Co-inoculation of Fluorescently tagged rhizobacteria in breaching the host specificity in Legumes

Abstract

Rhizobia-legume symbiosis which results in nodule formation is highly specific. Rhizobium species was isolated from Moong bean nodules. Rhizobacterial strains Pseudomonas putida and Klebsiella pneumoniae C3091 were selected for co-inoculation experiment to check their ability to break the host specificity. All rhizobial as well as non rhizobial species were fluorescently tagged with plasmid bearing constitutively expressing GFP, CFP or RFP. Coinoculation studies were done by inoculating root hairs of germinated Moong bean with native Rhizobium together with other Rhizobium and non-rhizobial species. Further analysis was done by observing root hair curling (RHC) within few hours of inoculation and presence of fluorescence within the root hairs under confocal laser scanning microscope was confirmed. The result indicated that rhizobacterial species coinoculated were able to enter the root hair along with Moong bean Rhizobium. Therefore it can be inferred that during RHC, non rhizobial species also get entrapped with rhizobia thereby prevailing their entry inside the root hairs. The fate of these rhizobacteria in infection thread movement and later nodule formation remains to be studied.