48

Biology and Biotechnology of Environmental Stress Tolerance in Plants, Volume 3

result in an elevation in the length of root, its surface area along with number

of roots thereby increasing the uptake of nutrients (Egamberdieva & Kucha­

rova, 2007).

Reduction in recurrence of plant pathogens causing diseases is a primary

indirect factor. Rhizobacteria that colonize the roots create ACC deaminase,

which helps in the conversion of ammonia and alpha ketobutyrate from

ACC, lowering ethylene. Under stress, rhizobitoxine enzyme is known to

inhibit the synthesis of ethylene synthesis, thereby promoting the nodula­

tions. In an attempt to reduce the salt tensity, the PGPB collects osmolytes in

the cytoplasm, thereby creating a counteract to the osmotic stress along with

keeping a check on the turgor pressure of the cell and the plant development.

Salinity resistance of plant is achieved when the EPS binds to the cations,

which explains its unavailability in plants in stress (Vardharajula et al.,

2011). Co-inoculation with the strains of PGPR for example Pseudomonas,

Rhizobium, etc., can help plants flourish in saline soil by overcoming these

negative effects (Bano & Fatima, 2009). PGPR features were found in two

rhizospheric bacteria isolated from saline soil, Bacillus pumilus and Bacillus

subtilis, including IAA synthesis, hydrogen cyanide (HCN) and ammonia

generation, solubilization of phosphates, and salt tensile resistance (Damo­

daran et al., 2013) (Figure 2.1).

FIGURE 2.1 Effect of different biotic and abiotic stresses on plants.

2.5 MYCORRHIZAL FUNGUS IN SALINITY AND DROUGHT STRESS

TOLERANCE

The tolerance to salinity and drought distress is aided by plant-associated

fungus. Drought stress is alleviated by AM symbiosis, which changes

hormone physiology and plant physiology. It also boosts the effectiveness of