Functional analysis of the role of tomato (Solanum lycopersicum L.) fruit photosynthesis in metabolism and development

• Applicant: Dr. Anna Lytovchenko
• Subject Area: Plant Physiology
• Term: from 2006 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 35285392

Particular attention in the project is paid to the effect that altering fruit photosynthesis has on aspects of fruit growth, metabolism and ripening. To this end transgenic tomato plants, under the control of a green fruit specific promoter, exhibiting independent antisense inhibition of the small subunit of Rubisco, Phosphoenolpyruvate carboxylase (PEPC) and Glutamate-1-semialdehyde aminotransferase (GSA), as well as overexpression of the latter enzyme, were generated.Results to date have revealed that overexpression of GSA and antisense inhibition of PEPC had little effect on green fruit performance or ripening in general, in particular on gas-exchange and chlorophyll fluorescence parameters. There were slight decreases in starch and several organic acid contents in plants with lower PEPC activity, and increases in hexose-phosphates in transgenic fruits overexpressing GSA.In contrast, antisense inhibition of GSA in fruits led to chlorophyll-deficient fruit phenotype and had distinct effect on fruit assimilation rate and chlorophyll quantum yield. Fruits were characterised by drastic reduction in chlorophyll a (up to 90%) and carotenoids content. However, first observations did not revealed a correlation between the decreased chlorophyll content and consequently compromised photosynthetic performance with ripening behaviour of the fruits. This and other aspects of fruit metabolism remain to be studied in detail in forthcoming experiments including application of a broad range of physiological, molecular biological and biochemical (including metabolite profiling by gas chromatography- and liquid chromatography – mass spectrometry and flux analysis) methods.

• DFG Programme: Research Grants
• Participating Persons: Privatdozentin Dr. Ljudmilla Borisjuk; Professor Dr. Bernhard Grimm