Abstract
Xylanase inhibitor is a kind of proteinaceous inhibitor which occurs only in monocots, although, its physiological function still remains unclear. We have already identified a novel XIP-type xylanase inhibitor (OsXIP) as a stress responsive-gene in rice with microarray analysis. Now, we examined the molecular property and expression profile of OsXIP to elucidate its physiological role in rice.
Purified recombinant OsXIP which was produced in Escherichia coli inhibited the activity of xylanase from Trichoderma longibrachiatum and Trichoderma viride by 50%, but not from Aspergillus niger. The expression of OsXIP was detected only in immature seed under the normal condition, and drastically induced in root by wounding, methyl jasmonate and infection with Rhizpus oryzae, a pathogenic fungus, suggesting that OsXIP may be involved in development of seed and defense mechanisms toward pathogen in root.
