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Pathogenic Variation in Xanthomonas Oryzae Pv. Oryzae Causing Bacterial Leaf Blight of Rice in Bangladesh

Dr. Ismail Hossain Mian
Professor
Department of Genetics and Plant Breeding, BSMRAU, Gazipur.

Dr. Md. Abu Ashraf Khan
Professor
Department of Genetics and Plant Breeding, BSMRAU, Gazipur.

Dr. M. A. Khaleque Mian
Professor
Department of Genetics and Plant Breeding, BSMRAU, Gazipur.

Abstract/ Executive Summary:

Pathotypes or race of bacterial plant pathogens is generally grouped on the basis of virulence phenotypes on a set of differential varieties of rice. In the present investigation, nine near-isogenic lines (NILs) of rice with distinct genes for bacterial leaf blight resistance were tested to find out virulence of nine isolates of AT oryzae pv. oryzae collected from different locations of Bangladesh. The symptoms developed by those isolates were clear to distinguish virulent and avirulent isolates. Based on susceptibility of the differentials and virulence of the isolates, in terms of lesion length, the isolates were grouped into 8 different pathotypes. Of them three isolates (ISO-8, ISO-9, BX09) showed identical virulence on the differentials and they were grouped as pathotype 8. Other 7 isolates (ISO-1 to ISO-7) were grouped into 7 different pathotypes (Pathotype 1 to pathotype 7). The most virulent pathotype was ISO-8 followed by ISO-3 and ISO 9. The least virulent pathotype was ISO-5 followed by ISO-1 and ISO-7. The maximum resistance frequency was showed by IRBB21 (Xa2) followed by IRBB5 (Xa5) and IRBB7 (Xa7). The minimum resistance frequency was found in IRBB13 (Xa13) followed by IRBB10 (Xa10), IRBB2 (Xa2) and IRBB11 (Xa11).

Keywords: Bacterial leaf blight of rice, Rice of Bangladesh, Rice

Location: Leaf samples of rice infected with bacterial leaf blight (BLB) were collected from farmers' fields from the districts of Gazipur, Tangail and Chittagong.

Start Date: 01-06-2009

End Date: 30-06-2010

Program Area: Pest Management

Commodity: Rice

Objectives:

In view of above facts the present investigation was conducted to survey races of X. oryzae pv. oryzae in some selected areas of Bangladesh.

Methodology:

Leaf samples of rice infected with bacterial leaf blight (BLB) were collected from farmers' fields in the districts of Gazipur, Tangail and Chittagong during boro season of 2010. Nine isolates of associated bacterium were isolated from the samples using peptone sucrose agar (PSA) medium. The isolates were purified following single colony selection technique and identified as X. oryzae pv. oryzae. To determine pathogenic variation of the isolates, their pathogenicity was performed on a set of nine near-isogenic lines (NILs) obtained from BRRI. One susceptible rice variety 'Purbachi' and an advanced line of rice, IRBB65, and one standard isolate of X. oryzae pv. oryzae (BX09) were included in the test for comparison. The experiment was conducted during Boro season of 2009. Thirty days old single seedling was transplanted in the field maintaining row to row and hill to hill distance of 20 cm. Ten sets of nine NILs were planted for ten isolates maintaining 40 cm distance from each set. At the maximum tillering stage of rice plants, 8-10 leaves/hill were clipped with a sterile scissor dipped in the inoculum suspension of the bacterial isolates (108 CFU/ml). Three hills of each of the NILs were inoculated with each isolate. For data collection, a total of 20 inoculated leaves were selected for each isolate and data on lesion length developed on leaves was measured. Disease reactions of the NILs to the isolates were categorized based on lesion length, where <3 cm was considered as resistant (R) and >3 cm was rated susceptible (S). The X. oryzae pv. oryzae isolates which produced more than 3 cm length of lesion on inoculated leaves were considered as virulent and the NILs were considered as susceptible, and those produced less than 3 cm lesion were noted as avirulent and the NILs were as susceptible.

Source of Information: BSMRAU. Summary Report of Research Review Workshop (2008-09).

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Similar results were also obtained by other investigators who worked in other countries with other isolates of the pathogen (Ikeda et al., 1990, Mazzola et al., 1994, Noda et al., 2001, Khan et al., 2009). Khan et al., (2009) tested 41 Bangladeshi isolates of X. oryzae pv. oryzae using the same set of differentials and grouped the isolated into 6 pathotypes. Pathotypes 1 contained 33 isolates, 2 contained 3 isolates and pathotype 3 contained 2 isolates. Each of pathotypes 4, 5 and 6 contained only one isolate. In the present investigation, the BLB resistance gene showed 9.09 to 63.64% resistant reaction to the isolates tested. Among 8 pathotypes identified, ISO-8, ISO-9 and BX09 were most virulent. Among the differentials IRBB13 (Xa13) and IRBB 10 (Xa10) genes were found susceptible to almost all the tested isolates.

Knowledge Management: Report/Proceedings