Abstract

In plants, phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) catalyzes the conversion of L-phenylalanine to trans cinnamic acid in the first step of phenylpropanoid pathway. We previously isolated cDNA clones encoding PAL from asparagus spears and observed that the level of transcripts correlated well with increase enzyme activity and lignification. In order to identify factors regulating the postharvest deterioration of another important Asian vegetable bamboo (Phyllostachys edulis) shoot, we have now isolated PAL (pBA-PAL), cDNA clone from a cDNA library prepared from harvested bamboo shoot using reverse transcriptase-polymerase chain reaction. The partial cDNA clone encodes an mRNA of 527 bp and the derived amino acid sequence is highly homologous to PAL from rice, barely, maize and asparagus. Northern blot analysis showed increasing trend in the level of pBA-PAL mRNA reaching a peak after 3 d of storage at 20°C, which coincided well with enzyme activity. Our results demonstrate that during the postharvest storage of bamboo shoot PAL activity is regulated by increase level of pBA-PAL mRNA suggesting that the increase might be a response to the wounding associated with harvest.