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NOTES ABOUT THIS BIOTYPE
Acetolactate synthase-inhibitor resistance in Monochoria vaginalis (Burm. f.) C. Presl from Indonesia.
Author(s) : Widianto, R. ; Kurniadie, D. ; Widayat, D. ; Umiyati, U. ; Nasahi, C. ; Sari, S. ; Juraimi, A. S. ; Kato-Noguchi, H.
Author Affiliation : Department of Agronomy, Faculty of Agriculture, Universitas Padjadjaran, Jl. Raya, Bandung Sumedang Km 21, Jatinangor, Sumedang 45363, Jawa Barat, Indonesia.
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Journal article : Plants 2022 Vol.11 No.3 ref.33
Abstract : Monochoria vaginalis (Burm. f.) C. Presl, belonging to the family Pontederiaceae, is an aquatic herbaceous plant, native to temperate and tropical Asia. The species often occurs in paddy fields as a noxious weed in East Asia, and in the USA, and causes a significant reduction in rice production. The objective of the present research was the evaluation of the resistance levels of M. vaginalis against three chemical groups of acetolactate synthase (ALS)-inhibitor herbicides and other two different groups of herbicides, and the investigation of the mutations in the ALS gene of the resistant biotype of M. vaginalis. Herbicide dose-response experiments showed that the resistant biotype of M. vaginalis was highly resistant to bensulfuron-methyl, moderately resistant to bispyribac-sodium, had low resistance to penoxsulam and 2,4-D dimethyl ammonium, and was susceptible to sulfentrazone. The nucleotide sequences of the ALS gene of resistant and susceptible biotypes showed 14 base substitutions, which caused two amino acid substitutions: Val-143-Ile and Val-148-Ile. It is the first report of the substitutions of amino acids Val-143-Ile and Val-148-Ile in ALS protein. Those mutations may give different resistance spectra against three ALS-inhibitor herbicides: bensulfuron-methyl, bispyribac-sodium, and penoxsulam. Further research is needed to elucidate the molecular basis of target-site resistance mechanisms such as the transformation of the ALS gene of M. vaginalis. It is also necessary to evaluate herbicide mixtures and/or the rotation of herbicide sites of action to control the resistant biotype of M. vaginalis.
ISSN : 2223-7747
DOI : 10.3390/plants11030400
CONTRIBUTING WEED SCIENTISTS
The evolution of herbicide resistance in weeds is an example of parallel evolution, throughwhich genes encoding herbicide target proteins are repeatedly represented as evolutionarytargets. The number of herbicide target-site genes differs among species, and little is knownregarding the effects of duplicate gene copies on the evolution of herbicide resistance.
We investigated the evolution of herbicide resistance in Monochoria vaginalis, which car-ries ﬁve copies of sulfonylurea target-site acetolactate synthase (ALS) genes. Suspected resis-tant populations collected across Japan were investigated for herbicide sensitivity and ALSgene sequences, followed by functional characterization and ALS gene expression analysis.
We identiﬁed over 60 resistant populations, all of which carried resistance-conferring aminoacid substitutions exclusively in MvALS1 or MvALS3. All MvALS4 alleles carried a loss-of-function mutation. Although the enzymatic properties of ALS encoded by these genes werenot markedly different, the expression of MvALS1 and MvALS3 was prominently higheramong all ALS genes.
The higher expression of MvALS1 and MvALS3 is the driving force of the biased represen-tation of genes during the evolution of herbicide resistance in M. vaginalis. Our ﬁndings high-light that gene expression is a key factor in creating evolutionary hotspots