proline accumulation and osmotic stress: an overview of p5cs gene in plants

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 and stressful situations. proline is shown to be involved in plant development in normal conditions and in conferring resistance to a plant under biotic and abiotic stresses. therefore, many surveys have already been conducted to unveil its mechanisms and signaling pathways, so that it might be considered as an insight into resolving growing challenges of agriculture, drought and soil salinity. δ1-pyrroline-5-carboxylate synthetase (p5cs), one of the two main enzymes in the proline biosynthesis pathway of the glutamate precursor, has been demonstrated to play a significant role in proline accumulation in plants under water stresses. regarding the role of p5cs under the osmotic stress, there are controversial observations in various plants which casts doubts regarding whether p5cs is a rate-limiting enzyme in the pathway or not. obviously, transgene p5cs is proved to give higher resistance to transgenic plants under drought and salinity, 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 p5cs under differential conditions in studied plant species are discussed. finally, some of the important features of the transgenic plants overexpressing p5cs have been summarized.