Metabolic and molecular-genetic regulation of proline signaling and its cross-talk with major effectors mediates abiotic stress tolerance in plants

Abstract

Proline (Pro) accumulation is a common response of several plant species to combat abiotic stresses. Under stress conditions, Pro acts as an excellent compatible solute in the plant system, participating in the alleviation of stress sensitivity. Though the metabolic pathways associated with Pro are well studied, parts of its regulatory cascades are still not properly known. It has also been conjectured that epigenetic modifications regulate Pro metabolism during abiotic stress. Apart from Pro, the plant abiotic stress responses are essentially mediated by multiple effectors. Hence, proper analysis of the cross-talks of Pro with the other components of the abiotic stress response has turned out to be mandatory in order to design multistress-tolerant transgenic lines. Highlighting the relation between Pro and seed germination is also essential to understand the notion behind plant susceptibility and survival during stress. Generally, Pro has a universal mechanism to generate abiotic stress tolerance through stabilization of structural components, enzyme structures, and regulation of osmotic adjustments. The success achieved through recent transgenic approaches leading to more accumulation of Pro in the sink has also been focused on in the present review.