Expression analysis of the cDNA for magnesium chelatase H subunit (CHLH) during sweet cherry fruit ripening and under stress conditions

To understand details about the molecular mechanisms of abscisic acid (ABA) action in fruit maturation, one partial cDNA (PaCHLH1) encoding magnesium chelatase H subunit (CHLH) which was proven to be an ABA receptor in Arabidopsis was cloned from sweet cherry fruit. The sequence of PacCHLH1 was 442 bp. The amino acid sequence of PacCHLH1 shows high homology to other CHLHs. PacCHLH1 expression dramatically declined after 25 days after full bloom (DAFB) which is the beginning of the ripening process, in contrast to the changes in ABA levels during this period. The application of ABA promoted endogenous ABA biosynthesis and fruit ripening but significantly decreased the expression of PacCHLH1 in fruits. No significant correlation was observed between the PacCHLH1 transcript and ABA accumulation in dehydrated fruits. In dehydrated leaves, the ABA and PacCHLH1 transcript levels were both up-regulated.