Effects of co-overexpression of the genes of Rubisco and transketolase on photosynthesis in rice.
Metabolome analyses have indicated an accumulation of sedoheptulose 7-phosphate in transgenic rice plants with overproduction of Rubisco (Suzuki et al. in Plant Cell Environ 35:1369-1379, 2012. doi: 10.1111/j.1365-3040.2012.02494.x ). Since Rubisco overproduction did not quantitatively enhance photosynthesis even under CO2-limited conditions, it is suspected that such an accumulation of sedoheptulose 7-phosphate hampers the improvement of photosynthetic capacity. In the present study, the gene of transketolase, which is involved in the metabolism of sedoheptulose 7-phosphate, was co-overexpressed with the Rubisco small subunit gene in rice. Rubisco and transketolase were successfully overproduced in comparison with those in wild-type plants by 35-53 and 39-84 %, respectively. These changes in the amounts of the proteins were associated with those of the mRNA levels. However, the rate of CO2assimilation under high irradiance and different [CO2] did not differ between co-overexpressed plants and wild-type plants. Thus, co-overproduction of Rubisco and transketolase did not improve photosynthesis in rice. Transketolase was probably not a limiting factor of photosynthesis as overproduction of transketolase alone by 80-94 % did not affect photosynthesis.
Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, 981-8555, Japan. ysuzuki@biochem.tohoku.ac.jp.|CREST, JST, Gobancho, Chiyoda-ku, Tokyo, 102-0076, Japan. ysuzuki@biochem.tohoku.ac.jp.|Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Iwate, 020-8550, Japan. ysuzuki@biochem.tohoku.ac.jp.
Yuji
http://orcid.org/0000-0002-8029-9385
Y
Suzuki
Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, 981-8555, Japan.
Eri
E
Kondo
Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, 981-8555, Japan.|CREST, JST, Gobancho, Chiyoda-ku, Tokyo, 102-0076, Japan.
Amane
http://orcid.org/0000-0003-2779-6275
A
Makino
D017343:Genes, Plant; D012275:Oryza / Q000201:enzymology / Q000235:genetics*; D030821:Plants, Genetically Modified; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics*; D014174:Transketolase / Q000235:genetics*
D014174:Transketolase; D012273:Ribulose-Bisphosphate Carboxylase
CO2 assimilation; Overproduction; Rice; Rubisco; Transketolase