ISOLATION AND SCREENING OF PHYTOHORMONES PRODUCING PGPR FROM COTTON PLANT RHIZOSPHERIC SOIL

Abstract

Plants are subjected to various abiotic stresses, such as drought, extreme temperature, salinity, and heavy metals. Plants employ several tolerance mechanisms and pathways to avert the effects of stresses that are triggered whenever alterations in metabolism are encountered. Phytohormones are among the most important growth regulators; they are known for having a prominent impact on plant metabolism. PGPR, root - associated rhizobacteria that produce phytohormones may prove to be important for plant growth. In our study, cotton (Gossypium hisrsutum) samples were collected from four different sampling sites rhizospheric soil (rhizosphere, rhizoplane, endorhizosphere) from agriculture farm, cotton research centre, Surat, Gujarat. Out of 81 rhizobacteria from wild and transgenic cotton rhizospheric soil, we isolated 16 IAA, 11 gibberellins and 8 ACC deaminase producing PGPR. Sphingomonas pseudosanguinis strain G1-2, Bacillus circulans strain NBRC 13626, Stenotrophomonas rhizophila strain e-p10with ACC deaminase is balancing ethylene level in stress condition. Other hormones were used in every stages of plant growth. Pseudomonas species, produced highest IAA (0.059 mg/ml) and gibberellic acid (0.53mg/ml). They help in increasing the shoot and root length. So, rhizobacteria play a vital role in the stimulation of plant growth and defense response mechanisms.