Role of polyamines in heavy metal stressed plants

Polyamines (PAs) have a fundamental role in the functioning of plant cells when exposed to heavy metal (HM) stress conditions. PAs play a significant importance in growth, physiology, reproduction and production in plants. In recent years, PAs have been widely reported for their role in abiotic stresses tolerance like in salt, drought, and heavy metals toxicity. PAs are regarded as growth constituents because of their great importance in plants towards development and stress tolerance. PAs have an essential role in plant cell signaling and defense; by showing changes in endogenous levels through exogenous exposure will improve plant growth, development, and stress tolerance. Soil contamination with HMs from natural and man-made activities is a universal problem in recent times of industrialization, which in turn affects the atmosphere, human health and yield production. Therefore, it is essential to develop effective mechanisms that can help in the protection of crop yield and food quality, given the rate of increasing pollution. Finding ways to increase tolerance is a significant task of plant biologists. So it is very important to focus on the PAs in mitigating abiotic stress to maintain normal growth and product yield. This review summarises the identified response of PAs in HMs-stressed plants conferred on a "case-study" basis, of metals like Al, As, Cd, Cr, Cu, Fe, Pb, Mn, Hg, Ni and Zn.