Proline, a multifaceted signalling molecule in plant responses to abiotic stress: understanding the physiological mechanisms

Abstract

Abiotic stresses have a detrimental impact on plant growth and productivity and are a major threat to sustainable crop production in rapidly changing environments. Proline, an important amino acid, plays an important role in maintaining the metabolism and growth of plants under abiotic stress conditions. Many insights indicate a positive relationship between proline accumulation and tolerance of plants to various abiotic stresses. Because of its metal chelator properties, it acts as a molecular chaperone, an antioxidative defence molecule that scavenges reactive oxygen species (ROS), as well as having signalling behaviour to activate specific gene functions that are crucial for plant recovery from stresses. It also acts as an osmoprotectant, a potential source to acquire nitrogen as well as carbon, and plays a significant role in the flowering and development of plants. Overproduction of proline in plant cells contributes to maintaining cellular homeostasis, water uptake, osmotic adjustment and redox balance to restore the cell structures and mitigate oxidative damage. Many reports reveal that transgenic plants, particularly those overexpressing genes tailored for proline accumulation, exhibit better adaptation to abiotic stresses. Therefore, this review aims to provide a comprehensive update on proline biosynthesis and accumulation in plants and its putative regulatory roles in mediating plant defence against abiotic stresses. Additionally, the current and future directions in research concerning manipulation of proline to induce gene functions that appear promising in genetics and genomics approaches to improve plant adaptive responses under changing climate conditions are also highlighted.

Nitrogen application alleviates salt stress by enhancing osmotic balance, ROS scavenging, and photosynthesis of rapeseed seedlings (Brassica napus)

“…It may be due to that Pro could maintain osmotic balance, scavenge free radicals and singlet oxygen, stimulate antioxidant enzyme activity, and maintain the stability of proteins. 49 SP had a positive correlation with antioxidant enzymes, GSH, and ASA ( P < .01). It may be due to that SP has similar components to antioxidant enzymes and GSH, and ASA could promote the synthesis of SP.…”

Changing Temperature Conditions during Somatic Embryo Maturation Result in Pinus pinaster Plants with Altered Response to Heat Stress

“…Heat tolerance is acquired when, in response to the excessive production of ROS, plants initiate heat stress responsive pathways for ROS-scavenging, such as the accumulation of proline and other osmolytes. ABA, the hormone regulating stomatal aperture under heat stress, has been suggested to be responsible for the initiation of other physiological responses, such as the accumulation of proline in stressed plants [24,27]. Proline has diverse roles, such as stabilizing proteins, membranes, and subcellular structures, protecting cellular functions by scavenging ROS, and acting as a signaling molecule [23].…”

“…Furthermore, proline has additional roles, such as stabilizing proteins, membranes, and subcellular structures, protecting cellular functions by scavenging ROS, and acting as a signalling molecule [23]. Thus, proline plays an important role in maintaining the metabolism and growth of plants under abiotic stress conditions and many reports indicate a positive relationship between proline accumulation and tolerance of plants to various abiotic stresses [24].…”

Abiotic Stresses Elicitation Potentiates the Productiveness of Cardoon Calli as Bio-Factories for Specialized Metabolites Production

“…Both salinity and low temperature induce osmotic alteration in plant cells, but salinity additionally creates ionic imbalance (i.e., excess sodium and associated potassium deficiency) [ 52 ], which could have exerted a stronger inhibition on the growth of cardoon calli than chilling. Opposite to NaCl-treated calli, the growth of chilled calli recovered after 14 days, possibly reflecting an osmotic adjustment through accumulation of osmolytes that usually keep cells turgid for growth [ 53 ]. In line with this observation, the value of lipid peroxidation revealed that chilling stress is successfully counterbalanced by the plant’s antioxidant machinery as suggested by the level of MDA that was even lower than the control.…”