Abstract
The ATPase associated with various cellular activities (AAA) protein of tobacco is specifically induced during the early phase of the HR, with a role in regulation of the defense system against pathogen. Suppression of NtAAA1 plants exhibited enhanced resistance to pathogen in comparison with WT plants. In order to clarify the molecular mechanism, we performed yeast two hybrid screening and identified a gene encoding an ADP ribosylation factor (ARF), a small GTP binding protein. In animal cells, ARF is known to be directly involved in regulation of vesicular trafficking and activation of phosholipase D. To date, plant ARF was shown to enhance disease resistance to pathogens, to induce salicylic acid (SA) -activated PR genes, and to interact with phospholipase D to increase jasmonic acid (JA) formation. NtAAA1 and NtARF are conceivable to be involved in regulation of PR gene expression by NtAAA1 functioning as a negative regulator for ARF.
