Cross-competence and affectivity of maize rhizosphere bacteria Bacillus sp. MT7 in tomato rhizosphere

Abstract

ABSTRACT Rhizosphere supports the growth and activity of an enormous and diversified microbial network. Certain rhizobacteria referred to as ‘plant growth-promoting rhizobacteria’ (PGPR) can contribute towards improved plant growth and stress tolerance and are currently of great interest for sustainable agriculture. A successful PGPR is capable of establishing itself in the rhizosphere of inoculated plants. Root colonization is an essential step in the interaction amongst plant-associated bacteria and host plant and is a multifaceted phenomenon governed by various biotic and abiotic factors. In the present investigation, an isolate MT7 obtained from maize rhizosphere and identified as Bacillus sp. was tested for its ability to perform in the tomato rhizosphere. It was screened for its survival under various abiotic stresses like salt, drought, heavy metals, and temperature and found to tolerate 10% salt stress, drought stress up to -0.73 MPa (25% PEG), heavy metals like Cr, Cu, and Ni above the permissible limits and grew well from 25 to 45 °C. The bacterial culture was verified for various other plant growth-promoting traits. It expressed chemotactic behavior and good biofilm-forming potential in the presence of tomato root exudates. Profuse colonization was observed on the tomato roots. Efficacy of the bacterial culture in the tomato rhizosphere was evaluated under net house conditions. The tomato crop was positively influenced by inoculation of MT7 over the un-inoculated plants. Therefore, it is concluded that competent colonization by MT7 lies in its ability to respond to tomato root exudates, form biofilms, establish and proliferate in the tomato rhizosphere and express various PGP traits that cause an increase in plant growth. The results indicate the potential of MT7 as a bio-inoculant for tomato.