Smt. Guman Devi Verma Memorial Best Woman Scientist Award- Exploitation of Tea Rhizosphere Microorganism for Improvement of Plant Health Status

摘要

Bacillus megaterium TRS-4 isolated from rhizosphere of healthy tea plants, was found to be antagonistic to several root pathogens viz, Fomes lamaoensis, Porta hypobrumea, Sphaerostilbe repens, Sclerotium rolfsii and Sclerotinia sclerotiorum in vitro.It was also found to exhibit other plant growth promoting and disease suppressing characteristics such as phosphate solubilization, IAA production as well as siderophore production. In vitro bioassay of the active principle extracted from B. megaterium cells inhibited mycelial growth and spore germination of test pathogens. B. megaterium promoted the growth of tea seedlings and two-year-old plants significantly, as evidenced by increased plant height, number of branches and leaves. Bacterization of chickpea seeds also resulted in a significant enhancement of germination and vigour index. Various biochemical changes in tea plants associated with the bacterial inoculation were analysed. Tea leaf catechins extracted from B. megaterium treated plants whenanalysed by HPLC revealed a few new isoforms. In greenhouse tests, treatment of plants with B. megaterium significantly reduced brown root rot of tea caused by F. lamaoensis and stem rot of chickpea caused by S rolfsii. Association of defense related enzymes, mainly, chitinase, beta-l,3-glucanase, peroxidase and phenylalanine ammonia lyase as well as other biochemical components like proteins and phenols were studied on inoculation of pathogen in B. megaterium treated plants. Talc based formulation of B. megaterium was prepared and tested in greenhouse for its growth promoting ability. The survivability of bacteria in talcum formulation in the laboratory and its sustainability in the rhizosphere after its application either as soil drench or in talc formulation were also detected specifically by immunological techniques such as ELISA and -colony transfer using polyclonal antibody (PAb) raised against the bacterium. Further, a reduction in pathogen populations in presence of B. megaterium was detectedby ELISA and Dot-blot using PAb of F. lamaoensis.