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

growth under heavy metal stress by producing antioxidant enzymes, IAA,

and ACC deaminase (Kumar et al., 2019). The overall mechanisms of abiotic

stress tolerance in plants by PGPR are summarized in Figure 3.4.

FIGURE 3.4 PGPR-mediated stress tolerance in plants.

3.5.1.1 PGPR-MEDIATED DROUGHT TOLERANCE IN PLANT

Among different abiotic stresses, drought stress have several negative

impacts on plants, and it is one of the main factors that only inhibit growth

but also responsible for oxidative damages. Though modern biotechnological

techniques improved plant resistance to drought by producing transgenic

crops but still growth promoting rhizobacteria plays a pivotal role during

the stress period. In drought scenario, the main problem in the plant body

is the production of ROS and ethylene which limits root growth leading to

impaired nutrients uptake. As PGPR has the ability to produce ACC deami­

nase and antioxidant enzymes thus it can inhibit the negative impact and

permits continue growth (Kumar et al., 2019). Pseudomonas fluorescens

when inoculated in Catharranthus roseus it improved drought resistance and

also increased secondary metabolites contents (Nadeem et al., 2013). Simi­

larly, in pea plants PGPR induced drought tolerance through the activity of