Molecular studies on Piriformosrpoa indica and Azotobacter chroococcum interaction

Abstract

Stable cooperation among microbial partners are comparatively unexplored as their mutual responses are difficult to observe. Once functionally diverse microorganisms have been assembled in the rhizosphere, it is important to identify the factors involved in the formation of stable yet dynamic communities. In this dissertation, we have tried to develop an understanding of the formation of stable microbial assemblages in the rhizosphere system and their influence on plant fitness and productivity. Rhizospheric microorganisms like Piriformospora indica and Azotobacter chroococcum are well known for their beneficial interaction with plants. These features make P. indica /A. chroococcum co-inoculation of crops most promising with respect to sustainable agriculture and to understanding the transitions in the evolution of rhizospheric microbiome. Here, we investigated interactions of P. indica with A. chroococcum in culture. Out of five Azotobacter strains tested, WR5 exhibited growth-promoting while strain M4 exerted growth-inhibitory effect on the fungus in axenic culture. 2-D gel electrophoresis followed by mass spectrometry of P. indica cellular proteins grown with or without WR5 and M4 showed differential expression of many metabolic proteins like enolase-I, ureaseD, the GTP binding protein YPT1 and the transmembrane protein RTM1. Interaction of WR5 with P. indica in presence of Arabidopsis thalina(Columbia ecotype-1)led to improved mycorrhizal potential of the fungus further stabilizing A. thaliana- P. indica association by improving reciprocal nutrients exchange. newline