In order to investigate the effect of large isoform of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activase (RuBPCO-A) on photosynthesis, cDNA of the enzyme (rca) was transferred to rice cultivars (Oryza sativa f. japonica cv. Nipponbare) under the control of RuBPCO small subunit gene promoter (rbcS) via Agrobacterium tumefaciens-mediated transformation. Transgenic rice plants were identified by polymerase chain reaction (PCR) and Southern and Western blot analyses. Net photosynthetic rate (PN ) values of the T1 transgenic lines 34 (T34) and 40 (T40) were 45.26 and 46.32 % higher than that of the control plants, respectively. At the same time, their carboxylation efficiency and RuBPCO initial activity, quantum yield of electron transport in photosystem 2 (ΦPS2), and steady state photochemical fluorescence quenching (qP) increased. In addition, heading time of the transgenic rice was advanced. Thus increasing the amount of large isoform of RuBPCO-A in the transgenic rice might have a stimulatory effect on both photosynthesis and plant growth. and H. R. Wu ... [et al.].
Abiotic stresses induce phosphoenolpyruvate carboxylase (PEPC) expression in C3 plants which suggests PEPC function in plant adaptation to stresses. Here, we studied the response of photosynthesis to short-term drought stress in rice seedlings overexpressing C4 PEPC from maize and millet. The transgenic lines exhibited 1.2-5.5 fold of PEPC activities than the wild type before the treatment, while 1.5-8.5 fold after five or ten days of water deficit. Net photosynthetic rate (P N) declined less during the water stress and recovered more after rewatering in the transgenic lines. These changes were accompanied with changes in the stomatal conductance (g s). The lower decrease in P N and g s resulted in significantly higher intrinsic water use efficiency in the transgenic rice lines after ten days of water withdrawal. There were no significant differences between the wild type and transgenic lines in maximum photochemical efficiency of PSII and photochemical quenching. The nonphotochemical quenching and the quantum efficiency of PSII maintained both higher in transgenic lines than those in the wild type during drought stress. This indicated that the transgenic lines could dissipate more excess energy to heat to protect PSII. Our result suggested that the increased PEPC activities in rice could alleviate the decrease of photosynthesis during short-term drought stress., Z. S. Ding, X. F. Sun, S. H. Huang, B. Y. Zhou, M. Zhao., and Obsahuje seznam literatury