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Survey, Collection, Isolation and Identification of Black-rot (xanthomonas Campestris Pv. Campestris) from Cabbage and Cauliflower

K. Jahan
Scientific Officer
Plant Pathology Division, BARI, Gazipur

R. Islam
Scientific Officer
Plant Pathology Division, BARI, Gazipur

T.K. Dey
Chief Scientific Officer
Plant Pathology Division, BARI, Gazipur

Abstract/ Executive Summary:

Around 1-30% and 3-70% black-rot disease were recorded respectively, from cabbage and cauliflower. A total of 34 isolates of bacteria were isolated from black rot symptoms of cabbage and cauliflower. The isolates were tested following Gram reaction, growth on Asparagine medium and Nutrient agar with 5% glucose. Out of 34 isolates five showed Gram positive and rest scored gram negative. Gram negative isolates failed to grow on Asparagine medium which indicated the isolates were belong to genus Xanthomonas. Further biochemical and pathogenicity test are required for confirmation of X. campestris.

Keywords: Bacteria,

Location: BARI, Gazipur

Start Date:

End Date:

Program Area: Pest Management

Commodity: Diseases

Objectives:

To identify and characterize the bacteria Black-Rot of Cabbage and Cauliflower

Methodology:

Samples were collected from different cabbage and cauliflower growing areas of Rajshahi and Pabna. A total of 34 black rot samples were collected from surveyed area of which 15 from cabbage and 19 from cauliflower. Isolation and preservation: From each of the 34 bacterial samples collected a loopful of the suspension was streaked on YPSA plates. The plates were then incubated at 28^OC for 48-72 hours. Bacterial colonies from each plate were further sub-cultured and pure bacterial colonies were transferred to YPSA slants incubated at 28^OC for 48-72 hours and preserved at 4^OC for further work. Morphological and biochemical tests: Gram staining reaction: The Gram-reaction of each isolates was determined following the quick test method by using 3% KOH. First, two drops of 3% KOH were placed at the centre of a clean glass slide. One loopful colonies of each isolates were added to KOH solution and homogenized with rapid circular movement for few seconds. Viscous strand formation was observed and on drawing it with the loop, it formed a fine thread of slime. This indicated that the test was positive and confirmed gram negative nature of the bacterium. On the contrary, the gram positive bacteria did not produce such thread. Growth on Asparagine medium All gram negative isolates were allowed to grow on Asparagine medium at 28^OC for 48-72 hours without any other carbon and nitrogen sources (Bradbury, 1984). Growth on Nutrient Agar with 5% glucose: Each isolates were streaked on nutrient agar with 5% glucose and incubated at 28^OC for 48-72 hours. Mucoid and yellow colony growth on this medium is one of the characteristics that differentiate Xanthomonas campestris from other Xanthomonas spp. (Bradbury, 1984). The growth and colony colour of each isolate was recorded.

Source of Information: Annual Report 2009-10 ,BARI

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

From the survey it was observed that black rot disease incidence is 1-30% for cabbage and 3-70% for cauliflower. Thirty-four bacterial samples collected from infected leaves of cabbage and cauliflower were grown on YPSA plates. Most of the isolates showed mucoid growth with light to deep yellow and creamy colonies. All the isolates were tested for Gram reaction and for growth ability on Asparagine medium. Most of the isolates were found to be gram negative except isolates CI13, CI18, FI1, FI12 and FI15. Among the gram negatives, all the isolates did not grow on Asparagine medium, indicating probability of Xanthomonas. The growth of the isolates on Nutrient agar with 5% glucose medium showed variation in colour and growth character of colonies. Isolates CR4, CR8, CR10, CR12, CR14, CR16, FI4, FI5, FI8, FI10, FI14, FI15, FI4 and FI20 showed deep yellow colony colour with mucoid growth. Isolates FI2, FI12 and FI18 exhibit light yellow colony colour. And rest of the isolates showed creamy to light creamy colony colour

Knowledge Management: Report/Proceedings