黄瓜幼苗Rubisco与Rubisco活化酶对弱光的响应

hanges of photosynthetic rate (Pn), activities and gene expression of Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and Rubisco activase (RCA) in 'Jinyou 3' cucumber seedlings under optimal temperature and low light intensity (LL: 25℃/18℃，100 μmolom-2os-1), suboptimal temperature and low light intensity (ST+LL: 18℃/12℃，100μmolom-2os-1) were investigated. The result showed that LL and ST+LL treatments all led to a remarkable decrease in leaf area and dry matter. Their Pn, Rubisco activity, rbcL and rbcS expression, RCA activity and CsRCA expression declined by a big margin on early treating days. 5~7 days later, the Pn, activities and gene expression of Rubisco and RCA were constant in LL treatment seedlings, whereas ascended slowly in ST+LL treatment seedlings. These data suggested that photosynthetic apparatus in cucumber seedlings had adaptation mechanism to low light intensity and suboptimal temperature. The activities and gene expression of Rubisco and RCA showed a similar response to suboptimal temperature and low light intensity with Pn. This indicated that the decline in activities and gene expression of Rubisco and RCA in cucumber seedlings under suboptimal temperature and low light intensity were important reasons wihich led to decrease in Pn.