not direct proof, these results suggest that a mutation in an alpha-tubulin gene confers resistance to dinitroanilines in goosegrass.
Yamamoto
E
E
Department of Horticulture, Clemson University, Clemson, South Carolina 29634, USA.
Zeng
L
L
Baird
W V
WV
D000483:Alleles; D000595:Amino Acid Sequence; D000814:Aniline Compounds / Q000494:pharmacology; D001483:Base Sequence; D018076:DNA, Complementary / Q000737:chemistry; D018744:DNA, Plant / Q000737:chemistry; D004351:Drug Resistance / Q000235:genetics; D002523:Edible Grain / Q000187:drug effects / Q000235:genetics*; D006540:Herbicides / Q000494:pharmacology; D008870:Microtubules / Q000187:drug effects*; D008969:Molecular Sequence Data; D009154:Mutation; D014404:Tubulin / Q000235:genetics*
D000814:Aniline Compounds; D018076:DNA, Complementary; D018744:DNA, Plant; D006540:Herbicides; D014404:Tubulin; C006852:butralin