Identification and expression analysis of a pathogenresponsive PR-1 gene from Chinese wild Vitis quinquangularis
In response to pathogen attacks, plant produces a wide range of pathogenesis-related (PR) proteins. PR-1 genes represent the first identified PR gene family. Most members of PR-1 gene family are not inducible by pathogen attacks. In this study, we identified a pathogen-responsive PR-1 gene designated as VqPR-1 (GenBank accession no. JN256202), in a subtractive suppression hybridization (SSH) cDNAlibrary from Elsinoe ampelina-inoculated young leaves of Chinese wild Vitis quinquangularis clone ‘shang-24’. VqPR-1 protein contained the requisite signal sequence at the N-terminus, a conserved three-dimensional structure called ‘PR-1 fold’ and a highly conserved six-cysteine motif. Expression level of VqPR-1 rose rapidly in response to E. ampelina infection. The three tested plant defence signaling molecules, salicylic acid (SA), ethephon (Eth) and methyl jasmonate (MeJA) all triggered an induction of VqPR-1. However, the induction by addition of MeJA was weaker than that induced by SA and Eth. In addition, the response to inoculation with E. ampelina or treatment with signaling molecules, was sometimes a suppression of VqPR-1 gene expression. The highest expression of VqPR- 1 was observed in flowers, stems and leaves, while low-level or no obvious transcripts were detected in pericarps and tendrils, respectively.
Key words: Vitis quinquangularis, PR-1 gene, Elsinoe ampelina, expression analysis.