Towards efficient photosynthesis: overexpression of Zea mays phosphoenolpyruvate carboxylase in Arabidopsis thaliana

Abstract

Plants with C4 photosynthesis are efficient in carbon assimilation and have an advantage over C3 photosynthesis. In C4 photosynthesis, the primary CO fixation is catalyzed by phosphoenolpyruvate carboxylase (PEPC). Here, we show that overexpression of Zea mays PEPC cDNA, under the control of S promoter, in Arabidopsis thaliana resulted in ~7-10 fold higher protein abundance and ~7-10 fold increase in PEPC activity in the transgenic lines than that in the vector control. We suggest that overexpression of PEPC played an anaplerotic role to increase the supply of 4-carbon carboxylic acids, which provided carbon skeletons for increased amino acid and protein synthesis. Higher protein content must have been responsible for increased metabolic processes including chlorophyll biosynthesis, photosynthesis, and respiration. Consequently, the PEPC-overexpressed transgenic plants had higher chlorophyll content, enhanced electron transport rate (ETR), lower non-photochemical quenching (NPQ) of chlorophyll a fluorescence, and a higher performance index (PI) than the vector control. Consistent with these observations, the rate of CO assimilation, the starch content, and the dry weight of PEPC-overexpressed plants increased by 14-18 %, 10-18 %, and 6.5-16 %, respectively. Significantly, transgenics were tolerant to salt stress as they had increased ability to synthesize amino acids, including the osmolyte proline. NaCl (150 mM)-treated transgenic plants had higher variable to maximum Chl a fluorescence (F /F) ratio, higher PI, higher ETR, and lower NPQ than the salt-treated vector controls. These results suggest that expression of C4 photosynthesis enzyme(s) in a C3 plant can improve its photosynthetic capacity with enhanced tolerance to salinity stress.

Alleviation of Nitrogen and Sulfur Deficiency and Enhancement of Photosynthesis in Arabidopsis thaliana by Overexpression of Uroporphyrinogen III Methyltransferase (UPM1)

“…Similarly, transgenic tobacco plants expressing a bifunctional cyanobacterial fructose-1,6 /sedoheptulose-1,7-bisphosphatase in chloroplasts had higher photosynthesis and dry matter production (Miyagawa et al, 2001 ). In our laboratory, Kandoi et al have previously shown that the overexpression of maize phosphoenolpyruvate carboxylase (PEPC) in A. thaliana resulted in increased photosynthesis and biomass (Kandoi et al, 2016 ). PEPC in C4 carbon metabolism also plays a crucial role in the nitrogen assimilation (Shi et al, 2015 ).…”

Exploiting the Genetic Diversity of Maize Using a Combined Metabolomic, Enzyme Activity Profiling, and Metabolic Modeling Approach to Link Leaf Physiology to Kernel Yield

“…It has also been shown that in C 3 cereals the enzyme NADH-GOGAT is important for yield performance (Tamura et al, 2011). The C 4 photosynthetic pathway is considered a key biotechnological target for crop improvement (Covshoff and Hibberd, 2012;Kandoi et al 2016).…”

Phosphoenolpyruvate carboxylase (PEPC) and PEPC-kinase (PEPC-k) isoenzymes in Arabidopsis thaliana: role in control and abiotic stress conditions

“…This might suggest a role for PPC3 in the synthesis of proline and thus in the response of the plant to salt stress. Transgenic Arabidopsis plants overexpressing C 4 PEPC from Zea mays were more tolerant to salt stress due to an increased ability to synthesize amino acids, including proline (Kandoi et al 2016). On the other hand, we previously found that raised PEPC activity in Fe-deficient and/or salt-stressed barley leaves was not directly responsible for supplying C for proline synthesis (AriasBaldrich et al 2015).…”