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Selection of Tobacco Cell Lines Resistant to Photobleaching Herbicides
Mamoru HORIKOSHI and Takashi HIROOKA
J. Pestic. Sci.
24, 13-16 (1999)
Tobacco cell lines resistant to photobleaching herbicides were selected by subculturing tobacco calli regenerated from protoplasts in the presence of ET-62311 (4-chloro-3-[2,4-dichloro-5-(2-propenyloxy) phenyl]-5-difluoromethoxy-1-methylpyrazole), a derivative of pyraflufen-ethyl [ethyl 2-chloro-5-(4-chloro-5-difluoromethoxy-1-methylpyrazol-3-yl)-4-fluorophenoxyacetate] (formerly known as ET-751). Selected cell lines were more than 240-fold resistant than normal cells and designated as ETR-056, 245 and 253. The ET-62311 treatment induced Proto IX accumulation in ETR-056, but not in ETR-245 nor 253. Cross-resistance of resistant cell lines to herbicides with various mode of action was evaluated. Each. resistant cell line was cross-resistant to photobleaching herbicides such as pyraflufen-ethyl. In addition, ETR-056 was cross-resistant to paraquat and ETR-253 was cross-resistant to several herbicides with different modes of action. On the other hand, protoporphyrinogen oxidase (Protox) activity in ETR-245 was almost equivalent to that in normal cells, but more than 100-fold resistant to pyraflufen-ethyl. These results suggested the involvement of radical scavenger in ETR-056, multiple resistance due to a reduced uptake and/or an enhanced metabolism of the herbicides in ETR-253 and an alteration of Protox from photobleaching herbicide sensitive form to resistant one in ETR-245.
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