Sahand Amini - Department of Agricultural Biotechnology, College of Agriculture Isfahan University of Technology, Isfahan, Iran
Cyrus Ghobadi - Department of Horticultural Sciences, College of Agriculture Isfahan University of Technology, Isfahan, Iran
Ahad Yamchi - Department of Plant Breeding and Biotechnology, College of Plant Production Gorgan University of AgricultureScience and Natural Recourses, Gorgan, Iran

Under osmotic stresses, proline accumulation is an important response of plants to these conditions.Proline is a compatible osmolyte which affects many cellular and molecular aspects of a plant in both normal andstressful situations. Proline is shown to be involved in plant development in normal conditions and in conferringresistance to a plant under biotic and abiotic stresses. Therefore, many surveys have already been conducted to unveilits mechanisms and signaling pathways, so that it might be considered as an insight into resolving growing challengesof agriculture, drought and soil salinity. Δ1-pyrroline-5-carboxylate synthetase (P5CS), one of the two main enzymes inthe proline biosynthesis pathway of the glutamate precursor, has been demonstrated to play a significant role in prolineaccumulation in plants under water stresses. Regarding the role of P5CS under the osmotic stress, there arecontroversial observations in various plants which casts doubts regarding whether P5CS is a rate-limiting enzyme in thepathway or not. Obviously, transgene P5CS is proved to give higher resistance to transgenic plants under drought andsalinity, by elevating proline content. In this review of literature, proline and its identified various functions in plants,characteristics of P5CS enzyme, signals, inducers and inhibitors of P5CS gene and the expression pattern of P5CSunder differential conditions in studied plant species are discussed. Finally, some of the important features of thetransgenic plants overexpressing P5CS have been summarized.

Abiotic Stress, Overexpressing, Proline, P5CS, Transgenic Plants