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ABSTRACT
Twenty three strains of selected entomopathogenic fungi were tested for the production of chitinolytic enzymes and their involvement in the suppression of Colletotrichum falcatum, red rot pathogen of sugarcane. Among twenty three strains tested for chitinolytic activity, 9 strains showed a clearing zone on chitin-amended agar medium. Among these, entomopathogenic fungal strains ARSEF-6646, ARSEF-6647, ARSEF-6648, ARSEF-6650 and ARSEF-2417Beauveria bassiana strains produced clearing zones of a size larger than 10 mm. The antifungal activity of these strains increased when chitin was incorporated into the medium. When mycelial discs of the pathogen were treated with the secondary fungal mycelia, the results indicated that antagonistic B. bassiana caused a higher level of lysis of the pathogen mycelium, and the inhibitory effect was more pronounced when the lytic enzymes were produced using chitin as carbon source.
MS History: 19.09.2013 (Received)-16.03.2014 (Revised)-25.03.2014 (Accepted)
Key words: Entomopathogenic fungi, Colletotrichum falcatum, red rot disease, sugarcane.
INTRODUCTION
Sugarcane is an important crop in India because of its high commercial value. Colletotrichum falcatum, phytopathogenic fungus causes the red rot disease triggering severe loss of yield in many parts of sugar cane growing states in India (Alexander and Viswnathan, 1996). Fungicides have commonly been used for the management of this disease; however, resistance of pathogens to conventional fungicides is becoming a major problem and in turn fungicides affect environment and human health. Recently, the use of biological control has increased. Production of chitinase from microorganisms has been suggested for the control of red rot disease (Viswanathan and Samiyappan, 2001). Entomopathogenic fungi were well known to control agricultural pests. Suppression of several plant pathogens using entomopathogenic fungi was well documented. In vitro bioassay studies reported that mycelial growth inhibition of various plant disease causing fungi such as Gaeumannomyles graminis (Renwick et al., 1991), Fusarium oxysporum, Armillaria mellea, Rosellinia necatrix (Reisenzein and Tiefenbrunner, 1997), Fusarium oxysporum, Botrytis cinerea (Bark et al., 1996), Pythium ultimum, Rhizoctonia solani (Vesely and Kobava, 1994; Lee et al., 1999), Pythium sp.(Clark et al., 2006; Ownley et al., 2008) and Rhizoctonia Table 1. Source of Entomopathogenic fungi collection. (Ownley et al., 2000; Ownley et al., 2004) using entomopathogenic fungus Beauveria bassiana. Another entomopathogenic fungus Lecanicillium sp is also known to show inhibition of plant pathogens such as Powdery mildew (Verhaar...