The biotic and abiotic stresses are key constraints for food quality, crop yield and global food security. It is necessary to take action to cope with global threats caused by abiotic and biotic stresses such as a reduction in precipitation, increasing drought, salinity, improper temperature, heavy metals, nutrient deficiency and invasion of plants pathogenic microbes, which lead to the reduction of agricultural crops productivity. Plants are severely affected by these stresses and have impaired functioning. One of the strategies to cope with abiotic and biotic stresses is taking advantage of the potential of soil microbes, including plant growth-promoting rhizobacteria (PGPR). The solution is completely environmentally compatible and has no negative effects on the environment. Effective PGPR have a substantial role in biotic and abiotic stresses management, reduce chemical fertilizers and increase the yield of plant cultivars by affecting elemental cycling and nutrient management. These beneficial bacteria can stimulate plant growth under abiotic and biotic stress conditions via mechanisms such as the production of phytohormones, ACC (1-aminocyclopropane-1-carboxylate) deaminase, exopolysaccharides, siderophore, organic acids, nitrogen fixation, phosphate solubilization, various osmolytes, systemic resistance induction, etc. In this review, the role of the PGPR as a new strategy was investigated that may be responsible for the increase in crop productivity and eventually by effectively answering biotic and abiotic stresses leads to food security.

Vitex negundo L. is an aromatic, woody, blooming shrub in the Lamiaceae family which can grow into a small tree. Traditionally, V. negundo root has been used to cure diabetes, colic, boils, leprosy, and rheumatism. Keeping the importance of its roots in mind, an attempt has been taken for development of a protocol for efficient hairy root proliferation system. The Agrobacterium rhizogenes strains (MTCC 532 and MTCC 2364) were used for hairy root induction. For A. rhizogenes infection, both in vitro and in vivo leaves as well as internodes were used as explant. In vitro leaves and internodal explants were obtained by the inoculation of matured nodal segments on the optimum medium [MS + 2.0 mg/L N6-Benzylaminopurine (BAP)] with c.a. 91.6% shoot regeneration and an average of 8.1 shoots per explants. In vitro leaf showed best hairy root induction followed by in vitro internode on ½ MS medium augmented with acetosyringone. Highest transformation efficiency was achieved using MTCC 2364 strain, while no transformation was observed in MTCC 532 strain. Different factors affecting transformation including co-cultivation period, infection time and optical density (O.D.) value were standardized. The highest efficacy, 88.8% hairy root induction was observed in in vitro leaves infected by MTCC 2364 for 60 minutes infection time with an O.D. value of 0.29 maintained over a 44-48 hours of co-cultivation period. The prescribed protocol may be used as a reference for development of industrial scale hairy root production for bioactive compound located in root of V. negundo.