A review on plant and pathogen derived carbohydrates, oligosaccharides and their role in plant's immunity

Abstract

Polysaccharides play a pivotal role throughout the life cycle of plants in a diversified manner which includes the building of a physical structure, storing the energy, participating in metabolic events, signaling, and in defense responses. Many pathogens have evolved to utilize plants as a nutrient source breaching the preformed barriers like tough polysaccharide-made cell wall which acts as a first line of defense in plants. However, the pathogens overcome this primary barrier by secreting hydrolytic enzymes to dissolve the cell walls. In a never-ending war between plants and pathogens, plants developed the ability to recognize the degraded products of cell walls and activate an additional defense response, referred to as an induced defense. Pathogen-associated polysaccharides such as lipopolysaccharides, bacterial-originated peptidoglycan, fungal-derived β-glucan, chitin, chitosan originated oligosaccharides are recognized by the plants and elicit defense responses. Because of the increasing evidence on the utilization of polysaccharides in plant protection, the current review is focused on various nano-polysaccharides and their potential role in sustainable agricultural practices.