Expression profile of gene encoding Kelch repeat containing F-box protein (PmF-box1) in relation to the production of green leaf volatiles

Abstract

Persicaria minor is one of the native aromatic plants in Malaysia and widely used in traditional foods and medicines. Previous studies have shown that treatment of P. minor with jasmonic acid upregulated genes involved in the secondary metabolites production and also gene encoding an F-box protein named PmFbox-1. It is known that F-box proteins play important roles in gene expression regulatory. However, the function of PmF-box1 protein is still unknown. In this study, the full length cDNA sequence of PmF-box1, with NCBI accession number JQ429325, consisting of 2768 bp was isolated followed by characterization of the deduced protein sequence of 487 amino acids. The putative F-box protein belongs to Kelch repeat-containing F-box protein family (KFB) and has a moderate level of homology with other F-box proteins from different organisms, showing a maximum identity score of 60 % with an F-box motif and two conserved kelch repeat motifs. Time course semi-quantitative reverse-transcriptase PCR gel image analyses showed that PmF-box1 was induced after JA treatment, indicating that PmF-box1 is a JA inducible gene. PmF-box1 also differentially expressed in different tissues after treatment with JA, indicating a spatial regulation of its activity. Interestingly, there was high correlation in the expression pattern between PmF-box1 and PmADH1 (P. minor Alcohol dehydrogenase 1) (R = 0.90 ± 0.05) after treatment with 150 μM JA, indicating that PmF-box1 possibly involves in regulating the activity of PmADH1. The content of hexanal was significantly increased in JA-treated plants and even higher in JA plus SA-treated plants. The level of six carbon alcohols was increased at 48 hours after JA treatment, consistent with the upregulation of PmADH1 in JA treated plants. These results suggest that PmF-box1 encodes a KFB-type F-box protein that may be involved in plant stress signaling by influencing the expression of PmADH1; thus, modulating the production of green leaf volatiles.