Knowles F C, Benson A A
Marine Biology Research Division, A-002, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093.
Plant Physiol. 1983 Feb;71(2):235-40. doi: 10.1104/pp.71.2.235.
Johnsongrass (Sorghum halepense (L.) Pers.) is sensitive to methanearsonate, foliar application resulting in a topkill. Investigation of the pattern of photosynthesis by radioautography revealed an accumulation of malate in methanearsonate-treated leaves. Accumulation of malate was attributed to an inhibition of NADP(+)-malic enzyme which was found to be sensitive to sulfhydryl group reagents including arsenosomethane, CH(3)AsO. Methanearsonate was found to act as an oxidant in the Hill reaction using spinach chloroplasts, the photoproduct being a sulfhydryl group reagent.These results suggest that methanearsonate inhibits CO(2) release from malate in bundle sheath cells, depriving the plant of its source of carbon for sucrose production. The mechanism of inhibition of enzymes sensitive to sulfhydryl group reagents by arsenosomethane is addressed.
约翰逊草(Sorghum halepense (L.) Pers.)对甲胂酸敏感,叶面喷施会导致植株顶部死亡。通过放射自显影对光合作用模式的研究表明,经甲胂酸处理的叶片中苹果酸会积累。苹果酸的积累归因于NADP(+)-苹果酸酶受到抑制,该酶被发现对包括甲胂甲烷(CH(3)AsO)在内的巯基试剂敏感。研究发现,甲胂酸在使用菠菜叶绿体的希尔反应中充当氧化剂,光产物是一种巯基试剂。这些结果表明,甲胂酸抑制了维管束鞘细胞中苹果酸释放二氧化碳,从而使植物失去了用于蔗糖生产的碳源。文中探讨了甲胂甲烷对巯基试剂敏感的酶的抑制机制。