Omokawa H, Wu J, Hatzios KK
Laboratory for Molecular Biology of Plant Stress, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, 24061-0330
Pestic Biochem Physiol. 1996 May;55(1):54-63. doi: 10.1006/pest.1996.0035.
The comparative efficacy and mechanism of action of the herbicide dymuron and its two optically active monomethyl analogues, (R)-1-(alpha-methylbenzyl)-3-(p-tolylurea) (R-MBTU) and S-MBTU, as safeners of rice against injury from bensulfuron-methyl were investigated. Bioassays using etiolated seedlings of rice (Oryza sativa L., cv. Lemont), grown either in agar or in liquid media containing bensulfuron-methyl, showed that this sulfonylurea herbicide is a potent inhibitor of rice root growth (I50 = 120 nM). Similar studies with the herbicide dymuron and its two optically active monomethyl analogues (R-MTBU and S-MTBU) showed that at 10 μM, dymuron and R-MBTU reduced rice root length by 25 and 17%, respectively, whereas S-MBTU had no effect on root growth of Lemont rice. Combined treatments with bensulfuron-methyl and dymuron or each of its two analogues confirmed that S-MTBU is an excellent safener of rice against bensulfuron-methyl, far more effective than either dymuron or R-MTBU. The protective action of S-MTBU appeared to result mainly from a drastic reduction in the uptake of bensulfuron-methyl by safened rice seedlings. Dymuron and R-MTBU reduced also the uptake of bensulfuron-methyl by rice seedlings, but to a lesser extent than S-MTBU. Quantitative changes in the metabolism of bensulfuron-methyl by safened rice seedlings were also observed, but did not appear to support the involvement of enhanced herbicide metabolism in the safening action of S-MBTU, R-MBTU, and dymuron. The major metabolites of bensulfuron-methyl detected in both safened and unsafened rice seedlings were tentatively identified as methyl-(4-hydroxy-6-methoxypyrimidin-2-yl-carbamoylsulfamoyl)-o-toluate; methyl-(aminosulfonyl)-o-toluate; and 1H-2,3-benzothiazin-4-(3H)-one-2,2-dioxide.
研究了除草剂敌草隆及其两种旋光性单甲基类似物，即（R）-1-（α-甲基苄基）-3-（对甲苯基脲）（R-MBTU）和S-MBTU，作为水稻抗苄嘧磺隆伤害安全剂的比较功效及作用机制。使用在含苄嘧磺隆的琼脂或液体培养基中生长的水稻（Oryza sativa L.，品种Lemont）黄化幼苗进行的生物测定表明，这种磺酰脲类除草剂是水稻根系生长的强效抑制剂（I50 = 120 nM）。对敌草隆及其两种旋光性单甲基类似物（R-MTBU和S-MTBU）进行的类似研究表明，在10 μM时，敌草隆和R-MBTU分别使水稻根长减少25%和17%，而S-MBTU对Lemont水稻的根系生长没有影响。苄嘧磺隆与敌草隆或其两种类似物之一的联合处理证实，S-MTBU是水稻抗苄嘧磺隆的优良安全剂，远比敌草隆或R-MTBU有效。S-MTBU的保护作用似乎主要源于经安全处理的水稻幼苗对苄嘧磺隆的吸收大幅减少。敌草隆和R-MTBU也降低了水稻幼苗对苄嘧磺隆的吸收，但程度低于S-MTBU。还观察到经安全处理的水稻幼苗对苄嘧磺隆代谢的定量变化，但似乎不支持增强除草剂代谢参与S-MBTU、R-MBTU和敌草隆的安全作用。在经安全处理和未经安全处理的水稻幼苗中检测到的苄嘧磺隆主要代谢物初步鉴定为甲基-（4-羟基-6-甲氧基嘧啶-2-基-氨基甲酰基磺酰胺基）-邻甲苯酸酯；甲基-（氨基磺酰基）-邻甲苯酸酯；以及1H-2,3-苯并噻嗪-4-（3H）-酮-2,2-二氧化物。
