The results of qRT-PCR confirmed that 1-MCP-treated fruit
showed higher expression levels of MdPEPC and MdcyMDH, along
with higher activity of PEPC and cyNAD-MDH and higher malate
content, compared with control fruit. But transcript-level of
MdcyME was not different in all treatments, expression of MdPEPCK
displayed a quite different trend with PEPCK activity during fruit
storage. Inconsistent patterns between gene transcript levels and
enzymatic activity may be due to PEPCK activity is mediated by
multiple genes controlling or post-translational regulation. Several
papers have shown that NADP-ME is regulated at the posttranslational
level by cytosolic pH and malate concentration (Yang
et al., 2011; Yao et al., 2009).