Promoting Plant Health: Potential for the Use of Plant-associated Micro-organisms in the Biological Control of Pathogens and Pests in Sugarcane

Bacteria and fungi that colonise plant surfaces and internal plant tissues (epiphytes and endophytes respectively) are ubiquitous, residing latently or actively colonising the plant locally as well as systemically. Endophytic microorganisms generally originate from the epiphytic communities of the root or aerial surfaces as well as from within seed material. Besides entering plants through natural openings or wounds, many endophytes appear capable of actively penetrating their hosts using hydrolytic cellulases and pectinases. In these respects endophytes resemble pathogens. Historically many of these microorganisms have been thought to be weakly virulent plant pathogens. However, some have since been discovered to have beneficial effects on host plants, such as growth promotion and increased resistance against plant pathogens, insect pests and nematodes. Increased resistance can occur through competitive exclusion, direct antibiosis and induced systemic resistance in the plant, or combinations of these. Conversely, some epiphytes and endophytes might be regarded as plant antagonists in that they retard plant growth and increase susceptibility to pathogens, pests and nematodes. This review assesses the potential for the biological control of important sugarcane pathogens and pests using beneficial epiphytic and endophytic microorganisms based on results achieved with other crop plants.