Instituto de Fisiología Vegetal (Universidad Nacional de La Plata-Consejo Nacional de Investigaciones Científicas y Técnicas), La Plata, Argentina.
Plant Physiol Biochem. 2012 Aug;57:210-7. doi: 10.1016/j.plaphy.2012.05.027. Epub 2012 Jun 7.
Despite the extensive use of glyphosate, how it alters the physiology and metabolism of plants is still unclear. Photosynthesis is not regarded to be a primary inhibitory target of glyphosate, but it has been reported to be affected by this herbicide. The aim of the current research was to determine the effects of glyphosate on the light and dark reactions of photosynthesis by comparing glyphosate-susceptible and glyphosate-resistant Lolium perenne biotypes. After glyphosate treatment, accumulation of reduced carbohydrates occurred before a decrease in gas exchange. Stomatal conductance and CO(2) assimilation were reduced earlier than chlorophyll fluorescence and the amount of chlorophyll in susceptible plants. In the glyphosate-resistant biotype, stomatal conductance was the only parameter slightly affected only 5 days post-application. In susceptible plants, the initial glyphosate effects on gas exchange could be a response to a feedback regulation of photosynthesis. Since the herbicide affects actively growing tissues regardless of the inhibition of photosynthesis, the demand of assimilates decreased and consequently induced an accumulation of carbohydrates in leaves. We concluded that stomatal conductance could be a very sensitive parameter to assess both the susceptibility/resistance to glyphosate before the phytotoxic symptoms become evident.
尽管草甘膦被广泛使用，但它如何改变植物的生理和代谢仍不清楚。光合作用不被认为是草甘膦的主要抑制靶标，但据报道它会受到这种除草剂的影响。本研究的目的是通过比较对草甘膦敏感和耐受的黑麦草生物型，确定草甘膦对光合作用的光和暗反应的影响。在草甘膦处理后，在气体交换减少之前，还原碳水化合物的积累发生。与敏感植物相比，气孔导度和 CO2 同化在叶绿素荧光和叶绿素含量降低之前降低。在抗草甘膦生物型中，仅在施药后 5 天，气孔导度是唯一受到轻微影响的参数。在敏感植物中，气体交换的初始草甘膦作用可能是光合作用反馈调节的反应。由于除草剂会影响活跃生长的组织，而不管光合作用的抑制如何，因此同化产物的需求减少，从而导致叶片中碳水化合物的积累。我们得出结论，气孔导度可能是评估对草甘膦的敏感性/抗性的非常敏感的参数，在出现植物毒性症状之前。
