Role of Proline and Glycine Betaine in Overcoming Abiotic Stresses

Environmental and abiotic stresses such as drought, waterlogging, chilling, salinity, high temperatures, pollutions resulting from the use of pesticides and fertilizers, etc., have gained more importance in the last three decades due to changes in environmental conditions. Their combinations and their interactions with biotic stresses have resulted in more drastic consequences on crop plants including sudden death, permanent DNA damages, reduced resistance or tolerance levels to further stress, inhibition of DNA repair, etc. To overcome such stress factors, the use of biostimulants or osmoprotectants has been one of the most practical approaches so far. Not only the use of osmoprotectants such as proline, glycine betaine, or amino acids would help the stressed plants, but also their transgenic expressions would be beneficial. However, such osmoprotectants might have cross talk with other biomolecules in the cell system of crop plants during stress and their positive roles might be nullified. In this chapter, the role of osmoprotectants has been evaluated under abiotic stress conditions as well as their significance and expressions under biotic stress conditions.