Altered photosynthesis, flowering, and fruiting in transgenic tomato plants that have an increased capacity for sucrose synthesis

✍ Scribed by Barry J. Micallef; Kirk A. Haskins; Peter J. Vanderveer; Kwang-Soo Roh; Christine K. Shewmaker; Thomas D. Sharkey

• Book ID: 104661062
• Publisher: Springer-Verlag
• Year: 1995
• Tongue: English
• Weight: 957 KB
• Volume: 196
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00201392

✦ Synopsis

Photosynthesis, leaf assimilate partitioning, flowering, and fruiting were examined in two lines of Lycopersicon esculentum Mill. transformed with a gene coding for sucrose-phosphate synthase (SPS) (EC 2.3.1.14) from Zea mays L. expressed from a tobacco ribulose-l,5-bisphosphate carboxylase/oxygenase (Rubisco) small subunit promoter. Plants were grown at either 35 or 65Pa CO 2 and high light (1000gmol photons.m-2.s-1). Limiting and maximum SPS activities were significantly greater (up to 12 times) in the leaves of SPS-transformed lines for all treatments. Partitioning of carbon into sucrose increased 50% for the SPS transformants. Intact leaves of the control lines exhibited CO2-insensitivity of photosynthesis at high CO2 levels, whereas the SPS transformants did not exhibit CO2-insensitivity. The O2-sensitivity of photosynthesis was also greater for the SPS-transformed lines compared to the untransformed control when measured at 65 Pa CO 2. These data indicate that the SPS transformants had a reduced limitation on photosynthesis imposed by endproduct synthesis. Growth at 65 Pa CO 2 resulted in reduced photosynthetic capacity for control lines but not for SPS-transformed lines. When grown at 65 Pa CO2, SPS transformed lines had a 20% greater photosynthetic rate than controls when measured at 65 Pa COz and a 35% greater rate when measured at 105 Pa CO 2. Photosynthetic rates were not different between lines when grown at 35 Pa CO z. The time to 50% blossoming was reduced and the total number of inflorescences was significantly greater for the SPS transformants when grown