title: Photosynthetic characteristics and tolerance to photo-oxidation of transgenic rice expressing C(4) photosynthesis enzymes.
abstract: The photosynthetic characteristics of four transgenic rice lines over-expressing rice NADP-malic enzyme (ME), and maize phosphoenolpyruvate carboxylase (PC), pyruvate,orthophosphate dikinase (PK), and PC+PK (CK) were investigated using outdoor-grown plants. Relative to untransformed wild-type (WT) rice, PC transgenic rice exhibited high PC activity (25-fold increase) and enhanced activity of carbonic anhydrase (more than two-fold increase), while the activity of ribulose-bisphosphate carboxylase/oxygenase (Rubisco) and its kinetic property were not significantly altered. The PC transgenic plants also showed a higher light intensity for saturation of photosynthesis, higher photosynthetic CO(2) uptake rate and carboxylation efficiency, and slightly reduced CO(2) compensation point. In addition, chlorophyll a fluorescence analysis indicates that PC transgenic plants are more tolerant to photo-oxidative stress, due to a higher capacity to quench excess light energy via photochemical and non-photochemical means. Furthermore, PC and CK transgenic rice produced 22-24% more grains than WT plants. Taken together, these results suggest that expression of maize C(4) photosynthesis enzymes in rice, a C(3) plant, can improve its photosynthetic capacity with enhanced tolerance to photo-oxidation.
authors.affiliation: Jiangsu Academy of Agricultural Sciences, Institute of Agrobiological Genetics and Physiology, Nangjing, 210014, China, photosyn@public1.ptt.is.cn.
authors.forename: Demao
authors.initials: D
authors.lastname: Jiao
authors.forename: Xueqing
authors.initials: X
authors.lastname: Huang
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Chi
authors.forename: Tingyun
authors.initials: T
authors.lastname: Kuang
authors.forename: Qide
authors.initials: Q
authors.lastname: Zhang
authors.forename: Maurice S B
authors.initials: MS
authors.lastname: Ku
authors.forename: Dongha
authors.initials: D
authors.lastname: Cho