Transgenic Rice Expressing Ictb and FBP/Sbpase Derived from Cyanobacteria Exhibits Enhanced Photosynthesis and Mesophyll Conductance to CO2

Abstract

To find a way to promote the rate of carbon flux and further improve the photosynthetic rate in rice, two CO2-transporting and fixing relevant genes, Ictb and FBP/Sbpase, which were derived from cyanobacteria with the 35SCaMV promotor in the respective constructs, were transformed into rice. Three homologous transgenic groups with Ictb, FBP/Sbpase and the two genes combined were constructed in parallel, and the functional effects of these two genes were investigated by physiological, biochemical and leaf anatomy analyses. The results indicated that the mesophyll conductance and net photosynthetic rate were higher at approximately 10.5–36.8% and 13.5–34.6%, respectively, in the three groups but without any changes in leaf anatomy structure compared with wild type. Other physiological and biochemical parameters increased with the same trend in the three groups, which showed that the effect of FBP/SBPase on improving photosynthetic capacity was better than that of ICTB and that there was an additive effect in ICTB+FBP/SBPase. ICTB localized in the cytoplasm, whereas FBP/SBPase was successfully transported to the chloroplast. The two genes might show a synergistic interaction to promote carbon flow and the assimilation rate as a whole. The multigene transformation engineering and its potential utility for improving the photosynthetic capacity and yield in rice were discussed.

Simultaneous stimulation of RuBP regeneration and electron transport increases productivity and water use efficiency under field conditions

“…Additionally, in field studies we demonstrate that plants with simultaneous stimulation of electron transport and of RuBP regeneration had increased iWUE with an increase in biomass.Under glasshouse conditions, increases in photosynthesis were observed in all of the transgenic plants analysed here and these were found to be consistently correlated with increases in biomass. Although increases in photosynthesis and biomass have been reported for plants with stimulation of RuBP regeneration in both model2,3,6,7,34 and crop26,24 species; and electron transport in Arabidopsis and tobacco[28][29][30] , the data presented here provides the first report of increased photosynthesis and biomass by the simultaneous stimulation of electron transport and RuBP regeneration. Increases in A were observed under glasshouse conditions in the leaves of all of the different transgenic tobacco plants and in both of the tobacco cultivars (cv.…”

“…Previous research has shown that taking a multi-gene approach to increase the levels of more than one enzyme or protein simultaneously can result in a cumulative increase in photosynthesis and biomass yield 6,7,34 . Building on this approach, the work in this paper aims to test the hypothesis that combining an increase in the activity of a CB cycle enzyme, specifically enhancing RuBP regeneration, together with stimulation of the electron transport chain can boost photosynthesis and yield above that observed when these processes are targeted individually.…”

The Integration of Algal Carbon Concentration Mechanism Components into Tobacco Chloroplasts Increases Photosynthetic Efficiency and Biomass

“…However, they could barely survive at ambient levels of atmospheric CO 2 thus showing that other components of the cyanobacterial CCM were necessary for efficient CO 2 fixation in C 3 plants. In contrast, transfer of the cyanobacterial inorganic carbon transporter B (IctB) enhanced biomass accumulation in a variety of plant species, including A. thaliana , tobacco, rice, and soybean . Transfer of the C. reinhardtii putative inorganic carbon transporters LCIA and HLA3 as GFP fusions into A. thaliana resulted in growth comparable with that of wild‐type plants …”

Demand for food as driver for plant sink development

“…Here, photosynthetic performance was also increased. However, of the three parameters determining grain yield in rice, i.e., tiller number, filled grains per panicle and grain weight, only tiller number was increased in the double transformant (Gong et al, 2015).…”