Evaluation of the wild type and Tn5::gusA mutants of Enterobacter sp. R29 and Pseudomonas aeruginosa AMAAS57 on growth and yield of groundnut

Abstract

To Evaluate of the wild type and Tn5::gusA mutants of Enterobacter sp. R29 and Pseudomonas aeruginosa AMAAS57 on growth and yield of groundnut. Molecular marker gusA, was introduced into AMAAS57 and Rh 29 and recipients were selected by kanamycin chloramphenicol resistance, respectively. All the mutants were characterized. All the selected 20 gusA mutants isolated were sown with groundnut in pots in triplicates under unsterile soil conditions for studying the nodule occupancy under different salinity induced condition. The study was conducted in Directorate of Groundnut Research, Junagadh in 2010. Molecular marker gusA, was introduced into wild type AMAAS57 and Rh 29. Mutants were characterised and selected for the pot trial with groundnut plant. The plant samples, rhizosphere and rhizoplane soil samples were collected at 45 and 90 DAS for various observations of crop growth and population of gusA tagged mutants. Root and shoot length and biomass; nodule number and dry weight; nodule occupancy by gusA marker; pod yield (g/p), root and shoot dry weight (g/p), etc. were observed. The result showed, with increase in salinity there was decrease in nodule occupancy by R29. However, mutation improved the nodule occupancy at elevated salinity as compared to wild type. Monitoring the population of the wild type and Tn5::gusA mutants of Pseudomonas aeruginosa AMAAS57 and Enterobacter sp. R29 and their mutants in the rhizosphere of groundnut, cultivar GG2 at 0 and 2 EC of salinity revealed that the population of wild type was much lower as compared to mutants without salinity in the rhizosphere at 45 DAS. However, with increase in salinity, the population of the wild type was better. However, there was reduction in the population of mutants. Population of Enterobacter sp. R29 and its mutants were much better in the rhizoplane across salinity and 45 and 90 DAS. There were wide variations in the population of the mutants of Pseudomonas aeruginosa AMAAS57 both in the rhizosphere and rhizpoplane across salinity and maturity of the plant. The variation of the population of the mutants might be due to alternation in the genes responsible for colonization and also in the genes responsible for salinity tolerance in Enterobacter sp. R29 due to insertion of Tn5::gusA..