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

Gong HY, Li Y, Fang G, Hu DH, Jin WB, Wang ZH, Li YS - PLoS ONE (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China; Engineering Research Centre for the Protection and Utilization of Bioresource in Ethnic Area of Southern China, South-Central University for Nationalities, Wuhan, China.

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.

No MeSH data available.


Related in: MedlinePlus

Subcellular localization of ICTB and FBP/SBPase protein.A, Bright field view of protoplasts. B, GFPsignals from the ICTB-GFP fusion protein. C, Merged images.D, Red chlorophyll autofluorescence used as achloroplast marker. E, GFP signals from the ICTB-RBCS-GFPfusion protein. F, Merged images. G, Redchlorophyll autofluorescence. H, GFP signals from theFBP/SBPase-RBCS-GFP fusion protein. I, Merged images, withyellow fluorescence in the merged images due to red chloroplastautofluorescence.
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pone.0140928.g002: Subcellular localization of ICTB and FBP/SBPase protein.A, Bright field view of protoplasts. B, GFPsignals from the ICTB-GFP fusion protein. C, Merged images.D, Red chlorophyll autofluorescence used as achloroplast marker. E, GFP signals from the ICTB-RBCS-GFPfusion protein. F, Merged images. G, Redchlorophyll autofluorescence. H, GFP signals from theFBP/SBPase-RBCS-GFP fusion protein. I, Merged images, withyellow fluorescence in the merged images due to red chloroplastautofluorescence.

Mentions: Successful transformation and expression of Ictb andFBP/Sbpase were achieved in rice, but it was unclearwhether the proteins were localized in functional, interacting subcellularspaces related to CO2 transport and fixation. Consequently, thein vivo subcellular localization of ICTB and FBP/SBPasewere tested by transiently expressing their fused GFP proteins in living riceprotoplasts (Fig 2). Theresults showed that ICTB was present in the cytoplasm with or without RBCSsignal peptide. In the present case, it was possible that our initial procedurewas insufficient to deliver ICTB into chloroplasts and that the finaldestination was in the cytoplasm. Because eukaryotic cells are highlycompartmentalized and the subcellular localization of a protein is intrinsic toits function [61]. Theprotein localization findings may support role for ICTB in transcellular carbondelivery to chloroplasts, as reported for aquaporins [62], which has a positiverole in accelerating carbon diffusion and improvinggm in the liquid phase (Table 1). FBP/SBPaselocalized in the chloroplast and might promote CO2 assimilation inthe transgenic lines based on our results (Table 1). These results meant that they exertedfunctions at different sites in the route of CO2 transport andassimilation respectively, thereby improving the photosynthetic efficiency.


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

Gong HY, Li Y, Fang G, Hu DH, Jin WB, Wang ZH, Li YS - PLoS ONE (2015)

Subcellular localization of ICTB and FBP/SBPase protein.A, Bright field view of protoplasts. B, GFPsignals from the ICTB-GFP fusion protein. C, Merged images.D, Red chlorophyll autofluorescence used as achloroplast marker. E, GFP signals from the ICTB-RBCS-GFPfusion protein. F, Merged images. G, Redchlorophyll autofluorescence. H, GFP signals from theFBP/SBPase-RBCS-GFP fusion protein. I, Merged images, withyellow fluorescence in the merged images due to red chloroplastautofluorescence.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4638112&req=5

pone.0140928.g002: Subcellular localization of ICTB and FBP/SBPase protein.A, Bright field view of protoplasts. B, GFPsignals from the ICTB-GFP fusion protein. C, Merged images.D, Red chlorophyll autofluorescence used as achloroplast marker. E, GFP signals from the ICTB-RBCS-GFPfusion protein. F, Merged images. G, Redchlorophyll autofluorescence. H, GFP signals from theFBP/SBPase-RBCS-GFP fusion protein. I, Merged images, withyellow fluorescence in the merged images due to red chloroplastautofluorescence.
Mentions: Successful transformation and expression of Ictb andFBP/Sbpase were achieved in rice, but it was unclearwhether the proteins were localized in functional, interacting subcellularspaces related to CO2 transport and fixation. Consequently, thein vivo subcellular localization of ICTB and FBP/SBPasewere tested by transiently expressing their fused GFP proteins in living riceprotoplasts (Fig 2). Theresults showed that ICTB was present in the cytoplasm with or without RBCSsignal peptide. In the present case, it was possible that our initial procedurewas insufficient to deliver ICTB into chloroplasts and that the finaldestination was in the cytoplasm. Because eukaryotic cells are highlycompartmentalized and the subcellular localization of a protein is intrinsic toits function [61]. Theprotein localization findings may support role for ICTB in transcellular carbondelivery to chloroplasts, as reported for aquaporins [62], which has a positiverole in accelerating carbon diffusion and improvinggm in the liquid phase (Table 1). FBP/SBPaselocalized in the chloroplast and might promote CO2 assimilation inthe transgenic lines based on our results (Table 1). These results meant that they exertedfunctions at different sites in the route of CO2 transport andassimilation respectively, thereby improving the photosynthetic efficiency.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China; Engineering Research Centre for the Protection and Utilization of Bioresource in Ethnic Area of Southern China, South-Central University for Nationalities, Wuhan, China.

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.

No MeSH data available.


Related in: MedlinePlus