List of antagonistic bacterial isolates identified by homology search ofsequences of 16SrDNA by BLAST program obtained from plant samples collected in boro season 2018.
Rice is an important cereal worldwide and it occupies the top position among the cereals in Bangladesh. Rice plant suffers from around 32 diseases of which ten are major in Bangladesh at present. Among the diseases, Bacterial Blight (BB) caused by X. oryzae pv. oryzae (Xoo) considered as a most destructive disease occurs in both rainfed and irrigated seasons of Bangladesh. BB causes considerable yield loss varies from 30 to 50% depending on the outbreak. It is also an important disease in most of the South and Southeast Asian countries. To develop environment-friendly sustainable management approach against BB of rice, in total sixty three plant growth promoting bacteria were identified from rice phylloplane and rhizosphere that are antagonistic to X. oryzae pv. oryzae during boro and aman seasons 2018 and 2019.These bacterial species inhibited the growth of X. oryzae pv. oryzae in vitro by 20.83 to 76.19%. These bacterial isolates were identified by sequencing of PCR products of 16SrDNA belonging to the genera mostly Pseudomonas, Bacillus and Serratia. Out of these bacterial species, 48 bacterial species were found as positive for IAA production, all 63 bacterial species were found positive for siderophore production and 48 were found capable to solubilize insoluble phosphate. Based on growth inhibition of X. oryzae pv. oryzae in in vitro, thirty two bacterial species were selected for plant growth promotion assessment and evaluation of net house and field efficacy in controlling BB of rice. These bacterial species were formulated using talcum powder which was viable for at least three months post formulation. Assessment of plant growth promoting determinants revealed that all 32 bacterial species identified in this study enhance the growth of rice plants as measured by root and shoot length and and reduced the BB severity in susceptible rice cultivar significantly as compared with untreated control.
- Plant growth promoting phylloplane and rhizospheric bacteria
- X. oryzae pv. oryzae
Chemical fungicides (copper compounds, other chemicals and antibiotics) are not effective in controlling this disease . However, control measures are including chemical, cultural, host resistance, genetic modification methods, among them cultural practices are not also effective in all circumstances as well as no fruitful chemical control and commercial product was found in this tropical climatic area which can be suppressed this disease nicely [18, 19]. Moreover, using antibiotics, toxic residues and chemicals have several limitations against BB of rice . Apart from that, the uses of host resistance genes are used, in case of breeding single gene (Xa4) are manifested ineffective BLB management due to sub-populations .
Thus, biological control alleviates costs and it also serves as an environment friendly approach to mitigate this devastating threat , besides, the application of biological strains of PGPB would be the fullest alternative way of minimizing chemical pesticides, fertilizer and environmental pollution . PGPB plays a crucial role in developing immunization in plants body, ISR is triggered by PGPB which is a signaling pathway while SAR mainly dependent on salicylic acid triggering a induced resistance by a particular infection, However, it is observed that ISR requires salicylic acid (SA) and ISR demands ethylene (ET) and jasmonic acid (JA) signal pathways  and both of these are triggered latent resistance mechanism subsequently after inoculation . In recent years, application of PGPB in the field has been evaluated as an inducer showing systematic resistance [26, 27, 38]. Due to fruitful leaf colonization, quick growth, normal application procedure of
Species such as
2. Materials and methods
2.1 Isolation and identification of bacteria from rice phylloplane and rhizosphere
2.1.1 Plant sample collection
To isolate the bacteria from rice phylloplane and rhizosphere, the healthy rice plants with root system and soils of different rice cultivars were collected from 40 districts representing 30 Agroecological Zones (AEZs) of Bangladesh from the vicinity of BB infected rice plants during boro and aman season, 2018 and 2019 at maximum tillering stage to pre-ripening stage. Then the rice plant samples were brought into the laboratory in labeled polybags.
2.1.2 Isolation and purification of bacteria
The phylloplane bacteria were isolated using washing method. Freshly harvested 2nd, 3rd, 4th leaves were vortexed in sterile saline solution for 12 minutes with two or three brief intervals. Then 100 μl solution was placed at the center of Luria Bartani (LB) or King’s B agar plate and the solution was spread with glass spreader. The inoculated plates were incubated for 3–5 days at room temperature. After incubation of the inoculated plates, bacterial colonies appeared with various types of colors. Then the bacterial colonies were selected and isolated depending on their color and were streaked on LB media separately. Again the streaked LB plates were incubated at room temperature for 2 days. For isolation of antagonistic bacteria from rhizosphere, 1 g roots with rhizospheric soils were taken and then it was shaken with 100 ml sterile water for about 10–15 min to obtain soil suspension. Isolation of bacteria were carried out from rhizospheric soil by serial dilution technique up to 10−5 to 10−6 using LB (Luria Bertani) medium. Then the solution was placed at the center of Luria Bartani (LB) or King’s B agar plate and the solution was spread with glass spreader. The inoculated plates were incubated for 3–5 days at room temperature. After incubation of the inoculated plates, bacterial colonies appeared with various types of colors. Then the bacterial colonies were selected and isolated depending on their color and were streaked on LB media separately. Again the streaked LB plates were incubated at room temperature for 2 days.
2.2 Assay of antagonism of bacterial spp. to
X. oryzaepv. oryzaeby dual culture method
Antimicrobial activity of antagonistic strains of
2.3 Assessment of plant growth promoting determinants of bacteria antagonistic to
X. oryzaepv. oryzae
Active isolates with antagonistic potential against
2.3.1 Assay for siderophore production
Siderophore productions by antagonistic bacterial isolates were tested qualitatively as described by Alexander and Zuberer . 5 μl of antagonistic bacterial cell suspension (5 × 108 CFU/mL) was spot inoculated on Chrome azurol S (CAS) agar plate. The plates were then incubated at 30°C for 5 days. Development of yellow-orange halo zone around the bacterial growth was considered as positive for siderophore production. Experiment was performed with a completely randomized design with 3 replications. CAS agar was prepared from 4 solutions. Solution 1 (Fe-CAS indicator solution) was prepared by mixing 10 mL of 1 mmol L−1 FeCl3.6H2O (in 10 mmol L−1 HCl) with 50 mL of an aqueous solution of CAS (1.21 g L−1). The resulting dark purple mixture was added slowly with constant stirring to 40 mL of aqueous solution of hexadecyl trimethyl ammonium bromide (1.821 g L−1). The yielded of dark blue solution which was autoclaved, then cooled to 50°C. The entire reagent was freshly prepared for each batch CAS agar. Solution 2 (buffer solution) was prepared by dissolving 30.24 g of piperazine-N, N-bis (2-ethane sufonic acid) (PIPES) in 750 mL of salt solution containing 0.3 g K2PO4, 0.5 g NaCl and 1.0 g NH4Cl. The pH was adjusted to 6.8 with 50% (w/v) KOH, and water was added to bring the volume 800 mL. The solution was autoclaved after adding 15 g of agar then cooled to 50°C. Solution 3 contained 2 g glucose, 2 g mannitol, 493 mg MgSO4.7H2O, 11 mg CaCl2, 1.17 mg MnSO4.2H2O, 1.4 mg H3BO3, 0.04 mg CuSO4.5H2O, 1.2 mg ZnSO4.7H2O, 1.0 mg NaMoO4.2H2O in 70 mL water, autoclaved, cooled to 50°C. Solution 4 was 30 mL filter sterilized 10% (w/v) casamino acid. Finally, solution 3 added to solution 2 along with solution 4, solution 1 was added last, with sufficient.
2.3.2 Assay for indole acetic acid (IAA) production
IAA production of antagonistic bacterial isolates were carried out as per the procedure described by Patten and Glick . Every isolate was grown in LB media supplemented with (0.005%) L-tryptophan and incubated in shaker at 30°C with 160 rpm for 48 h. Then bacterial culture was centrifuged at 8000 rpm for 15 min and 1 mL culture filtrate was mixed with 4 mL salkowski’s reagent (1.5 mL FeCl3.6H2O 0.5 M solution in 80 mL 60% H2SO4) and the mixture was incubated at room temperature for 30 min, presence of pink color indicate qualitatively that isolate produced IAA. Formation of pink color indicated the presence of indoles .
2.3.3 Phosphate solubilization assay by antagonistic bacterial isolates
Phosphate solubilization was determined according to the method of Azman et al. . Sterile filter papers (5.0 mm) were soaked in antagonistic bacterial cell suspension (5 × 108 CFU/mL) was dispensed using pipette onto sterile filter paper (6.0 mm) that was placed on National Botanical Research Institute’s phosphate (NBRIP) agar plate (Glucose (10 g/L), Ca3 (PO4)2 (5 g/L), MgCl2.6H2O (5 g/L), MgSO4.H2O (0.25 g/L), KCl (0.2 g/L), (NH4)2SO4 (0.1 g/L), Bacteriological Agar (15 g/L) . The plates were then incubated at 28°C for 7 days. Phosphate solubilization was assessed by observing the clear halo zone. The experiment was performed with a completely randomized design (CRD) with 3 replications.
2.4 Identification of selected plant growth promoting antagonistic bacterial isolates by sequence analyses of 16SrDNA
2.4.1 Extraction of genomic DNA
Bacterial culture from NA media was transferred in LB broth and shaken for 18 h at 28°C. Then genomic DNA of antagonistic bacteria was extracted according to Wizard® Genomic DNA purification Kit (Promega, Madison, USA). Obtaining the DNA pellet was rehydrated by adding 25 μL DNA rehydration solution and kept it overnight at 4°C. Finally the genomic DNA samples of the isolates were preserved at −20°C for further use.
2.4.2 Primers and PCR conditions
To identify the antagonistic bacterial isolates, the primer sets 27F (5′-AGA GTT TGATCM TGG CTC AG-3′) and 1518R (5′-AAG GAG GTG ATC CAN CCR CA-3′) specific to 16SrDNA were used for amplification of 16SrDNA from the prepared genomic DNA template . The PCR conditions were as follows: initial denaturation at 95°C for 5 min, 35 cycles denaturation at 94°C for 1 min, annealing at 55°C for 1 min, extension at 72°C for 2 min and finally a 7 min extension at 72°C. PCR products were visualized by electrophoresis on 1.0% agarose gel containing 0.5% of ethidium bromide using a Gel documentation System after separating the PCR products in the agarose gel for 50 min at 80 volt.
2.4.3 Sequencing of PCR products
A partial nucleotide sequencing of 16SrDNA was performed from amplified PCR products using primers 27F (5′-AGA GTT TGATCM TGG CTC AG-3′) in the Macrogen Lab, South Korea via Biotech Concern Bangladesh. The sequencing was done directly from PCR products according to the standard protocols for the ABI 3730xl DNA genetic analyzer (Applied Biosystems, Foster City, CA, USA) with BigDye® Terminator v1.1 and 3.1 Cycle Sequencing Kits.
2.4.4 Processing of sequence data
The sequencing data were processed and nucleotide sequence data was exported using Chromas software version 2.6.4.The quality of nucleic acid sequences was evaluated using Chromas (Version 2.6) software to avoid the use of low quality bases.
2.4.5 Analyses of nucleotide sequences
The nucleotide sequences were analyzed using online bioinformatics tools. The DNA sequences of 16Sr DNA of the bacterial isolates were compared with 16Sr DNA of the bacterial spp. and the sequences of ITS region of the fungal isolates were compared with ITS region of the fungal spp. that were available in the NCBI database using Basic Local Alignment Search Tool (BLAST) algorithm to identify closely related sequences (https://blast.ncbi.nlm.nih.gov/Blast.cgi).
2.5 Formulation of plant growth promoting antagonistic bacterial species
The pure cultures of thirty two selected potential bacterial antagonists were grown on LB agar medium for 24 hrs. Then the bacterial isolates were transferred in LB broth for about six hours by taking a loopful of bacteria from the LB agar plate. After that the liquid culture was then centrifuged and resuspended the pellet in previously prepared 200 ml peptone broth aimed to fortify the carrier materials. This culture broth was then grown for another two hours with shaking. After that 5 ml of sterile 100% glycerol was added to this 200 ml culture. Then the cultures of the bacterial antagonists (200 ml fortified with 1% peptone and 1% glycerol) were added to the mixture of 500 g talcum powder amended with 5 g carboxy methyl cellulose (CMC) and 7.5 g Calcium carbonate which were autoclaved for two consecutive days at 121°C under 15PSI pressure for 30 min each. The formulations were then being dried overnight in the tray. After that the formulations were powdered with hand, the formulated bacterial antagonists were packed in plastic bags. The formulated bacterial antagonists were then kept at both room and 4-8°C temperature in the refrigerator.
2.6 Assessment of viability of the formulated fungal and bacterial antagonists
The viability of the bacterial and fungal antagonists were checked by drawing 1 g of the formulated products in sterile water in every 30 days after formulation and diluted serially up to 10−4 or 10−5. The numbers of viable cells (colony forming unit) were counted per gram formulations kept at both room temperature and 4-8°C temperature in the refrigerator.
2.7 Assessment of plant growth promotion induced by antagonistic bacterial and fungal isolates
Rice seeds (cv.IR24) were surface sterilized and dried. Then the sterilized rice seeds were treated with formulated bacterial and fungal antagonists (10 g/kg seeds) and the treated seeds were left for 1 h under shade. The rice seeds were then sown in the plastic pots previously filled with sterile soils. Fifty seeds were sown in each pot and three replications were maintained. Then the germination of seeds were recorded at 7DAS. The seedlings were uprooted at 7 DAS, 14 DAS and 28 DAS to measure the root length, shoot length and to calculate the vigor index [= (root length + shoot length) × germination percentage] were measured.
2.7.1 Seed priming, raising of seedlings and transplanting
Seeds of IR24 were treated with 32 selected formulated PGP antagonistic bacterial isolates. The treated sees were left for 1 hr. for adherence of the bacterial and fungal isolates with the treated seed surface. The treated seeds were then sown in the plastic pots filled with sterilized soils. One month old seedlings were then transplanted in the plastic pots filled with puddle soils.
2.7.2 Foliar spray of formulated PGP bacterial and fungal isolates
Formulated PGP antagonistic bacterial isolates were sprayed two times (at 50 and 55 DAS) before inoculation and two times after inoculation i.e. 65 and 70 DAS.
2.7.3 Inoculation of the rice plant with
X. oryzaepv. oryzae
Rice plants were inoculated with a strain of
3.1 Isolation and identification of antagonistic bacteria against
X. oryzaepv. oryzae
Rice plant samples were collected from 40 districts of Bangladesh representing 30 AEZs during boro seasons 2018–2019 and aman seasons 2018–2019. In total 300 bacterial isolates and 100 fungal isolates were isolated and purified from rice plant samples during boro season, 2018. Some selected representative bacterial species were shown in Figure 1. Out of 300 bacterial isolates, eighteen were identified as antagonist against
|Isolates||Closest relatives||Accession no.||Alignment||Homology||Growth inhibition of |
|Isolate ID||Closest relatives||Accession no.||Alignment||Homology||Growth inhibition of |
|Isolate ID||Closest relatives||Accession no.||Alignment||Homology||Growth inhibition of |
|Isolate ID||Closest relatives||Accession no.||Alignment||Homology||Growth inhibition of |
3.2 Assessment of plant growth promoting determinants
Three plant growth promoting determinants viz. siderophore and IAA production as well as phosphate solubilization capability were assessed. The results revealed that the development of yellow-orange halo zone around the bacterial growth on chrome azurol S agar plates was considered as positive (+) for siderophore production, formation of pink color by the culture supernatant of the bacterial isolates in presence of Salkowski’s reagent confirmed IAA production which was indicated by ‘+” sign and observation of clear halo zone in National Botanical Research Institute’s phosphate (NBRIP) agar plates indicated the bacterial isolates are capable of phosphate solubilization which was denoted by “+” sign (Figure 3). Out of these bacterial species, Out of these bacterial species, 48 bacterial species were found as positive for IAA production, all 63 bacterial species were found positive for siderophore production and 48 were found capable to solubilize insoluble phosphate. In case of Indole Acetic Acid (IAA), BDISOB92FarR (
3.2.1 IAA production
In case of Indole Acetic Acid (IAA), four isolates those were BDISOB92FarR (
|Treatments/bacterial isolates||Name of bacteria||Indole acetic acid (IAA) (ng/ml)||Siderophore production (orange color halo zone) (mm)||Phosphate solubilization (clear halo zone) (mm)|
|Control||—||0.00 o||0.00 h||0.00f|
|BDISOB283KisR||43.90 l||18.33bc||8.33 cd|
|BDISO04DinP||46.59 k||13.00 fg||8.17 c-e|
|BDISO135SerP||67.80 h||10.83 g||8.33 cd|
|BDISOB92FarR||82.68a||0.00 h||7.50 c-e|
|BDISOB21ChaR||78.78b||11.17 g||7.00 c-e|
|BDISOB86FarR||68.93 h||18.33bc||7.33 c-e|
|BDISOB46GopR||71.89 cd||20.00b||7.17 c-e|
|Level of significance||*||*||*|
3.2.2 Siderophore production
Six bacterial isolates BDISOB222GaiR (
3.2.3 Phosphate solubilization
Among all bacterial isolates three of them those were BDISOB05MymP (
3.3 Plant growth promotion by bacterial isolates antagonistic to
X. oryzaepv. oryzae
Based on the growth inhibition of
|Treatments||Root length (cm)||% Increase of vigor index over control||Shoot length (cm)||% Increase of root length over control||Vigor index||% Increase of shoot length over control|
|Days after sowing (DAS)|
3.4 Plant growth promotion by different bacterial isolates antagonistic to
3.4.1 Fresh shoot weight
At 28 days after sowing the highest shoot weight (2260 mg) was recorded in plants raised from the seed treated with the bacterial isolate BDISOB01MymR followed by the bacterial isolates BDISOB05MymP (2250 mg), BDISOB45PanP (2173 mg), BDISOB04DinP (2033 mg), BDISOB86FarR (2033 mg), BDISOB07FarR, (2033 mg) BDISOB283KisR (1950 mg). But the lowest shoot weight was observed in control (untreated seed) (933 mg) Rest of the isolates were showed moderate fresh shoot weight. Among all bacterial isolates seventeen were statistically similar and others denoted statistically dissimilar (Table 7).
|Treament||Isolate ID||Fresh shoot weight (mg)||Dry shoot weight (mg)||Fresh root weight (mg)||Dry root weight (mg)|
|To||Control||—||933.33 k||333.33d-g||830.00 g||170.00 l|
|T1||Positive control||—||1300.00j||360.00 cd||1016.67ef||220.00jk|
|T4||BDISOB219GaiR||1816.67d-i||410.00b||983.33 fg||246.67 hi|
|T17||BDISO158ChaR||1763.33d-i||293.33 h||1180.00a-f||246.67 hi|
|T22||BDISOB17CumR||2066.67a-d||363.33 cd||1220.00a-d||310.00 g|
|T25||BDISOB30ChaR||1733.33e-i||363.33 cd||1080.00d-f||266.67 h|
|T32||BDISOB70KusR||1566.67 h-j||363.33 cd||1113.33c-f||233.33i-k|
|T33||BDISOB172ThaR||1510.00ij||360.00 cd||1160.00a-f||246.67 hi|
|Level of significance||—||—||*||*||*||*|
3.4.2 Dry shoot weight
At 28 days after sowing the highest shoot weight (546 mg) was recorded in plants raised from the seed treated with the bacterial isolate BDISOB01Mym
3.4.3 Fresh root weight
At 28 days after sowing the highest rootweight (1350 mg) was recorded in plants raised from the seed treated with the bacterial isolate BDISOB45PanPfollowed by the bacterial isolates BDISOB05MymP (1316 mg), BDISOB21ChaR (1306 mg) BDISOB15CumR (1256 mg), BDISOB01MymR (1253 mg), BDISOB92Far (1246 mg), BDISOB16CumR (1213 mg) were statistically similar Whereas, the lowest (830 mg) was recorded in the plants raised from untreated seed followed by thebacterial isolate BDISOB219GaiR (983 mg), plants sprayed with [Bactroban (inducer) + SICOGREEN® (nutrient and hormonal solution) + Hemoxy (Copper fungicide)] (1016 mg), BDISOB30ChaR (1080 mg). Other bacterial isolates were statistically similar (Table 7).
3.4.4 Dry root weight
At 28 days after sowing the highest dry root weight (450 mg) was recorded in plants raised from the seed treated with the bacterial isolateBDISOB01MymR, BDISOB222GaiR (440 mg) followed by the bacterial isolates BDISOB05MymP (413 mg), BDISOB04KhaP (403 mg). Whereas, the lowest (170 mg) was reorded in the plants raised from untreated seed followed by the plants sprayed with [Bactroban (inducer) + SICOGREEN® (nutrient and hormonal solution) + Hemoxy (Copper fungicide)] (220 mg), BDISOB54KhuR (213 mg). Other bacterial isolates were statistically similar (Table 7).
3.5 Effect of some selected antagonistic bacterial isolates on the reduction of lesion length in susceptible check cultivar (IR24) caused by
X. oryzaepv. oryzae
To evaluate the mechanisms of BB severity reductionby plant growth promoting antagonistic bacteria, susceptible check variety IR24 was used. The results of plant inoculation showed a significant reduction of lesion length in plants sprayed with formulated bacterial bioagents as compared with untreated control.
(Table 8). 96.56% reduction of lesion length was marked as highest spraying with BDISOB222R followed by BDISOB05P (95.71%), BDISOB283R (94.38%), BDISOB21R (93.80%), BDISOB258R (93.61%), BDISOB04P (92.61%), BDISO45P (91.55%) and BDISO1R (90.16%). The minimum (50.145%) reduction of lesion length were observed in plants sprayed with BDISO158R followed by BDISO198P (52.36%) and BDISOB15R (54.03%). Ten bacterial isolates were revealed upper-moderate level of lesion length reduction and eleven isolates were marked their place at lower-moderate level of lesion length reduction. However, all other bacterial isolates reduced lesion length significantly as compared with the untreated plants (Table 8 and Figure 5).
|Isolate ID||Name of bacteria||Lesion length* (mm)||Reduction of lesion length (%)|
|Level of significance||*|
Antagonistic bacterial isolates were identified mostly as different species of
Out of the 63 bacterial isolates, 48 bacterial species were found as positive for IAA (Indole Acetic Acid) production, all 63 bacterial species were found positive for siderophore production and 48 were found capable to solubilize insoluble phosphate. IAA also has been speculated to fasten the overall fitness of plant-microbe associations . It was proved that numerous plant-associated bacteria have the ability to produce IAA by stimulating plant roots development and improving absorption of water and nutrients from soil [71, 72]. The IAA producing bacteria encouraged adventitious root formation, produced the greatest roots and shoots weight . All 63 bacterial isolates were found to produce siderophore. When iron availability is in stress microorganism those who produce siderophore supplied Fe nutrition to enhance plant growth . Siderophore also assists when it comes to the growth condition of shoots, roots as well as nutrition in plants . Siderophore plays a crucial role in selecting a potential bioagent , besides, it has been considered as an alternative to ruinous pesticides effects . The biological control mechanism depended on the role of siderophore as competitors for Fe in order to reduce Fe availability for the phytopathogen . Siderophores produced by numerous bacteria had a significant role in the biocontrol and negatively affected the growth of several pathogens [78, 79]. Forty eight bacterial isolates showed the capability of phosphate solubilization. It has been also experimented that phosphate solubilizing bacteria (PSB) can also triggered plant growth promotion . This PSB inoculants have been exploited as a possible alternative for phosphate fertilizers which is inorganic  and it also influences phosphate uptake and plant growth [82, 83]. It has also been documented that the application rates of phosphate fertilizers reduced to 50% by inoculating phosphate solubilizing microbes (PSM) added phosphate fertilizers reduced the disease incidence up to 50% .
Among the bacterial isolates, 32 were selected based on their antagonistic capability and growth promoting determinants. PGPB have significant impact in surging root length, vigor index and shoot length. Sakthivel
Forty eight bacterial species were found positive for phosphate solubilization out of 63 antagonistic bacterial species identified in this study. It has been reported that phosphate solubilizing bacteria (PSB) induced plant growth promotion . Plant roots-associated PSB have been considered as one of the possible alternatives for inorganic phosphate fertilizers for promoting plant growth and yield . Plant growth and phosphate uptake have increased in many crop species due to the results of PSB inoculants [82, 83]. It has also been documented that the application rates of phosphate fertilizers reduced to 50% by inoculating phosphate solubilizing microbes (PSM) in crops without significantly reducing crop yield . In sustainable agriculture, specific plant pathogens can be supressed by biological agents such as plant growth promoting bacteria (PGPB) which can also be used as bio-fertilizer . There are a plenty of PGPB strains that reported to suppress numerous of plant pathogen, reduced disease incidence, triggered plant growth factor and provides nutrition for the growth of the plant [63, 90]. Thus, it has been considerable research interest in the potential use of antagonistic bacteria as PGPB [91, 92]. To evaluate plant-interaction with bacteria, such as endophytes, biocontrol agents, phytopathogens, and symbionts needs to be re-infection and development of those experimental strains in or on field grown plants . Effective root colonization by fluorescent
Thirty two potential bacterial isolates were identified belong to the genera mostly
This research work was carried out with the financial support from National Agricultural Technology (NATP), Phase-2, under Program Based Research Grant (PBRG), Bangladesh Agricultural Research Council (BARC), Farmgate, Dhaka, Bangladesh to Dr. Md. Rashidul Isalm (Grant ID No.: 091).
Conflict of interest
There is no conflict of interest among the authors.