Investigation of clomazone‐tolerance mechanism in a long‐grain cultivar of rice

Abstract

BACKGROUND Clomazone is a potent herbicide for controlling weeds that have evolved resistance to other herbicides due to its unique mode of action. Clomazone is used in rice cultivation, but is limited to long‐grain cultivars because other cultivars are highly sensitive to it. In this study, we investigated the mechanism of clomazone tolerance in a long‐grain cultivar. RESULTS The long‐grain cultivar Kasalath tolerated approximately five‐fold higher doses of clomazone compared to two short‐grain cultivars, Nipponbare and Koshihikari. While Arabidopsis thaliana transformed with a rice cytochrome P450, CYP81A6, showed resistance to clomazone, the cyp81a6 knockout Kasalath was unchanged in its clomazone sensitivity. The inheritance of clomazone sensitivity in the F1 and F2 of Kasalath and Nipponbare indicated the involvement of multiple loci for clomazone tolerance. Four chromosome segment substitution lines of Nipponbare/Kasalath and Koshihikari/Kasalath exhibited partial tolerance to clomazone. The overlapping DNA region among the four lines is on chromosome 5 within 11.5 Mb. CONCLUSION Multiple loci are involved in clomazone tolerance in Kasalath, one of which is located on chromosome 5. This information will help develop short‐grain cultivars tolerant to clomazone. © 2021 Society of Chemical Industry

Comparison of herbicide specificity of CYP81A cytochrome P450s from rice and a multiple‐herbicide resistant weed, Echinochloa phyllopogon

“…Whereas the growth of WT A. thaliana was suppressed at 1 nmol L −1 BSM, A. thaliana expressing OsCYP81A6 and EpCYP81A s were almost unaffected at 1000 nmol L −1 (Fig. 2(A)), which is consistent with the findings of previous studies, 18–20,24 and could grow at 3000 nmol L −1 (Fig. 2(B)).…”

“…Herbicide sensitivities of wild‐type (WT) and transgenic A. thaliana plants were assessed by growth on Murashige and Skoog solid medium containing varying concentrations of BSM and PPS based on procedures in previous publications 16,18–20 . Previously developed transgenic A. thaliana lines, OsCYP81A6 line81A6#20, 24 EpCYP81A12 line#21, 18 and EpCYP81A21 line#6, 18 and the ecotype Colombia‐0, which served as the WT control, were used in the present study. In brief, surface‐sterilized seeds were placed on solid Murashige and Skoog medium in Petri dishes supplemented with PPS or BSM.…”

“…Herbicide sensitivities of wild-type (WT) and transgenic A. thaliana plants were assessed by growth on Murashige and Skoog solid medium containing varying concentrations of BSM and PPS based on procedures in previous publications. 16,[18][19][20] Previously developed transgenic A. thaliana lines, OsCYP81A6 line81A6#20, 24 www.soci.org W Ha et al…”

Heterologous expression of CYP81A6 from rice (Oryza sativa) in Escherichia coli and structural analyses of bensulfuron‐methyl metabolites

“…How to cite this article: Yamaguchi, T., Matsumura, K., Iwakami, S., Sunohara, Y., & Matsumoto, H. (2021). Heterologous expression of CYP81A6 from rice (Oryza sativa) in Escherichia coli and structural analyses of bensulfuron-methyl metabolites.…”

“…P450s, localized in the rice microsome fraction, catalyze the O ‐demethylation of BSM to form non‐toxic O ‐demethylated BSM (Deng & Hatzios, 2002). In addition, knockdown or disrupted mutants of rice CYP81A6 , a P450 gene, show high sensitivity to BSM (Guo et al, 2021; Pan et al, 2006; Saika et al, 2014). Thus, CYP81A6 is presumably responsible for the O ‐demethylation of BSM.…”