In Bangladesh, rice blast has been re-emerged as the most devastating disease of rice (Khan et al. 2014; Hossain et al. 2017). Recently, the most popular and mega rice varieties of rice developed by the BRRI such as BRRIdhan28 and BRRIdhan29 showed high susceptibility to blast (Annonymous 2011; Hossain et al. 2017). Yield losses due the blast was estimated up to 70%. Hossain and co-workers (2017) recently showed that yield losses caused by blast in hybrid variety Jhalak, BRRIdhan47, BRRIdhan29 and BRRIdhan28 were 69, 60, 40 and 20%, respectively. Rice cultivation in Bangladesh is year-round. Highest blast incidence is occurred in Boro (November-June) and Aman (July-December) seasons. A wide variation in virulence was found in 267 identified races of rice blast fungus in Bangladesh (Khan et al. 2016). Just after one year of first wheat blast epidemic in South and South-Western Bangladesh, a severe outbreak of rice blast in the same districts and some other districts of Bangladesh poses a serious threat to the future food security of the country.
To rapidly determine the precise genetic identity and diversity in the rice blast fungus, we applied field pathogenomics, in which we performed transcriptome sequencing of symptomatic and asymptomatic leaf samples directly collected from infected rice fields of Bangladesh in 2017.
we collected samples from the several affected districts in Khulna division. Typical blast symptoms were observed in leaves, nodes, necks and spikes of rice plants.
Blast symptoms observed in the fields
Sequence data from the symptomatic leaf samples are shown in the table below.
RNA-Seq data from symptomatic leaf samples
| Sample Name | Date Collected | Location | Rice Variety | Crop growth stage | Severity of attack (% leaf area infection) | Raw Reads |
|---|---|---|---|---|---|---|
| RB-2-CH_S1 | April 16, 2017 | Sarojganj, Chuadanga | BRRI Dhan-28 | Field sample | N.D. | Reads_1 Reads_2 |
| RB-3-CH_S2 | April 16, 2017 | Belgachi- Chuadanga | BRRI Dhan-28 | Field sample | N.D. | Reads_1, Reads_2 |
| RB-4-CH_S3 | April 16, 2017 | Damurhuda- Chuadanga | BRRI Dhan-28 | Field sample | N.D. | Reads_1, Reads_2 |
| RB-6-CH_S4 | April 16, 2017 | Darsana, Chuadanga | BRRI Dhan-28 | Field sample | N.D. | Reads_1, Reads_2 |
| RB-7-JI_S5 | April 17, 2017 | Kaligonj-Jhenaidah | BRRI Dhan-50 (bashmoti) | Field sample | N.D. | Reads_1, Reads_2 |
| RB-9-JO_S6 | April 17, 2017 | Ovoynogor-Jessore | BRRI Dhan-28 | Field sample | N.D. | Reads_1, Reads_2 |
| RB-11-JO_S7 | April 17, 2017 | Noyapara- Ovoynogor-Jessore | BRRI Dhan-28 | Field sample | N.D. | Reads_1, Reads_2 |
| RB-12-KH_S8 | April 17, 2017 | Fultola -Khulna | BRRI Dhan-64 | Field sample | N.D. | Reads_1, Reads_2 |
| RB-13-KH_S9 | April 17, 2017 | Fultola -Khulna | BRRI Dhan-50 | Field sample | N.D. | Reads_1, Reads_2 |
| RB-14-KH_S10 | April 17, 2017 | Fultola -Khulna | BRRI Dhan-28 | Field sample | N.D. | Reads_1, Reads_2 |
| RB-16-KU_S11 | April 17, 2017 | Kustia | BRRI Dhan-63 | Field sample | N.D. | Reads_1, Reads_2 |
| RB-17-AL_S12 | April 17, 2017 | Alamdanga, Chuadanga | BRRI Dhan-28 | Field sample | N.D. | Reads_1, Reads_2 |
Referrences
Anonymous (2011). Annual research review report for 2010-2011. Bangladesh Rice Research Insitute, Gazipur 1701, Bangladesh. Bangladesh Rice Research Institute.
Hossain M., Ali M. A. and Hossain M. D. (2017). Occurrence of Blast Disease in Rice in Bangladesh. American Journal of Agricultural Science 2017; 4(4): 74-80 http://www.aascit.org/journal/ajas
Khan M. A. I., Ali M. A., Monsur M. A., Kawasaki-Tanaka A., Hayashi N., Yanagihara S., Obara M., Mia M. A. T., Latif M. A. and Fukuta Y. (2016). Diversity and distribution of rice blast (Pyricularia oryzaeCavara) races in Bangladesh. Plant Dis. 100: 2025–2033.