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Identification of Triazine-Resistant Vulpia bromoides

Published online by Cambridge University Press:  20 January 2017

Michael B. Ashworth*
Affiliation:
Australian Herbicide Resistance Initiative, School of Plant Biology, The University of Western Australia, Perth, Western Australia 6009, Australia Department of Agriculture and Environment, School of Science, Curtin University, Perth, Western Australia, 6845, Australia
Heping Han
Affiliation:
Australian Herbicide Resistance Initiative, School of Plant Biology, The University of Western Australia, Perth, Western Australia 6009, Australia
Garren Knell
Affiliation:
Consult-Ag, P.O. Box 398, Narrogin, Western Australia, 6312, Australia
Stephen B. Powles
Affiliation:
Australian Herbicide Resistance Initiative, School of Plant Biology, The University of Western Australia, Perth, Western Australia 6009, Australia
*
Corresponding author's E-mail: m.ashworth@curtin.edu.au.
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Abstract

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In Australia, triazine herbicides have routinely controlled the Vulpia species (Vulpia bromoides, Vulpia myuros, and Vulpia fasciculata; collectively referred to as silvergrass). However, a simazine-resistant silvergrass biotype, collected from Pingelly in the Western Australian grain belt in 2014, has been confirmed. Compared to the pooled mortality of three simazine-susceptible silvergrass populations (S1, S2, and S3), the simazine-resistant Pingelly population was > 594-fold resistant at the LD50 level. Dose-response screening of the simazine-selected progeny (> 800 g ai simazine ha−1) demonstrated that the simazine resistance mechanism was heritable. Sequencing of the chloroplast psbA gene revealed the resistant population is homozygous for a serine 264 to glycine mutation, which confers a high-level triazine resistance. As expected this Ser-264-Gly mutation conferred resistance to atrazine and metribuzin, but not the phenyl-urea diuron. This is the first published report confirming field-evolved triazine resistance in a Vulpia population.

En Australia, los herbicidas triazine han controlado rutinariamente especies del género Vulpia (Vulpia bromoides, Vulpia myuros, y Vulpia fasciculata; colectivamente referidas como silvergrass). Sin embargo se ha confirmado un biotipo de silvergrass resistente a simazine, el cual fue colectado en Pingelly, en la faja de granos del Oeste de Australia, en 2014. Al compararse con la mortalidad promediada de tres poblaciones de silvergrass susceptibles a simazine (S1, S2, y S3), la población Pingelly resistente a simazine fue > 594 veces más resistente según el nivel de LD50. Una evaluación de respuesta a dosis de la progenie seleccionada con simazine (> 800 g ai simazine ha−1) demostró que el mecanismo de resistencia a simazine fue heredable. La secuenciación del gen psbA del cloroplasto reveló que la población resistente es homocigota para la mutación serine 263 a glycine, la cual confiere un alto nivel de resistencia a triazine. Como se esperaba, esta mutación Ser-264-Gly confirió resistencia a atrazine y metribuzin, pero no a diuron, un herbicida phenyl-urea. Este es el primer reporte publicado confirmando la resistencia a triazine evolucionada en campo en una población de Vulpia.

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Type
Research Article
Copyright
Copyright © Weed Science Society of America