Hongju Ma1,2, Huan Lu2, Heping Han2, Qin Yu2, Stephen Powles2. 1. Department of Plant Protection, College of Plant Sciences & Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei, China. 2. Australian Herbicide Resistance Initiative (AHRI), School of Agriculture and Environment, University of Western Australia, WA, 6009, Australia.
Abstract
BACKGROUND: The PSII-inhibiting herbicides are important for Australian farmers to control Lolium rigidum Gaud. and other weed species in trazine tolerant (TT)-canola fields. A L. rigidum population (R) collected from a TT-canola field from Western Australia showed multiple resistance to photosystem II (PSII), acetyl-coenzyme A carboxylase (ACCase) and acetolactate synthase (ALS) inhibitors. The mechanisms of multiple resistance in this R population were determined. RESULTS: The R population showed a low-level (about 3.0-fold) resistance to the PSII- inhibiting herbicides metribuzin and atrazine. Sequencing of the psbA gene revealed no differences between the R and susceptible (S) sequences. [14 C]-metribuzin experiments found no significant difference in metribuzin foliar uptake and translocation between the R and S plants. However, [14 C]-metribuzin metabolism in R plants was 2.3-fold greater than in S plants. The cytochrome P450 monooxygenase inhibitor piperonyl butoxide (PBO) enhanced plant mortality response to metribuzin and atrazine in both R and S populations. In addition, multiple resistance to ALS and ACCase inhibitors are due to known resistance mutations in ALS and ACCase genes. CONCLUSION: The results demonstrate that enhanced metribuzin metabolism likely involving cytochrome P450 monooxygenase contributes to metribuzin resistance in L. rigidum. This is the first report of metabolic resistance to the PSII-inhibiting herbicide metribuzin in Australian L. rigidum. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
BACKGROUND: The PSII-inhibiting herbicides are important for Australian farmers to control Lolium rigidum Gaud. and other weed species in trazine tolerant (TT)-canola fields. A L. rigidum population (R) collected from a TT-canola field from Western Australia showed multiple resistance to photosystem II (PSII), acetyl-coenzyme A carboxylase (ACCase) and acetolactate synthase (ALS) inhibitors. The mechanisms of multiple resistance in this R population were determined. RESULTS: The R population showed a low-level (about 3.0-fold) resistance to the PSII- inhibiting herbicides metribuzin and atrazine. Sequencing of the psbA gene revealed no differences between the R and susceptible (S) sequences. [14 C]-metribuzin experiments found no significant difference in metribuzin foliar uptake and translocation between the R and S plants. However, [14 C]-metribuzin metabolism in R plants was 2.3-fold greater than in S plants. The cytochrome P450 monooxygenase inhibitor piperonyl butoxide (PBO) enhanced plant mortality response to metribuzin and atrazine in both R and S populations. In addition, multiple resistance to ALS and ACCase inhibitors are due to known resistance mutations in ALS and ACCase genes. CONCLUSION: The results demonstrate that enhanced metribuzin metabolism likely involving cytochrome P450 monooxygenase contributes to metribuzin resistance in L. rigidum. This is the first report of metabolic resistance to the PSII-inhibiting herbicide metribuzin in Australian L. rigidum. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Authors: Andréia K Suzukawa; Lucas K Bobadilla; Carol Mallory-Smith; Caio A C G Brunharo Journal: Front Plant Sci Date: 2021-01-22 Impact factor: 5.753