The document summarizes information about wheat blast, a disease of wheat caused by the fungus Pyricularia oryzae. It provides background on the disease's emergence and spread, symptoms, effects on wheat quality, and discusses disease management strategies and host resistance. Recent outbreaks in Bangladesh in 2016 demonstrated the pathogen's ability to spread to new regions outside of South America, representing a serious new threat to global wheat production.

1. COURSE SEMINAR ON
Wheat Blast : Fancied threat in India
SUPERVISOR
DR. D. D. Bhutia
ASST. PROFESSOR
DEPARTMENT OF MYCOLOGY AND PLANT PATHOLOGY
INSTIUTE OF AGRICULTURAL SCIENCES
BANARAS HINDU UNIVERSITY
PRESENTED BY
RAVI JHA
ID.NO : M-15153

2. Wheat
- Highest productivity (FAOSTAT, 2014)
- South Asia is home to 300 millions undernourished people and
inhabitants consume over 100 millions tonnes of wheat each year...
(CIMMYT, 2016)
- Attachment with crop since civilization.
- leading crop after Rice.
- Wheat provides 17% of calories in the human diet.

3. Food security challenge
• 2 billion people is going to be added in coming 30 years.
• Food production need to be increased by 70% over next 25 years.
• >250,000 plant species described/predicted.
• >30,000 plant species are edible.
• ~7,000 species used for food.
• 120, plants species are currently cultivated.
• Just 11 plant species provides 93% of the calories we human consumed.
• Same 11 plant species that human have been eating for 10,000 yrs.
Source: FAO, http: // www.fao.org/docrep/x0262e/x0262e02.htm

4. What?? Why??

5. -
Pyricularia oryzae is a species complex (Couch & Kuhn 2002).
-Cause blast in more than 50 species of poaceous plants. E.g.:
Oryza pathotype, pathogenic on rice
Setaria pathotype, pathogenic on foxtail millet
Eleusine pathotype, pathogenic on finger millet and
Triticum pathotype, pathogenic on wheat (Urashima et al ., 1998)
- First reported in Parana State, Brazil in 1985 (Igarashi et al., 1986)
-Lack of resistant cultivars and effective fungicides cause crop
losses from 40–100 % (Silva et al ., 2009) .
-Wheat blast is considered as a major quarantine disease in S.A.

6. - Wheat blast has been increasing in
importance and area impacted since
1985, with recent epidemics in 2009
and 2012 in Brazil, 2014 in Bolivia and
2016 in Bangladesh.
- The threat to United state is under
evaluation.
- Wheat blast symptoms resembles
with Fusarium head blight and Boron
deficiency.
- “One of the most fearsome and
intractable wheat disease in recent
decades”. CIMMYT, 2016
Pc : Kansas state
university

7. Causal organism
• Initially thought to be P. Oryzae and
some author named as Triticum isolates
of P. oryzae. Sprague (1950)
• Later Kohli et al. preferred name as
Pyricularia grisea.
• Using multilocus phylogenetic analysis
Couch and Kuhn(2002) described P. oryzae
distinct from P. grisea.
• Recently Castroagudin et al. (2016) conducted phylogenetic assays
on different isolates of P. oryzae from sympatric populations of grasse
s growing in or near wheat fields, so based on clades they conclude P.
oryzae pathotype Triticum to be the pathogen responsible for
wheat blast.
Fig. Two septate pyriform conidia of Pyricularia
on wheat Urashima et al ., 2010

8. Global spread of disease
• Further spread to Bolivia, Argentina, Paraguay and Uruguay and
infected 3 millions hectares of land causing severe crop losses
(Kohli et al., 2011).
• Observed in Kentucky in 2011, vigorous surveillance helped stop
spread in U.S.A (Callaway, 2016).
• The disease has never been reported outside South America till
2016. (Maciel 2011)
Pc : CIMMYT
B.
Ur.Ar.
Pa.
Bo.

9. Recent spread in Bangladesh
• On Feb, 2016 outbreak was reported in Bangladesh. (Callaway,
2016; Malaker et al., 2016)
• Affected in 15000 hectares with resultant fall in production by
20%. (Malaker et al., 2016)
• Extant 15% wheat area been observed under disease.
Islam et al .,
2016

10. 0
10
20
30
40
50
60
70
80
M C JE JH BH K BA P
% INFECTED FIELD
AVG. YIELD LOSS
The severity of wheat blast and associated yield losses varied among districts.
Islam et al ., 2016

13. Symptomatology
• Wheat blast infects all above
ground parts of plant.
•On leaves lesions vary in shape
and size depending on the stage
of plants.
• As plants grow older, lesions are
less frequent.
• Lesions with white centre and
of reddish brown margin on
upper side, dark grey on the
underside of the leaf can be
observed on both young and old
infected leaves.
Contd.. Pc : Kansas state university

14. -Major symptom on head/spike
infection.
- Occurs on the glumes, awns and
rachis.
- Blackening of the rachis, lower
nodes, shriveling of grains, low test
weight has also been observed
(Malaker et al., 2016) .
- Infected glumes support elliptical
lesions with reddish brown to dark
grey margins and white to light
brown centre.
- The pathogen produce non host
specific toxin pyricularin . (Agrios,
2005)
- Infecting place on head determine
partial or full head drying. Pc : CIMMYT

15. Different strains are isolated from infected sample
of wheat
Similar symptoms as in wheat No symptoms
Barley Eleusine indica Rice
Islam et al ., 2016

16. Disease Cycle and Spread
- Wheat blast exhibits almost same disease
cycle as rice blast.
- Pyriform conidia considered to be
characteristics features for disease
developments.
- Conidium has three cells, with each having
single nucleus per cell where isolates can be
purified with single conidium.
- (+)nce of melanin in appresoria build up very
high pressure to puncture host surface.

17. • In addition, crosses of wheat-derived isolates with strains
from Eleusine coracana, Urochloa plantaginea, and Setaria
indica (Paniceae) produced mature perithecia with viable
ascospores (evidence of fertile crosses) (Urashima et al.,
1993).
• Young and expanding leaves are more susceptible to fungus.
• Seed is the primary sources of inoculum to new areas (Greer
and Webster, 2001).
• grass strain jumping to wheat can also cause wheat blast
(Callaway, 2016).
• After entry into host, the fungus colonizes for 4 days without
any visible appearance.

18. -The production losses by Pyricularia blast
varies from very low to 100% (Goulart and
Paiva, 1990; Goulart
et al.1992).
-Highest loss occurs when fungal infection
occurs at the base of the rachis restricting
the development of grains and killing of
spike (Kohli et al., 2011).
-First epidemic in Paraguay caused more
than 70% losses and in low lands of Santa
Cruz region of Bolivia in 1996 resulted in
80% yield reduction in
wheat.

19. • According to Kohli et al., (2011), most severe blast years coincide
with wet years i.e continuous rains and average temperatures
between 18-20°C during the flowering stage of the crop followed
by sunny host and humid days.
• Under controlled conditions highest blast intensity at 30°C was
observed with increased duration of wetting period and lowest
at 25°C with a wetting period of less than 10h.
• However, with increasing wetting period of 40h at 25°C blast
intensity of 85% was observed.
• Sprinkler irrigation may expose the plants to blast.
• Global temperature rise and EI nino may predispose wheat to
blast.

20. Fig. 4 Transcriptome sequencing of infected leaves from farmer fields reveals Magnaporthe oryzae transcripts in symptomatic samples. a Comparison
of sequence read mapping data from the four sample pairs to the genomes of wheat blast fungus M. oryzae BR32 (in blue) and wheat (light gray). b, c
Scatter plots of fragments per kilobase of transcript per million (FPKM) values from sample pair 7-F7 (b) and 12-F12 (c) aligned to the combined
transcriptomes of wheat and M. oryzae BR32. Transcripts from wheat (100,344) are shown in light gray and transcripts from M. oryzae BR32 (14,349)
are shown in blue.
Transcriptome sequencing
Islam et al ., 2016

21. Fig. 5 The origin of the Bangladesh wheat blast fungus. a Maximum likelihood genealogy inferred from the concatenation of aligned genomic
data at 2193 orthologous groups of predicted transcript sequences. Scale bar represents the mean number of nucleotide substitutions per site.
b Population genomic analyses of transcriptomic single nucleotide polymorphisms among M. oryzae isolates from wheat in Brazil and
Bangladesh. The network was constructed using the Neighbor-Net algorithm. The scale shows the number of informative sites
Population and Phylogenomics approaches
Islam et al ., 2016

22. Effects of wheat blast on WTQ
Wheat sample characterization WTQ parameters
Blast Incidence
Disease severity
Grain Yield
Hectoliter weight (HW)
Grain Diameter (GDIAM)
Flour color (a*- red color)
Grain hardness index (GHI)
Alveography (L, extensibility)
Alveography ( G, swelling
index)
Solvent retention capacity
Grain falling number (GFN)
Thousand kernel weight (TKW)
Miranda et al ., 2016

23. WTQ Correlation with disease
Blast incidence - (ve)
correlation
-Grain Yield
- Hectoliter weight
- TKW
Disease severity
+ (ve)
correlation
-TKW
-Grain Diameter
- a*
Grain Yield
+ (ve)
correlation
-Hectoliter weight
-TKW
-Grain Diameter
- SRC
-L, extensibility
-G, swelling index
Miranda et al ., 2016

25. • Wheat isolates produced perithecia in more than 93% of cases
and 68% formation was sexual organ, while for Rice isolates
24% formed perithecia and none was reported producing
sexual organs completely. (Urashima et al. 1993)
• The optimum temperature for the development of wheat M.
Oryzae was developed by an equation and was found to be 26-
28 degree celcius. (Cardoso et al. 2008)
• Relationship of wheat blast with global warming.
• A view that wheat blast could not become a serious problem in
European countries, as well as Canada and the USA due to its
humidity and temperature.

26. • Quarantine
• Crop rotation
• Fungicide application inhibits melanin production in
appresoria .
• Genetic resistance – Lr34 gene (Krattinger et al ., 2015)
• Destruction of auxiliary hosts
• Avoidance of sprinkler irrigation and infected area.
• Brazilian wheat cultivars BR18, IPR85, CD113 have shown
moderate level of host resistance.
• Derivative accessions of CIMMYT line Milan have also been
shown to possess a high level of resistance (Kohli et al., 2011).
• Application of silicon containing basic ground granulated blast
furnace slag has been found to reduce blast (Agrios, 2005).

28. • Kohli MM, Mehta YR, Guzman E, De Viedma L, Cubilla LE. Pyricularia
blast —a threat to wheat cultivation. Czech Journal of Genetics and Plant
Breeding. 2011;47:S130–4.
• Goulart ACP, Sousa PG, Urashima AS. Damages in wheat caused by
infection of Pyricularia grisea. Summa Phytopathologica 2007;33:358–
63. doi:10. 1590/S010054052007000400007.
• Igarashi S, Utiamada CM, Igarashi LC, Kazuma AH, Lopes RS.
Pyriculariaemtrigo. 1. Ocorrência de Pyricularia sp. no estado do Paraná.
Fitopatol Bras. 1986;11:351–2.
• Ou SH. Rice diseases. Kew, UK: Commonwealth Mycological Institute,
CAB; 1985.
• Cruz CD, Peterson GL, Bockus WW, Kankanala P, Dubcovsky J, Jordan KW,
Akhunov E, Chumley F, Baldelomar FD, Valent B. The 2N translocation
from Aegilops ventricosa confers resistance to the Triticum pathotype of
Magnaporthe oryzae. Crop Sci. 2016;56:1–11
doi:10.2135/cropsci2015.07.0410.

29. • Castroagudin VL, Ceresini PC, Oliveira SC, et al. Resistance to QoI
fungicides is widespread in Brazilian populations of the wheat blast
pathogen Magnaporthe oryzae. Phytopathology. 2015;104:284–94.
• Callaway E, Devastating wheat fungus appears in Asia for first time.
Nature 2016; 532:421-2. doi:10.1038/532421a.
• Urashima AS, Igarashi S, Kato H. Host range, mating type and fertility of
Pyricularia grisea from wheat in Brazil. Plant Disease. 1993;77:1211–6.
• Urashima AS, Martins D, Bueno CRNC, Favaro DB, Arruda MA, Mehta YR.
Triticale and barley: new hosts of Magnaporthe grisea in São Paulo,
Brazil — relationship with blast of rice and wheat. In: Kawasaki S, editor.
Rice blast. Berlin: Springer; 2004. p. 251–60.
• Duveiller E, Hodson D, Tiedemann AV. Wheat blast caused by
Maganaporthe grisea: a reality and new challenge for wheat research.
In: Dzyubenko NI, editor. Abstracts of the 8th International Wheat
Conference, 1–10 June 2010, St. Petersburg, Russia; 2010. p. 247–8.
• CIMMYT (2016). Wheat Blast. Retrieved from
http://www.cimmyt.org/wheat-blast/