Polyamines and Their Metabolic Engineering for Plant Salinity Stress Tolerance

Abstract

Polyamines (PAs) are small polycationic aliphatic amines and are ubiquitous in the plant kingdom. They play important roles in plant growth, development, and stress responses. Several research reports have established a correlation between their accumulation and salt stress tolerance in different plant species. Creditable research in the recent past has proved their vital roles in stress responses and adaptation strategies employed by plants, including scavenging of free radicals, neutralization of acids, and stabilization of cell membranes. They are able to bind several charged molecules including DNA, proteins, membrane phospholipids, and pectic polysaccharides, and have been credited with roles in protein phosphorylation and post-transcriptional modifications. They also play important roles in plant growth regulation, as well as acting as signaling molecules. Owing to their diverse functions in plant growth, development, and stress responses, they have emerged as potent targets for metabolic engineering to confer salt stress tolerance on manipulated plants. This chapter highlights their biosynthesis and transport, their exogenous applications to alleviate salt stress, and their metabolic engineering for developing salt-tolerant plants.