Allantoin: Emerging Role in Plant Abiotic Stress Tolerance

Abstract

Allantoin is an intermediate product of purine catabolic pathway that helps in nitrogen mobilization in plants. It is ubiquitously present in the plant kingdom and serves as an important N form transported from source to sink. During the recent years, allantoin has emerged as a molecule involved in increasing stress tolerance in plants. Higher allantoin biosynthesis and accumulation in plants is correlated with an increase in different abiotic stress tolerance such as drought, salt, cold, heavy metals and irradiance. Increased allantoin accumulation subsequently activates ABA (abscisic acid) biosynthetic genes which in turn activate its hallmark downstream stress-related genes such as RD26 and 29 (response to desiccation), CAT2 (catalase2), Mn/Fe/Cu/Zn superoxide dismutases and SOS1 (salt overly sensitive 1). External application of allantoin on plants acts as signalling molecule that induces a complex crosstalk between ABA and JA (Jasmonic acid) pathway resulting in increased stress tolerance in plants. Recently, allantoin has been attributed to the role of kin recognition in plants, which highlights its role as a signal molecule that facilitates inter-plant interactions. In this review, we present the up to date understanding of this Nitrogen carrying compound, which has recently emerged as a molecule that plays important roles in abiotic stress tolerance in plants.