A novel aspartic acid protease gene from pineapple fruit (Ananas comosus): cloning, characterization and relation to postharvest chilling stress resistance

Abstract

A full-length cDNA encoding a putative aspartic acid protease (AcAP1) was isolated for the first time from the flesh of pineapple (Ananas comosus) fruit. The deduced sequence of AcAP1 showed all the common features of a typical plant aspartic protease phytepsin precursor. Analysis of AcAP1 gene expression under postharvest chilling treatment in two pineapple varieties differing in their resistance to blackheart development revealed opposite trends. The resistant variety showed an up-regulation of AcAP1 precursor gene expression whereas the susceptible showed a down-regulation in response to postharvest chilling treatment. The same trend was observed regarding specific AP enzyme activity in both varieties. Taken together our results support the involvement of AcAP1 in postharvest chilling stress resistance in pineapple fruits.

Keywords: AP; Aspartic acid protease; Blackheart; EDTA; PCT; PSI; Pineapple; Postharvest chilling treatment; RACE; RT-qPCR; Stress resistance; aspartic acid protease; ethylenediamine-tetraacetic acid; plant specific insert; postharvest chilling treatment; rapid amplification of cDNA ends; reverse transcription-quantitative polymerase chain reaction.