Proline Mechanisms of Stress Survival

Abstract

Significance: The imino acid proline is utilized by different organisms to offset cellular imbalances caused by environmental stress. The wide use in nature of proline as a stress adaptor molecule indicates that proline has a fundamental biological role in stress response. Understanding the mechanisms by which proline enhances abiotic/biotic stress response will facilitate agricultural crop research and improve human health. Recent Advances: It is now recognized that proline metabolism propels cellular signaling processes that promote cellular apoptosis or survival. Studies have shown that proline metabolism influences signaling pathways by increasing reactive oxygen species (ROS) formation in the mitochondria via the electron transport chain. Enhanced ROS production due to proline metabolism has been implicated in the hypersensitive response in plants, lifespan extension in worms, and apoptosis, tumor suppression, and cell survival in animals. Critical Issues: The ability of proline to influence disparate cellular outcomes may be governed by ROS levels generated in the mitochondria. Defining the threshold at which proline metabolic enzyme expression switches from inducing survival pathways to cellular apoptosis would provide molecular insights into cellular redox regulation by proline. Are ROS the only mediators of proline metabolic signaling or are other factors involved? Future Directions: New evidence suggests that proline biosynthesis enzymes interact with redox proteins such as thioredoxin. An important future pursuit will be to identify other interacting partners of proline metabolic enzymes to uncover novel regulatory and signaling networks of cellular stress response. Antioxid. Redox Signal. 19, 998-1011.

Improvement ofex vitroacclimatization of mulberry plantlets by supplement of abscisic acid to the last subculture medium

“…Proline is considered as the primary accumulated metabolite in different stress conditions, which contributes to maintain the water absorptive capacity and improve the drought tolerance for plant survival and establishment (Kishor et al 1995;Liang et al 2013;Molinari et al 2007). Proline accumulation may occur due to the physiological responses induced by osmotic stress in plants .…”

Agricultural uses of plant biostimulants

“…These include the twenty structural amino acids involved in the synthesis of proteins as well as non-protein amino acids which are found abundantly in some plant species (Vranova et al 2011). There is considerable evidence that exogenous application of a number of structural and non-protein amino acids, including glutamate, histidine, proline, and glycine betaine can provide protection from environmental stresses or are active in metabolic signalling (Sharma and Dietz 2006;Forde and Lea 2007;Vranova et al 2011;Liang et al 2013). Several non-protein amino acids have also been shown to have roles in plant defense which is outside the scope of this review (see Huang et al 2011;Vranova et al 2011).…”

Proline levels, oxidative metabolism and photosynthetic pigments during in vitro growth and acclimatization of Pitcairnia encholirioides L.B. Sm. (Bromeliaceae)

“…Proline is the primary accumulated metabolite in different stress conditions, which is essential for plant establishment and tolerance (Molinari et al, 2007;Liang et al, 2013).…”