Major Antifungal Activity from the Bulbs of Indian Squill Urginea indica Is a Chitinase

Abstract

We have identified a chitinase with antifungal activity in the bulbs of the plant Urginea indica(Indian squill) and purified it about 26-fold. The purified preparation contained a Mr 29 kDa protein that was an active growth inhibitor of the fungal pathogens Fusarium oxysporum and Rhizoctonia solani in an in vitro assay. Amino acid sequence analysis of the Mr 29 kDa protein revealed it to be highly homologous to the family 19 glycoside hydrolases, which are known to possess chitinase activity. The U. indica chitinase lacked a cysteine-rich N-terminal domain (characteristic of class I chitinases) and contained a conserved motif indicative of the signature 1 of family 19 glycoside hydrolases. It shared a approximately 70% sequence identity with the 26 kDa endochitinase of Hordeum vulgare, a typical class II chitinase of family 19. The five cysteines in the partial sequence of the Mr 29 kDa chitinase were found to be identical in location to five of the seven cysteines present in the catalytic domain of the H. vulgare enzyme. The molecular weight, the lack of an N-terminal cysteine-rich sequence, and the striking identity to the H. vulgare endochitinase suggest that the Mr 29 kDa U. indica protein is a putative class II chitinase. The antifungal activity is presumably mediated through the chitinolytic activity of the Mr 29 kDa protein.

First report of an antifungal amidase from Peltophorum ptercoarpum

“…It deserves mention that peltopterin is monomeric and yet has a molecular mass of 60 kDa. The majority of antifungal proteins such as thaumatin-like proteins (Chua et al, 2007) and chitinases (Shenoy et al, 2006), have a molecular mass of approximately 30 kDa. Like defensins, which are pH-stable and thermostable (Leung et al, 2008), the antifungal activity of peltopterin can withstand changes in pH and temperature.…”

“…They have been reported from a multitude of plants , animals (Clément et al, 2008), bacteria (Yadav et al, 2007) and fungi (Wang and Ng, 2006). Plant tissues that produce antifungal proteins and peptides comprise bulbs (Shenoy et al, 2006), rhizomes (Lam and Ng, 2001b), tubers (Flores et al, 2002), fruits (Ho and Ng, 2007), seeds and roots (Wang and Ng, 2000). Plant antifungal proteins are divided, based on their structure or activity, into various types.…”

Novel flavonoid glycosides from the bulbs of Urginea indica Kunth

“…The extract of the bulbs possesses hypoglycaemic and anticancer properties (Ghani, 2003). Earlier studies of the plant have resulted in the isolation of some glycoproteins, glycosides and bufadienolides, which are used as cardio-tonic agents, and possess insecticidal and antimicrobial properties (Deepak & Salimath, 2006;Deepak, Thippeswamy, Shivakameshwari, & Salimath, 2003;Patil & Torne, 1981;Shenoy, Kameshwari, Swaminathan, & Gupta, 2006). As a continuation of our phytochemical studies on medicinal plants, this article reports the isolation and structural elucidation of three novel flavonoid glycosides from the bulbs of U. indica.…”

Overexpression of the Synthetic Chimeric Native-T-phylloplanin-GFP Genes Optimized for Monocot and Dicot Plants Renders Enhanced Resistance to Blue Mold Disease in Tobacco (N. tabacumL.)

“…Examples are chitinases and chitinase-like proteins with antifungal activity towards Fusarium oxysporum and Rhizoctonia solani [8, 9], cyclophilin-like proteins with antifungal activities [10, 11], defensins and defensin-like peptides that inhibit growth of F . oxysporum and M .…”