Is proline accumulation per se correlated with stress tolerance or is proline homeostasis a more critical issue?

Abstract

Proline has been recognized as a multi-functional molecule, accumulating in high concentrations in response to a variety of abiotic stresses. It is able to protect cells from damage by acting as both an osmotic agent and a radical scavenger. Proline accumulated during a stress episode is degraded to provide a supply of energy to drive growth once the stress is relieved. Proline homeostasis is important for actively dividing cells as it helps to maintain sustainable growth under long-term stress. It also underpins the importance of the expansion of the proline sink during the transition from vegetative to reproductive growth and the initiation of seed development. Its role in the reproductive tissue is to stabilize seed set and productivity. Thus, to cope with abiotic stress, it is important to develop strategies to increase the proline sink in the reproductive tissue. We give a holistic account of proline homeostasis, taking into account the regulation of proline synthesis, its catabolism, and intra-and intercellular transport, all of which are vital components of growth and development in plants challenged by stress.

A novelAzotobacter vinellandii(SRIAz3) functions in salinity stress tolerance in rice

“…13 The parallel evidence involving increased proline and plant tolerance to stress suggests that proline could have a protective function. 12 In this study, the elevated level of proline in A. vinellandii inoculated rice (Fig. B) provide plant tolerance to sustain its growth under 200 mM NaCl.…”

“…Proline homeostasis is essential for meristematic cells owing to its function to retain sustainability of plant growth under prolong stress. 12 In rice, the higher proline accumulation in response to salinity stress confers plant tolerance to high salinity. 13 The parallel evidence involving increased proline and plant tolerance to stress suggests that proline could have a protective function.…”

The Effects of Night-time Temperatures on Physiological and Biochemical Traits in Rice

“…Finally, no differences in proline content among genotypes and/or temperatures were found ( Table 2). The lack of differences on leaf proline levels under HNT can be associated with low oxidative damage in almost all genotypes, since this amino acid has been recognized as a multi-functional molecule under abiotic stresses, showing a role as an antioxidant (Kishor and Sreenivasulu, 2014).…”

Producing Transgenic Thompson Seedless Grape (Vitis vinifera) Plants using Agrobacterium tumefaciens

“…A plant protecting him against the lethal effects of salinity by over accumulation of proline that may be resulting from salinity inducible uptake of exogenous proline confers (Fichman et al, 2014). Several studies have highlighted the possible mechanisms of proline accumulation under stress condition; 1-by restricting entrance of non-metabolisable ions such as sodium, transporting them to vacuoles and or excluding them from the cytosol and thus reducing their toxicity (Verbruggen and Hermans, 2008); 2-acting as a non-enzymatic osmoprotectant which suggests it could replace water at protein surfaces, in protein complexes or in membranes Hasegawa et al (2000); 3-acting as both an osmotic agent and a radical scavenger (Kishor and Sreenivasulu, 2014) and; 4-act to balance cell redox status and to buffer cytosolic pH (Maggio et al, 2002).…”