Investigating physiological and biochemical

2.3.2.1.1. Proline 
In general, proline contents are higher in higher plants but its concentration 
increases markedly when induced under salt stress (Dogan et al., 2010; Nabati et al., 
2011). Proline protects proteins from denaturation, cause plasma membrane stability 
through phospholipid interaction. Proline also serve as a quencher of hydroxyl radical 
and provide energy in the form of nitrogenous source. Moreover, production of 
proline is also linked to water stress, salinity and other abiotic plant stresses (Ashraf 
and Harris, 2004; Munns and Tester, 2008, Lu et al., 2009) indicating an essential role 
for these solutes in tolerance to these stresses. Proline accumulates under salt stress in 
both leaf and root tissues (Sleator and Hill, 2002) and putatively protects against the 
osmotic potential (Watanabe et al., 2000, Chen et al., 2007). Porgali and Yurekli 
(2005) observed that proline level increased in Lycopersicon esculentum showing salt 
sensitivity as compared to Lycopersicon pennellii which was salt tolerant. They also 
suggested the proline level to be a criterion in the evaluation of plants salt stress 
tolerance. Huang et al. (2009) observed that increasing salt concentration increases 
the production of proline in cucumber plant cells and also improve relative water 
contents and peroxidase activity in cucumber leaves.
2.3.2.1.2. Glycine betain (GB) 
Plants initiate some defensive machinery in order to cope with stress; one of them 
is associated with changes in metabolites. Under saline conditions, plants synthesize 
another organic osmolytes of great importance i.e. glycinebetaine (GB). GB helps to 
eliminate the salt stress by regulating the water potential of plant cell. Even the foliar 

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application of GB improves plant growth under salt stress. This response was 
observed in Oryza sativa (Harinasut et al., 1996) and Zea mays (Yang and Lu, 2005).
GB also plays a vital role in transduction of stimuli and homeostasis of certain 
ions (Tuteja, 2007) during plant growth in salty conditons. Cha-um et al. (2006) 
investigated that high level of glycine betain in salt-tolerant rice (Oryza sativa L. spp. 
indica) played a significant part by stabilizing chlorophyll pigments and through 
oxidation of water molecule in PSII. Meloni and Martinez, (2009) observed that in 
vinal (Prosopis ruscifolia Griesbach) increased GB also increased the activity of SOD 
and improved ion homeostasis in high salt concentration. Similarly, Zhang et al. 
(2009) observed over accumulation of GB as salt tolerant mechanism in transgenic 
cotton which also protected plasma membranes and enhanced photosynthesis in 
cotton.