Overexpression of Brassica napus cytosolic fructose-1,6-bisphosphatase and sedoheptulose-1,7-bisphosphatase genes significantly enhanced tobacco growth and biomass

Elevated activities of cytosolic fructose-1,6-bisphosphatase (cyFBPase) and sedoheptulose-1,7-bisphosphatase (SBPase) are associated with higher yields in plants. In this study, the expression levels of the cyFBPase and SBPase genes were increased by overexpressing rape (Brassica napus) cDNA in tobacco (Nicotiana tabacum) plants. The transgenic plants coexpressing cyFBPase and SBPase (TpFS), or expressing single cyFBPase (TpF) or SBPase (TpS) had 1.77-, 1.55-, 1.23-fold cyFBPase and 1.45-, 1.12-, 1.36-fold SBPase activities as compared to the wild-type (WT), respectively. Photosynthesis rates of TpF, TpS and TpFS increased 4, 20 and 25% compared with WT plants. The SBPase and cyFBPase positively regulated each other and functioned synergistically in transgenic tobacco plants. In addition, the sucrose contents of the three transgenic plants were higher than that of WT plants. The starch accumulation of the TpFS and TpS plants was improved by 53 and 37%, but slightly decreased in TpF plants. Moreover, the transgenic tobacco plants harbouring SBPase and/or cyFBPase genes showed improvements in their growth, biomass, dry weight, plant height, stem diameter, leaf size, flower number, and pod weight. In conclusion, co-expression of SBPase and cyFBPase may pave a new way for improving crop yield in agricultural applications.

Automated summary

Elevated expression levels of cyFBPase and SBPase genes positively regulated each other and had synergistic effects on photosynthesis rates and growth traits of transgenic tobacco plants. Transgenic plants overexpressing cyFBPase and/or SBPase genes showed improvements in sucrose and starch contents.