Fungal Entomogenesis Of Chitin

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Nutrients deficiency and higher competition for nutrients in the soil is a major problem in most ecosystems. In order to overcome this deficiency of nutrients, plants have developed symbiotic association with beneficial microbes and endophytes (Clark and Zeto 2000). Endophytic fungi have been reported to transfer soil limiting nutrients such as nitrogen and phosphorus (Govindarajulu et al. 2005; Guether et al. 2009; Behie and Bidochka 2014) to their host plant whereas fungi received plant-derived carbohydrates (Bonfante and Genre 2010). Metarhizium and Beauveria having dual life cycle suggested that insect pathogenesis translocated insect-derived nitrogen to plants (Behie and Bidochka 2014). In this way, plants colonized with fungal entomopathogens …show more content…
Chitinases catalyze the hydrolytic cleavage of β-1,4-glycoside bond of chitin (Kasprzewska 2003; Jitonnom et al. 2011) and also hydrolyze the deacetylated form of chitin, which is referred to as chitosan. Chitinases digest the chitosan polysaccharide chain at the remaining acetylated sugar residues. Chitin and chitosan are abundant in fungal and some algal cell walls, in bacteria and in the exoskeleton of invertebrates (Li and Roseman 2004). Lipochitooligosaccharides or Nod factors produced by rhizobia essentially consist of a chitin backbone of 3–5-N-acetylglucosamine residues with N-acyl group attached to the non-reducing sugar and a variety of additional substituents attached to the glucosamine residues (den Hartog et al. 2003). Bacterial peptidoglycan, a polymer of β-1,4-linked N-acetylglucosamine and N-acetylmuramic acid residues, is cleaved by plant chitinases that have additional lysozyme or lysozyme-like activity (Kasprzewska 2003). Plant cell wall glycoproteins containing N-acetylglucosamine, are considered to be the endogenous substrate for plant chitinases (Dyachok et al. 2002). In fungi, insects and crustaceans that contain chitin as a cell wall component, the major role of chitinases appears to be in modification of chitin. Chitinases are also considered to have a role in defense or in enhancing competitiveness in higher plants and animals that do not contain chitin. Bacterial chitinases are mainly involved in degrading chitin to provide carbon and nitrogen nutrition to the cells (Patil et al. 2000). In plants, chitinases have been implicated both in biotic and abiotic stress responses as well as in growth and development (Sharma et al. 2011). Chitinases represent a subgroup of pathogenesis-related (PR) proteins that were initially discovered as proteins that are induced in host cells in response to pathogenesis (Van Loon 1985). Subsequently, it became

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