Endophyte-Mediated Biocontrol of Herbaceous and Non-herbaceous Plants
All plants in natural ecosystems appear to be symbiotic with endophytes. This includes many economically important agricultural products as well as essential food crops. The endophytes confer fitness benefits to their hosts in various and variable aspects
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Orna Liarzi and David Ezra
Abstract
All plants in natural ecosystems appear to be symbiotic with endophytes. This includes many economically important agricultural products as well as essential food crops. The endophytes confer fitness benefits to their hosts in various and variable aspects such as growth enhancement and increased reproductive success and confer tolerance to biotic and abiotic stresses. In this chapter we will focus on the biocontrol activity of endophytes, i.e., the biological effects of endophytes on herbaceous or non-herbaceous host plants and the mechanisms, if known, by which the endophytes increase the fitness of their hosts.
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Introduction
All plants in natural ecosystems appear to be symbiotic with fungal endophytes (Rodriguez and Redman 2008; Rodriguez et al. 2009b; Singh et al. 2011a). It is estimated that 20–30 % of grass species worldwide, including many economically important forage and turf grasses, are associated with endophytic fungi (Leuchtmann 1992). Throughout its motionless life, the plant is exposed to various biotic and abiotic stresses, from which it can either escape or mitigate (Rodriguez and Redman 2008). However, since grasses lack the biosynthetic capacity for the production of secondary metabolites, which O. Liarzi • D. Ezra (*) Department of Plant Pathology, ARO the Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel e-mail: [email protected]
are useful in the long-term survival strategy (Kuldau and Bacon 2008), their dependence on microorganisms that produce secondary metabolites is more pronounced. Symbiosis is defined as “the permanent association between two or more specifically distinct organisms, at least during a part of the life cycle” (de Bary 1879). The association of fungal symbionts with plants can be in a form of endophyte or as mycorrhizal fungi (Singh et al. 2011a). Unlike mycorrhizal fungi that colonize plant roots and grow into the rhizosphere, endophytes reside entirely within plant tissues and may grow within roots, stems, and/or leaves, emerging to sporulate at plant or host-tissue senescence, and their presence in the plant tissue causes no symptoms of disease (Sherwood and Carroll 1974; Hallmann et al. 1997; Carroll 1988; Stone et al. 2004). Similarly, a variety of bacteria have been reported to maintain endophytic lifestyle
V.C. Verma and A.C. Gange (eds.), Advances in Endophytic Research, DOI 10.1007/978-81-322-1575-2_18, © Springer India 2014
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O. Liarzi and D. Ezra
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in plants (Reinhold-Hurek and Hurek 2011; Mei and Flinn 2010; Dudeja et al. 2012; Rosenblueth and Martinez-Romero 2006). It is generally assumed that many bacterial endophyte communities are the product of a colonizing process initiated in the root zone (McInroy and Kloepper 1995; Sturz et al. 2000; Welbaum et al. 2004). However, they may also originate from other sources such as the phyllosphere, the anthosphere, or the spermosphere (Hallmann et al. 1997). In contrast to extensively studied grass endophytes, endophytes associated with woody angiosperms
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