Phosphoenolpyruvate carboxykinase (PEPCK) deficiency affects the germination, growth and fruit sugar content in tomato ( Solanum lycopersicum L.)

Overexpression of the phosphoenolpyruvate carboxykinase gene (<i>SlPEPCK</i>) promotes soluble sugar accumulation in fruit and post-germination growth of tomato (<i>Solanum lycopersicum</i> L.)

“…Our recent study reported that SlPEPCK is only functional PEPCK gene in tomato plant (Huang et al 2015). In accordance with the result, PEPCK activity was increased by the overexpression of SlPEPCK gene (Figures 1 and 4).…”

“…However, the physiological role of PEPCK in plant and fruit development remained to be elucidated in tomato. Recent studies on RNAi transgenic tomato plants revealed that PEPCK suppression leads to reduced sugar contents accompanied by an increase in malate in ripening fruit (Huang et al 2015;Osorio et al 2013). These results indicate the involvement of PEPCK and gluconeogenesis in sugar accumulation and dissimilation of organic acid metabolism during fruit ripening.…”

“…The specific amplification of a single transcript was confirmed by single dissociation peaks and calculated based on calibration curves. A PEPCK enzyme assay was performed following a procedure described by Huang et al (2015). Tomato seed or fruit tissue (200 mg) was homogenized in a chilled mortar Copyright © 2015 The Japanese Society for Plant Cell and Molecular Biology containing 1 ml of ice-cold 200 mM Bicine-KOH (pH 9.8) and 50 mM dithiothreitol (DTT).…”

“…Soluble sugars, malate and citrate contents were measured following a procedure described by Huang et al (2015). For sugar and organic acid measurements, 500 mg of frozen fruit powder was suspended in 500 µl of MilliQ water and incubated at 99°C for 5 min to inactivate the sugar degradative enzymes and then centrifuged at 13,200 rpm for 10 min at 4°C.…”

“…Recent studies on tomato lines in which endogenous SlPEPCK was suppressed by RNA interference (RNAi) proved the involvement of PEPCK in soluble sugar accumulation and dissimilation of organic acids during fruit ripening (Huang et al 2015;Osorio et al 2013). Furthermore, systemic suppression of SlPEPCK by the constitutive 35S promoter resulted in suppression of post-germination growth of transgenic tomato seedlings (Huang et al 2015), suggesting that PEPCK and gluconeogenesis also participate in carbohydrate supply during tomato germination through a similar mechanism to that which occurs in fat-storing seed plants. On the other hand, information about the effect(s) of excessive PEPCK on fruit metabolism and post-germination growth of plants is limited.…”