Relationship between safening activity of dymron and fenclorim to pretilachlor and glutathione S-transferase activity in rice |
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| Authors: | FAN DENG YUJI YAMADA KENJI USUI |
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| Institution: | Institute of Applied Biochemistry, University of Tsukuba and; SDS Biotech K. K., Tsukuba Technology Center, Tsukuba, lbaraki, Japan |
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| Abstract: | Dymron 1‐(α,α‐dimethybenzyl)‐3‐(p‐tolyl)urea] and fenclorim (4,6‐dichloro‐2‐phenylpyrimidine) were found to exhibit a safening activity on the growth of rice (Oryza sativa L.) seedlings against pretilachlor 2‐chloro‐2′,6′diethyl‐N‐(2‐propoxyethyl)acetanilide] injury. By pretilachlor treatment at 10–6 and 10–5 mol L–1, the elongation of the third leaves of rice seedlings was reduced by approximately 20 and 40%, and that of the fourth leaves was reduced by approximately 40 and 80%, respectively. Upon the treatment of dymron at 3 × 10–6 and 10–5 mol L–1 in combination with pretilachlor, the growth inhibition was half alleviated in the third leaves, and the length of the fourth leaves was almost recovered from 10–6 mol L‐1 pretilachlor injury, and was 20–25% recovered from 10–5 mol L–1 pretilachlor injury. Upon the treatment of fenclorim at 3 × 10–6 and 10–5 mol L–1 in combination with pretilachlor, the growth inhibition of rice seedlings was almost alleviated in both the third and the fourth leaves. This result indicated that dymron and fenclorim showed almost the same safening effect on the fourth leaf growth against 10–6 mol L‐1 pretilachlor injury, although fenclorim showed higher effects at higher concentrations of pretilachlor. Glutathione S‐transferase (GST) activities in rice seedlings were investigated after being treated with a herbicide and safener. By pretilachlor treatment at 10–6 and 10–5 mol L–1, the GST activity was approximately 32 and 72% increased in roots, respectively, and a little increased (7–13%) in shoots of two‐leaf‐stage rice seedlings. By dymron treatment at 3 × 10–6?10–5 mol L–1, the GST activity was 2–30% increased in roots, but was not increased in shoots. By their combination treatment, the GST activity was almost the same or less than that by treatment with pretilachlor alone. In contrast, by fenclorim treatment alone, the GST activity was 43–52 and 33–45% increased in roots and shoots of rice seedlings, respectively. By the combination treatment of pretilachlor and fenclorim, the GST activity was increased 73–126% in shoots and 101–139% in roots, and was much more increased in both shoots and roots compared with treatment of pretilachlor or fenclorim alone. It was found that dymron showed less effect in increasing the GST activity than fenclorim. It is also suggested that dymron did not increase the GST activity in shoots but did increase it slightly in roots, and showed almost no effect on GST increase by pretilachlor in shoots, or rather reduced the increase in roots. From the above results, fenclorim and dymron may have different mechanisms of safening effects on the protection of rice seedlings against pretilachlor injury. |
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| Keywords: | dymron fenclorim glutathione S-transferase pretilachlor rice |
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