Isolation and Characterization of Spore Associated Bacteria (SAB) From Rhizophagus irregularis and their Effect on Micropropagatedsugarcane Plantlets
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Date
2018-09
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University of Agricultural Sciences, Dharwad
Abstract
An investigation was carried out to isolate spore associated bacteria (SAB) of Rhizophagus irregularis. Out of twenty two SAB isolates, five were selected based on their ability to influence the mycorrhizal parameters like sporulation and percent root colonization.
Selected SAB isolates were characterized and tested for their functional traits such as production of indole acetic acid, gibberlic acid, cytokinin, siderophore, P-solubilisation, ACC deaminase and antagonistic activity against Colletotrichum sp. Results revealed that all the selected SAB isolates were positive for IAA, cytokinin and GA ranging from 10.27 to 17.04 µg /ml of culture filtrate; 0.53 to 3.87 µg /ml of culture filtrate and 3.40 to 8.24 µg /25ml of culture filtrate respectively. All the selected SAB isolates showed positive for ACC deaminase activity, two isolates possessed mineral phosphate solubilization activity and four isolates were found to be antagonistic against Colletotrichum sp.
Nursery studies have indicated that the dual inoculation of Rhizophagus irregularis and SAB consortium significantly increased relative chlorophyll content, plant growth under and improved survivability of micropropagated sugarcane plantlets. Results of the field experiments have revealed that the precolonised seedlings with AMF and SAB recorded the highest plant height, relative chlorophyll content, enzymatic activity, mycorrhizal parameters, biophysical parameters and P content over uninoculated control.
The SAB isolates were authenticated by amplifying 16S rRNA gene sequence. The blast results have clearly indicated that the SABNA2, SABNA9, SABNG12, SABNG14 and SABLG19 were very close to uncultured Bacillus sp., Burkholderia lata, Sphingomonas sp., Mesorhizobium amorphae and Klebsiella pneumonia respectively.