Metabolic Control of Anaerobic Glycolysis (Overexpression of Lactate Dehydrogenase in Transgenic Tomato Roots Supports the Davies-Roberts Hypothesis and Points to a Critical Role for Lactate Secretion.

摘要: Roots of all plants examined so far have the potential for both ethanol and lactate fermentation. A short burst fermentation usually occurs when plant tissues are transferred from normoxic to anoxic conditions. According Davies-Roberts hypothesis, consequent pH drop initiates blocks further production by inhibiting dehydrogenase (LDH). However, role LDH in this control mechanism is still a matter debate. To perturb system defined way, barley cDNA under cauliflower mosaic virus 35S promoter was introduced into tomato (Lycopersicon esculentum Mill. cv VFMT) using Agrobacterium rhizogenes. The transgenic root clones expressed up 50 times activity controls. fermentative metabolism these compared roots grown previously conditions or given 3-d hypoxic pretreatment. During transition normoxia anoxia, accumulation no faster more extensive than Similarly, during prolonged anoxia flux 14C [U-14C] glucose not modified expression transgene. roots, pretreatment increased promoted export medium. These results show that has very low coefficient fermentation, consistent with hypothesis. Moreover, they suggest secretion exerts major over long-term glycolysis vivo.