Overexpression of Medicago sativa glutamate-semialdehyde aminotransferase (GSA) gene in tobacco increased photosynthesis efficiency

Abstract

To investigate the effect of increased glutamate-semialdehyde aminotransferase (GSA) on photosynthetic capacity and growth, tobacco (Nicoliana tabacum L. Xanti) plants with increased levels of glutamate-semialdehyde aminotransferase protein were produced. This was achieved using a cassette composed of a full-length Medicago sative cDNA under the control of the cauliflower mosaic virus 35S promoter. The results revealed distinct impacts of GSA activity on photosynthesis rate and growth in GSA over expression tobacco plants. In transgenic plants with increased GSA activity, an increase in soluble and insoluble sugars accumulation was evident. Total biomass, leaf area, plant height and internode 3-4 were increased in GSA sense plants, compared with equivalent wild-type tobacco plants. Moreover, transgenic tobacco plants with increased GSA activity exhibit higher levels of 5-aminolevulinic acid (ALA) accumulation and increased in content of chlorophyll and carotenoids pigments. Collectively, our data suggest that higher level of GSA activity gives an advantage to photosynthesis, growth in tobacco plants. This work also provides a case study that an individual enzyme in the biosynthesis of chlorophyll pathway may serve as a useful target for genetic engineering to improve photosynthesis and growth in plants.\n\nHighlightOverexpression of glutamate-semialdehyde aminotransferase (GSA) increase photosynthetic capacity, growth in tobacco.