Characterization of a newly identified rice chitinase-like protein (OsCLP) homologous to xylanase inhibitor

Abstract

BackgroundDuring rice blast fungal attack, plant xylanase inhibitor proteins (XIPs) that inhibit fungal xylanase activity are believed to act as a defensive barrier against fungal pathogens. To understand the role of XIPs in rice, a xylanase inhibitor was cloned from rice. The expression of this gene was examined at the transcriptional/translational levels during compatible and incompatible interactions, and the biochemical activity of this protein was also examined.ResultsSequence alignment revealed that the deduced amino acid sequence of OsCLP shares a high degree of similarity with that of other plant TAXI-type XIPs. However, recombinant OsCLP did not display inhibitory activity against endo-1,4-β-xylanase enzymes from Aureobasidium pullulans (A. pullulans) or Trichoderma viride (T. viride). Instead, an in-gel activity assay revealed strong chitinase activity. The transcription and translation of OsCLP were highly induced when rice was exposed to pathogens in an incompatible interaction. In addition, exogenous treatment with OsCLP affected the growth of the basidiomycete fungus Rhizoctonia solani through degradation of the hyphal cell wall. These data suggest that OsCLP, which has chitinase activity, may play an important role in plant defenses against pathogens.ConclusionsTaken together, our results demonstrate that OsCLP may have antifungal activity. This protein may directly inhibit pathogen growth by degrading fungal cell wall components through chitinase activity.

Susceptibility of Wheat Varieties to Soil-Borne <i>Rhizoctonia</i> Infection

“…Discoveries show that both anatomic and physiological features are involved into manifestation. Thus, the structure and composition of cell wall might have importance; the resistance to fungal xylanase is a tolerance factor [50]. The multivariate analysis of our experimental results supports the multigenic character of wheat response, although no dominant factor was revealed.…”

A secreted chitinase‐like protein (OsCLP) supports root growth through calcium signaling in Oryza sativa

“…Here, OsCLP was also identified as a secretory protein with a high level of expression in the roots (Figs and ). Previously, a strong chitinase activity was observed in the recombinant OsCLP, suggesting its possible involvement in the defense mechanisms (Wu et al ).…”

“…As of today, only one rice chitinase‐like protein OsCTL1 has been characterized that functions in rice plant development (Wu et al ) with no obvious classical chitinase activity associated with it. However, a strong chitinase activity of OsCLP was detected in vitro (Wu et al ), illuminating that OsCLP regulates rice development by a different mechanism.…”

“…Proteins separated on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) were blotted on a PVDF membrane using a semi‐dry electrophoresis system (Hoefer, Holliston, MA). The blotted membrane was blocked in TTBS (50 m M tris‐HCl pH 8.2, 0.1% Tween 20, 150 m M NaCl) containing 7% skim milk overnight at 4°C and then incubated with 1:1000 anti‐OsCLP antibody generated previously (Wu et al ). Anti‐rabbit IgG secondary antibody 1:5000 was used for the antigen–antibody interaction.…”

“…Previously, we characterized a Magnaporthe oryzae ‐induced chitinase‐like protein (OsCLP) from rice. Recombinant OsCLP protein exhibited strong antifungal activity (Wu et al ). Here, we extend our previous study on characterization of OsCLP and show its involvement in rice growth regulation, which seems to be mediated by reducing the calcium concentration inside the cells.…”