LEA Proteins in Salt Stress Tolerance

In late embryogenesis, the water content of living cell is reduced tremendously that leads to a state of dehydration and thus, might impose severe irreparable damage to cellular and macromolecular structures. However, the mature orthodox seeds can withstand severe desiccation due to role of osmoprotectants viz., reducing sugars, prolines, glycinebetaines or Late Embryogenesis Abundant (LEA) proteins. These operate on the virtue of intrinsic molecular mechanisms that alleviate multiple abiotic stresses in plants such as protein desiccation, membrane degradation, salt stress and cold and chilling stress. The LEA proteins are a group of versatile, adaptive, hydrophilic proteins considerably defined as ‘molecular shields’ for their anti-stress properties attributable to partial or complete structural randomness. On the basis of their amino acid composition and sequencing, LEA proteins have been clubbed into seven groups that are further sub divided into a number of protein sub families. Out of these, Group 2 LEA proteins called the ‘Dehydrins’ are of prime importance in the plant kingdom. The latent and unique stress remediating characteristics of this class of proteins has been further enhanced by transgenic studies, wherein the target LEA genes have been identified, sequenced to understand their molecular role in plants. Further investigations into the behavior of LEA proteins and mode of their regulation in stressed plants will facilitate in elucidating the function of LEA proteins. The present chapter reviews the versatility and role of LEA proteins in plant stress protection.