Agricultural Research Management Information System

Home
Research Summary
Search
About Us
- ARMIS
- Brochure
Contact Us
Report
User Request
Data Input
Help
- Operation Manual
  - PDF
  - Video
- Program Area & Commodity
We have reached 37600 number of research entries at this moment.

- Logout

Research Detail

Home
Research
Detail

Characterization of Leaf Blight Pathogen, Pseudomonas Syringae Pv. Syringae of Mango in Bangladesh

Islam S.I.A.
Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh-2202, BANGLADESH

Islam M.R.
Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh-2202, BANGLADESH

Dastogeer K.M.G*
Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh-2202, BANGLADESH

Hossain
Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh-2202, BANGLADESH

Abstract/ Executive Summary:

Bacterial leaf blight of mango caused by Pseudomonas syringae pv. syringae is an emerging disease and great threat for production of healthy mango saplings in different nurseries of Bangladesh. A survey was conducted in nurseries of some selected areas viz. Dinajpur, Rajshahi, Khulna, Mymensingh and Madhupur of Bangladesh to know the status of bacterial leaf blight of mango in terms of its incidence and severity and to characterize the pathogen causing the disease. The results showed that the highest (10.42%) bacterial leaf blight incidence was recorded in Rajshahi followed by Mymensingh, Madhupur and Dinajpur with 9.73, 9.12, 8.64 % disease incidence respectively and the lowest (8.58%) incidence was recorded in Khulna. The maximum (7.34%) severity of bacterial leaf blight was recorded in Rajshahi followed by Dinajpur, Mymensingh and Madhupur with 7.17, 7.13, 7.13% disease severity and the minimum (7.03%) severity was recorded in Khulna. Twenty four bacterial isolates were obtained from the infected leaves by tissue planting method from different locations surveyed. Pathogenicity test on detached mongo leaves confirmed the bacterium was Pseudomonas syringae pv. syringae. The hypersensitivity test in tobacco leaves with P. syringae pv. syringae isolates did not show rapid death leaf of tissues where infiltrated. The causal bacterium, P. syringae pv. syringae was also characterized by a series of biochemical tests viz. KOH solubility test, Gram staining test, Kovac’s oxidase test, Temperature sensitivity test, Levan test, Sugar utilization test, Arginine dihydrolase activity, Catalase test and Pectolytic test. The results of the all the tests revealed that the causal organism of leaf blight of mango was Pseudomonas syringae pv. syringae.

Keywords: Characterization, Leaf blight, Pathogen, Mango

Location: Rajshahi, Dinajpur, Mymensingh, Madhupur and Khulna, Bangladesh

Start Date: 00-07-2011

End Date: 00-09-2011

Program Area: Pest Management

Commodity: Mango

Objectives:

A comprehensive survey was made in some nurseries of the selected mango growing areas to know the status of bacterial leaf blight of mango in terms of its incidence and severity in some selected nurseries and to characterize different isolates of its causal organism in Bangladesh.

Methodology:

Survey and collection of diseased plant samples: A survey was carried out to know the status of bacterial leaf blight of mango in nurseries of Rajshahi, Dinajpur, Mymensingh, Madhupur and Khulna during July to September 2011. At least ten nurseries from each growing areas were surveyed to record the bacterial leaf blight incidence and severity. The infected leaf samples from different nurseries were brought into the laboratory for the isolation of the pathogen. Isolation, purification, identification and preservation: The infected leaves were surface disinfected by immersion in 10 % Clorox solution and then rinsed in sterile distilled water. Leaf pieces after drying on blotting paper were transferred to nutrient agar (NA) medium and incubated at 25°C for 2 to 3 days. Bacterial isolates were purified by streaking a single colony of each isolate on NA medium as described by Kelman8 .The isolates of bacteria were preserved in 10% skim milk kept at - 20^oC refrigerator for subsequent biochemical studies. Characterization of Pseudomonas syringae pv. Syringae: Pathogenicity Test: To confirm the isolates of P. syringae pv. syringae, the pathogenicity test was performed on the detached leaves of mango. A single colony of P. syringae pv. syringae showing virulent, fluidal, irregular and creamy white color was selected for each group of isolates and multiplied in a NA medium. After 24 hours bacterial isolates were suspended in sterile water. The tip of the leaves was cut about 2.5cm. Then the cut leaves were dipped into bacterial suspension for 24hr. The inoculated leaves were then incubated in a Petridish at room temperature for at least 5-7days for the appearance of symptom. Host range test: The host range of P. syringae pv. syringae isolates were tested in some other fruit species such as Guava, Jujube and Litchi by pathogenicity test on detached leaves (described earlier) of those fruit species. This test was performed to observe the reaction or infection ability of P. syringae pv. syringae, on fruits other than mango. Hypersensitivity response (HR) test: To determine the pathogenic nature of the isolates, hypersensitive reaction was studied on tobacco (Nicotiana rustica) plants by infiltration of bacterial suspension into the intrveinal areas of the tobacco leaves9 . Biochemical studies for of P. syringae pv. Syringae: Gram staining reaction: 24 hrs old fresh bacterial cultures for each group of isolates were taken to perform the gram reaction test. Bacterial mass were taken out from culture, spread on clean glass slide followed by drying in air without heat and was flamed it lightly and gently to settle the bacteria. Crystal violet was then poured over the bacterial smear on the slide for 2-3 minutes and washed in tap water for 1 minute and lightly blot dry on a paper towel to remove crystal violet. The smear was flooded with iodine solution for 1 minute and washed in tap water for few seconds and then blot dried. It was decolorized with solvent e.g. alcohol, until the solvent flowed colorlessly from the slide (about 2-4 seconds) and rinse in tap water for 5 seconds. Then the smear was counterstained for about 1 minute with safranin solution and washed briefly in tap water followed by blot dry. One drop emulsion oil was then added on the slide and placed it on compound microscope with 100 x magnification for observation. Potassium hydroxide test: Gram staining results were confirmed by potassium hydroxide test (KOH) 3% as described by Suslow et al.10. The bacteria were aseptically removed from Petriplates with tooth pick, placed on glass slide in a drop of 3% KOH solution and stirred for 10 second using a quick circular motion of hand. Oxidase test: A 24h old bacterial colony on nutrient agar, augmented with 1% glucose was used in this test. A loopful of the inoculum was rubbed on filter paper pervaded with 15%(w/v) freshly prepared aqueous solution of Tetramethyl-pphenylene diamine dihydrochloride11 . Temperature sensitivity test: The ability of bacterial isolates to grow at different selected temperature at 27°C, 37°C and 41°C were tested by initially growing isolate on NA for 24h. The bacterial suspension of isolate was prepared from 24 hrs NA culture to 5 ml of nutrient broth. 2-3 drops of bacterial suspension was taken in nutrient broth contained in test tubes which were placed at temperature 27°C, 37°C and 41°C. Levan test: Sucrose peptone agar or a nutrient agar medium with 5% sucrose is suitable substrate for Levan test. For the test a single colony for each isolate was stabbed with a sterilized tooth pick on NA medium containing 5% sucrose. Then the plates were incubated at 28^oC for 2 to 4 days to have distinctive dome shaped colonies. Sugar Utilization test: Preparation of medium: The medium consists of peptone water to which fermentable sugar was added in the proportion of 1%. Peptone water was prepared by adding 1g of Bacto peptone (Difco, USA) and 0.5 g of sodium chloride in 100 ml distilled water. The medium was boiled for 5 minutes, adjusted to pH at 7.0, cooled and then filtered through filter paper. Phenol red, an indicator at the strength of 0.2% solution was added to peptone water and then dispensed 5 ml in Durham's fermentation tubes, placed inversely. These were then sterilized in autoclave at 121^oC maintaining at 15 PSI pressure for 15 minutes. The sugars used for fermentation test were prepared separately as 10% solution in distilled water (10 g sugar was dissolved in 100 ml of distilled water). A little heat was given to dissolve the sugar completely. The sugar solutions were sterilized using filters. An amount of 0.5 ml of sterile sugar solution was added aseptically in each culture tubes containing sterile peptone water and the indicator.

Source of Information: International Research Journal of Biological Sciences Vol. 2(6), 39-45, June (2013) ISSN 2278-3202

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The findings of the study clearly indicated that leaf blight of mango is caused by Pseudomonas syringae pv. syringae which was observed in all nurseries of different locations surveyed. The disease seems a great threat for raising quality and healthy mango saplings in order to get higher fruit production. However, the management strategies still not developed due to lack of the identification of the causal organism. The findings of the present study would definitely be useful to design a International Science Congress Association 45 comprehensive molecular based analysis of the pathogen Pseudomonas syringae pv. syringae and to adopt a proper management strategy suitable for the integrated disease management programs.

Knowledge Management: Journal