CHARACTERIZATION OF ENDOPHYTIC BACTERIA FOR THEIR BIOSTIMULATION AND BIOCONTROL ACTIVITIES ON SUGARCANE (Saccharum officinarum) CROP
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Date
2022
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DRPCAU, PUSA
Abstract
Endophytic bacteria colonizing internal parts of the plants and benefit the crop plants by enhancing their growth and development. These beneficial organisms are documented in almost all plants. Sugarcane also colonizes diverse endophytic bacteria and these bacteria benefit the Sugarcane crop through biostimulation and biocontrol activities. Therefore, a study was conducted to examine the isolated endophytic bacteria of different parts of two Sugarcane varieties, BO-91 and Co-P 16437 for their biostimulation and biocontrol activities. For this, 86 endophytic bacterial isolates, 50 isolates of BO-91(BR 1 - BR25, BS1 - BS 14 and BL1 - BL11) and 36 isolates of CoP-16437 (CR1-CR21, CL1-CL2 and CS1-CS1) collected from Department of Microbiology, CBS&H, Dr. RPCAU, Pusa. These isolates were subjected for morphological characterization on the basis of colony morphology and microscopic features. Most of the bacterial colonies were of small size, circular shape with regular margins, smooth texture and yellow or orange color colonies. These isolates were also subjected for Gram staining and endospore staining and found that 49 isolates as gram-negative, 27 isolates as gram positive and 23 bacteria were endospore producers. The endophytic bacteria were further examined for biostimulaion activities viz, phosphorus (P), potassium (K), zinc (Zn) and Fe solubilization and siderophore,
IAA production. It was observed that 19 isolates of BO-91 and 7 isolates of Co-P 16437 solubilized phosphorus with P-SI (2.2 - 4.1), P-SE (122.7 - 309.1%) and P solubilization value (0.74 - 1.31ppm) whereas 7 isolates of BO-91 and 7 isolates of Co-P 16437 solubilized potassium with K-SI (2.0 - 3.8), K-SE (178.6 - 282.4%) and K solubilization value (14.17 – 15.87ppm). 13 isolates of BO-91 and 7 isolates of Co-P 16437 solubilized zinc with Zn-SI (2.0 – 4.5), Zn-SE (103.4 - 350 %) and Zn solubilization value (3.85 – 1.75ppm) whereas 36 isolates of BO-91 and 20 isolates of Co-P 16437 solubilized Fe with Fe-SE (109.5 – 369.2 %) and Fe solubilization value (0.92 – 2.93ppm). It was also found that 11 isolates of BO-91 and 5 isolates of Co-P 16437 produced IAA (37.22 - 96.51μg mg-1 protein). The isolates BL1, BR2, BR11, BS9 and CR16 showed a positive response for almost all the biostimulation activities. Further, these endophytes were subjected for biocontrol and antagonistic properties viz, ammonia, HCN, cellulase and catalase enzyme production and tested in vitro inhibition against the red rot pathogen (Colletotrichum falcatum). 30 isolates of BO-91 and 30 isolates of Co-P 16437 were able to produce ammonia (0.49 – 1.28ppm), 16 isolates from BO-91 and 11 isolates from Co-P -16437 showed HCN production activity, 31 isolates from BO-91 and 11 isolates from CoP-16437 showed cellulase enzyme production activity in terms of hydrolysis capacity (2.0 – 9.75) whereas 8 isolates from BO-91 and 16 isolates from CoP-16437 showed catalase enzyme production activity. Out of 86 isolates, only 37 bacterial isolates were able to show inhibitory action (49.7– 84 %) against the fungal pathogen. The isolates BR11, CR12, CR20 and CS2 showed a positive response for almost all the biocontrol characteristics with more than 50% of inhibition index of Colletotrichum falcatum. The isolates BR2 (Microbacterium arborescens), BS12 (Bacillus paranthracis/ Bacillus nitratireducens), BS21 (Micribacterium ginsengiterrae), CR7 (Glutamicibacyer halophytocola), CS3 (Bacillus tequliensis) identified as promising endophytic bacteria which showed both biostimulation and biocontrol activities. Therefore, these endophytic bacteria can be used as multitasking strains for biofertilizer and biocontrol agents which help in sustainable production of sugarcane.