Cloning and expression of lipoxygenase genes and enzyme activity in ripening persimmon fruit in response to GA and ABA treatments

• Two persimmon fruit expressed 9-LOX genes DkLox1 and DkLox3 were cloned.
• LOX gene expression and enzymatic activity corresponded with the fruit softening process.
• ABA and GA3 treatments regulated LOX gene expression and fruit softening.
• DkLox3 is more dynamically regulated and more responsive to ABA or GA treatment.

Two genes of the lipoxygenase (LOX) family, DkLox1 and DkLox3 (GenBank accession No. JF436951 and JF436950), were cloned from persimmon fruit (Diospyros kaki L. ‘Fuping Jianshi’). Sequence analysis indicated that they belong to the 9-LOX sub-group. Transcriptional profiles of both LOX genes during fruit ripening and in response to gibberellin (GA3) and abscisic acid (ABA) treatments during postharvest storage were studied using quantitative reverse transcription PCR (qRT-PCR). The expression of DkLox1 and DkLox3 peaked at 15 d after the fruit were harvested under room temperature, corresponding to the patterns of LOX activity and ethylene production. ABA treatment accelerated the persimmon fruit softening and increased LOX enzyme activity, ethylene production and MDA content; and the expression of DkLox1 and DkLox3 peaked three days earlier than the non-treated control. By contrast, the GA3 treatment decelerated the ripening process and down-regulated the expression of DkLox1 and DkLox3 genes. The roles of LOX gene expression during persimmon fruit ripening are discussed.