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Virulence Analysis of Pyricularia Grisea Population Causing Rice Blast Disease in Bangladesh Using Differential Varieties (monogenic Lines)

Dr. Md. Ansar Ali
Chief Scientific Officer
Plant Pathology Division,Bangladesh Rice Research Institute, Gazipur-1701, Bangladesh

Dr. Mohammad Ashik Iqbal Khan
Senior Scientific Officer
Plant Pathology Division, Bangladesh Rice Research Institute,Gazipur-1701, Bangladesh

Mohammad Hossain
Senior Scientific Officer
Plant Pathology Division, Bangladesh Rice Research Institute,Gazipur-1701, Bangladesh

Zakia Rahman Moni
Scientific Officer (Project)
Plant Pathology Division, Bangladesh Rice Research Institute, Gazipur-1701, Bangladesh

Abstract/ Executive Summary:

It was recognized that virulent frequencies of the blast pathogen varies from the lowest 1.7 with IRBL9-W to 93.3 with IRBL19-A. More than 80% virulent frequencies were recognized with IRBL20-IR24 (91.7%), IRBLzt-T (85%), IRBLt-k59 (83.3%) and IRBLks-S (81.7%) while the least virulent frequencies were associated with IRBL9-W (1.7%). Out of 60 isolates 52 races were recognized. Of them, duplicated races for U61-i0-k000-z04-ta403, U63-i0-k000-z06-ta203, U63-i0-k000-z06-ta403, U63-i0-k100-z04-ta403, and U63-i0-k135-z04-ta403 were recorded while U61-i0-k000-z05-ta403 and U63-i0-k100-z04-ta421 were in triplicate. Blast isolates were categorized into 8 U blast pathotypes, 7 for i blast pathotypes, 11 for k blast pathotypes, 7 for z and 18 for ta blast pathotypes. Of them predominant blast pathotypes were U63, i0, k000, z04 and ta403. It was noted that isolates from eastern region were more diverse than other region. Genes pi9, pita-2, pish may be used for breeding blast resistant variety in Bangladesh.

Keywords: Virulence analysis, Pyricularia grisea, Rice blast, Differential varieties

Location: Plant Pathology Division, BRRI HQ

Start Date: 01-07-2010

End Date: 30-06-2011

Program Area: Pest Management

Commodity: Diseases

Objectives:

To develop a novel differential set for race identification in Bangladesh

Methodology:

A total of sixty blast isolates (single spore culture) collected from different AEZs of Bangladesh were used in this study. Among the isolates, 5, 8, 2, 9, 28 and 8 were collected from AEZ-3, AEZ-7, AEZ-9, AEZ-13, AEZ-19 and AEZ-28 respectively. Seasonal and regional collections are illustrated. Thirty monogenic lines having individual blast resistance gene (targeting 23 resistant genes) obtained from IRRI. Two varieties LTH and US-2 were included as susceptible check. Monogenic lines (ML) and susceptible checks (SC) were seeded in two individual plastic trays (having 35 holes of seeding options, 34 used) for each isolate. Seeds of individual ML and SC were soaked overnight in Benlate solution and upon washing in water the seeds were further left for 24 hr for sprouting. Four to 6 sprouted seeds were sown for each monogenic line. Plants were inoculated 21 days after seeding. Inoculums revived from paper disk (stock) were transferred on the same day of seeding onto oat meal agar plate (20 mm depth) following NIAS method cited by N. Hayashi et al. (2009) and incubated for 14 days at 25⁰C. Duplicate plates were prepared for each isolates. After 14 days of incubation surface of the fungal growth were scrapped with a tooth brush. The scrapped plates opened in the plastic tray with wrapping film pitted several holes for aeration and left 7 days under light for sporulation. Conidia were harvested by paintbrush upon pouring 10-15 ml chilled distilled water with 0.01% Tween 20 for each plate and filtrated through 4 layers of cheese cloth. Spore concentration was adjusted to 1 x 105/ml and 30 ml conidial suspension was prepared for each isolate. Twenty one days old seedlings was sprayed with the spore suspension and for each isolates two trays were used. Sprayer was rinsed with ethanol after each isolate spray. The inoculated plants were incubated for approximately 24 hr at 25⁰C in a dew chamber and transferred to green house in plastic tray having water at the base line of seedlings at the same temperature. Disease reaction for each line was scored in 0-5 scale of N. Hayashi et al. (2009) seven days after inoculation. Scale: 0-2 scored as resistant (R) and 3-5 as susceptible (S).Blast isolates were classified into races following the new designation system of Hayashi and Fukuta (2009). Cluster analysis and Pathotypes will also be clarified.

Source of Information: Proceedings of BRRI Annual Internal Review for 2010-11

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Blast isolates were categorized into 8 U blast pathotypes, 7 for i blast pathotypes, 11 for k blast pathotypes, 7 for z and 18 for ta blast pathotypes. Of them predominant blast pathotypes were U63, i0, k000, z04 and ta403. It was noted that isolates from eastern region were more diverse than other region. Genes pi9, pita-2, pish may be used for breeding blast resistant variety in Bangladesh.

Knowledge Management: Report/Proceedings