Osmolytes: Proline metabolism in plants as sensors of abiotic stress

Proline accumulation occurs in a large range of plant species in retaliation to the numerous abiotic stresses. An exclusive research pattern suggests there is a pragmatic relation between proline accumulation and plant stress tolerance. In this review, we will discuss the metabolism of proline accumulation and its role in stress tolerance in plants. Pertaining to the literature cited clearly indicates that not only does it acts as an osmolyte, it also plays important roles during stress as a metal chelator and an antioxidative defence molecule. Moreover, when applied exogenously at low concentrations, proline enhanced stress tolerance in plants. However, some reports point out adverse effects of proline when applied at higher doses. Role of proline gene in seed germination, flowering and other developmental programmes; thus creation of transgene overexpressing this gene would provide better and robust plants. In this context this review gives a detailed account of different proline gene over-expressed in all the trans-genic crops so far.