This seminar explains about the yellow rust disease of wheat: Its genetics and prevention methods as well as molecular techniques to combat yellow rust

1. Yellow Rust In Wheat: Genetics And
Management
Presented by : Priyanka
Ph.D. II year
(A-2019-40-018)
CSK HPKV, Palampur
Credit Seminar

2. INTRODUCTION
A major staple food at global level and occupies about 21.8 %
of total cultivated area
Factors affecting
destabilization of wheat
yields
BIOTIC FACTORS
ABIOTIC FACTORS
Affected by a number of pathogens causing disease out of
which the rust pathogens are very important.

3. Rust Pathogen Nomenclature
Puccinia recondita f. sp.
tritici
The pathogen of leaf
rust; also known as
brown rust
Puccinia striiformis f. sp.
tritici
The pathogen of stripe
rust; also known as yellow
rust.
Puccinia recondita f. sp.
tritici
The pathogen of leaf
rust, also known as
brown rust

4. Dr. K.C. Mehta’s Classical Work
Yellow rust
Source: North west
Himalayas
Target: North India
NILGIRIS
Black rust
Source: Nilgiris
Target: Peninsular India
Brown rust
Source: Nilgiris and
Nepal
Target: Entire wheat
area

5. Dissemination of the three rusts from foci
of infection
Joshi et al. 1985

6. WHAT IS YELLOW RUST
CAUSAL ORGANISM Puccinia striiformis f. sp. tritici
Globally significant disease
Disease of cooler climate (2°C - 15°C)
Crop damages can reach 50 – 100%

7. SYSTEMATIC POSITION
Kingdom: Fungi
Phylum: Basidiomycota
Class: Urediniomycetes
Subclass: Incertaesedis
Order: Uredinales
Family: Pucciniaceae
Genus: Puccinia
Species: P. striiformis f.sp.tritici

8. HISTORY
Gadd (1777) Yellow Rust mentioned for the first time
Schimdt (1827) Described the pathogen infecting barley glumes as
Uredoglumarum
Westend (1854) Named the pathogen as Puccinia striiaeformis (with
reference from rye).
Fuckel (1860) Named it as Puccinia staminis
Eriksson &
Henning (1894)
Yellow rust as Puccinia glumarum.
The term was reviewed again in 1953 and was changed to specials of Puccinia
striiformis

9. Pathogen Characters
Yellow Rust is considered to be an obligate parasite.
The fungus produces bright yellow to orange uredospores 20 to 30 µm in
diameter. These spores have thick and echinulated walls and are contained
in sori or pustules on the plant .
Uredospore production usually is followed by teliospore production late in
the growing season.
Earlier, no alternate hosts were known. But now it has been found that alternate
hosts are barberry (Berberis chinensis, B. koreana, B. holstii, B. vulgaris, B.
shensiana, B. potaninii, B. dolichobotrys etc.)

10. Symptoms And Spore Morphology

11. LIFE CYCLE

12. Rust Score Guidelines
HOST RESPONSE AND INFECTION TYPE DESCRIPTIONS USED IN THE WHEAT STRIPE
RUST SYSTEM

13. Rust Score Guidelines
MODIFIED COBB’S SCALE
The modified Cobb scale: (A) Actual percentage occupied by rust uredinia; (B)
Rust severities of the modified Cobb scale (Peterson et al., 1948)

14. Predominant Pathotypes of Wheat Rusts
in India
Area Black Brown Yellow
Nilgiri hills 40A 77-9,77-5 I
Peninsular India 11 104-2,77-9 –
Central India 40A 104-2,77-9,77-5 –
Eastern India 21A-2 77-5 –
Northern India 21-1, 21A-2 77-5,104-2
46S119,110S119,46S
117,238S119
Regional Station, Shimla-ICAR, IIWBR

15. GENETICS OF RUST RESISTANCE IN WHEAT
• Biffen (1905) first demonstrated that resistance to stripe rust in
wheat follows Mendel’s laws, the genetics of resistance to stripe
rust has been studied for a century.
• Studies conducted worldwide on the genetics of rust resistance
in wheat
• Many insights gained into the structure and functional aspects
of the genetic architecture of rust resistance in wheat
• A total of 60 Sr, 79 Lr and 82 Yr genes designated
• Many temporarily designated and undesignated resistance genes
and QTLs have been indicated in many studies

16. TYPES OF RESISTANCE
Sr.NO WAYS OF SEPERATION RESISTANT TYPE (I) RESISTANT TYPE (II)
1. Growth Stage All-stage resistance (ASR) Adult Plant Resistance (APR)
2. Specificity Vertical Resistance Horizontal Resistance
3. Degree Of Resistance Complete Resistance Incomplete Resistance
4. Speed Of Symptoms
Development
Fast Rusting (super
susceptible/no resistance)
Slow rusting
5. Response to Temperature Temperatures non sensitive Temperature sensitive
6. Inheritance Qualitative resistance Quantitative resistance
7. Effect of genes Major gene resistance Minor gene resistance
8. Number of genes Monogenic resistance Polygenic resistance
9. Molecular basis NBS-LRR type resistance Non NBS-LRR type
10. Durability Non durable Durable
11. Race-specificity, growth
stage and temperature
sensitivity
Race-specific all-stage
resistance
Non-race specific high-
temperature adult-plant
(HTAP) resistance

17. DURABLE RESISTANCE
Resistance which has remained effective in a cultivar during
its widespread cultivation for a long sequence of
generations or period of time in an environment favorable
to a disease or pest (Johnson 1988).
A combination of several genes may confer durability of
resistance on the premise that components such as
increased latent period, smaller pustule size, reduced
number of uredia per unit area etc. may contribute towards
slow development of rust

18. Linkage Between Rust Resistance Genes
A number of rust resistance genes show linkage, which offers an
added advantage towards multiple rust resistance breeding in
wheat.
The linked genes for rust resistance in wheat:
Sr2/Lr27/Yr30 Sr15/Lr20 Sr23/Lr16
Sr24/Lr24/Yr71 Sr25/Lr19 Sr31/Lr26/Yr9
Sr38/Lr37/Yr17 Sr39/Lr35 Lr57/Yr40
Lr62/Yr42 Lr76/Yr70 Lr25/Lr18
Yr51/Yr60
Tomar et al. 2014

20. SLOW RUST RESISTANCE
A type of resistance where disease progresses at
retarded rate, resulting in intermediate to low disease
levels against all races of pathogen (Caldwell 1968).
The purpose of slow rusting or partial resistant is to
achieve durable resistant and provide a sustainable
approach of disease control
Numbers of slow rusting gene have been identified so far.
However, the known slow rusting genes which present in
number of CIMMYT release germplasm line or cultivars
are Lr34 and Lr46 present in combination with other minor
gene (Bai et al., 1999).

21. Expression Of Resistance
Gene interactions:
• Epistasis is generally observes when 2 or more resistant genes are
present together i.e. the gene conditioning the lowest infection type or
highest level of resistance is expressed
• Additive effects:
 Additive interactions for resistance to leaf and stripe rust among Lr46,
Yr29 and 3-4 QTL’s in RIL’s derived from Avocet × Kundan
 Yr 81 interacted with Yr 18 towards enhanced stripe rust resistance
 Yr 82 interacted with Yr 29 to produce lower adult plant response to
stripe rust

22. Expression Of Resistance
• Complementary effects
The Yr17 resistance in Avocet R conditioned by two
complementary genes, Yr 73 on 3DL and Yr 74 on 5BL
• Suppressor effects
A Yr 18 suppressor was reported in four Chinese Landraces

23. Pleiotropic effect of Resistant genes
• Changes in two critical amino acids in the resistant allele of Yr46/Lr67
result in encoding a protein that has lost hexose transport function and
could therefore disturb the balance of sugars between the extracellular
and intracellular spaces of the leaf. This may reduce the availability of
nutrients inside the host cell, hence the effectiveness of this gene
against multiple biotrophic fungi. Alternatively, altering apoplastic
sugar concentration may induce activities of defense responses
• The gene Lr34/Yr18 has been shown to encode an ATP binding
Cassette (ABC) transporter. However, the basis of resistance and the
substances of this ABC transporter are yet unknown.

24. PAPR Genes
• Lr 34/ Yr 18/ Sr57/Pm38/Sb1/Bdv1/Ltn1 (7DS)
• Lr 46/ Yr 29/ Sr 58/Pm 39/ Ltn 2 (1BL)
• Lr 67/ Yr 46/ Sr 55/ Pm 46/ Ltn 3 (4 DL)

25. Effectiveness of PAPR Genes
• Although PAPR genes are widely effective, the
level of resistance imparted by them on their
own under heavy disease pressure is not
adequate and need to be complemented by
other resistance genes
• Their expression is significantly influenced by
the environmental conditions.

26. MECHANISM OF RUST RESISTANCE
Periyannan et al. 2017

28. Cataloged genes conferring resistance to Puccinia
striiformis f.sp.tritici in wheat

29. Cataloged genes conferring resistance to Puccinia
striiformis f.sp.tritici in wheat
Park et al. 2016

30. RESISTANCE GENES TRANSFERRED FROM OTHER
TRITICUM spp. AND WILD RELATIVES
Source Rust resistance genes
T. dicoccoides Lr 33, Lr 64, Yr 13, Yr 35, Yr 36
T. spelta Lr 44, Lr 65, Lr 71, Yr 5
T. Turgidum ssp. dicoccum Sr2, Sr9d, Sr9e, Lr 14a, Yr 15
T. Turgidum ssp. durum Yr 7, Yr 24, Yr 53, Yr 56
Aegilops caudata Sr 34, Yr 8
Aegilops geniculata Sr 53, Lr 57, Yr 40
Aegilops kotschyi Lr 54, Yr 37
Aegilops neglecta Lr 62, Yr 42
Aegilops squarossa Lr 40, Lr 41, Lr 42, Sr 33, Sr 43,Yr 28
Aegilops umbellulata Lr 9, Lr 76, Yr 70
Aegilops ventricosa Lr 37, Yr 17
Thinopyrum intermedium Sr 44, Yr 50

31. Effective ways to fight rusts in India
• Survey and surveillance in mediterranean
areas on our own or with international
collaboration
• Understanding of evolution of biotypes in
races
• Durable resistance genes combating threat of
new races

32. Methods of Controlling the Rust Diseases
Roelfs et al. 1992

33. Gene Pyramiding
Gene pyramiding defined as the method aimed
at assembling multiple desirable genes from
multiple parents into a single genotype. The end
product of a gene pyramiding program is a
genotype with all of the target genes.
Watson and Singh (1953) first introduced the concept called gene pyramiding

34. Different schemes of Backcrossing for Gene
Pyramiding
Stepwise gene transfer
Simultaneous gene
transfer
Stepwise and
simultaneous gene
transfer
Joshi and Nayak 2010

35. GENETIC STOCKS WITH PYRAMIDED RUST RESISTANCE
Bhardwaj et al. 2019

36. GENE DEPLOYMENT
The development and deployment of resistant wheat varieties has proven to be the
most economic, effective and efficient means of managing rust diseases.
Gene deployment is a promising and effective strategy to curtail the rust epidemics.
Stripe rust resistance gene Yr9 provided resistance for a very long period in India but
now has become ineffective due to evolution of new virulences.
Deployment of genes such as Yr2, Yr 18 , Yr 29 and Yr46, which are individually as
well as collectively effective against the prevailing races would be an appropriate
strategy to check the losses due to stripe rust.
A combination of all stage (seedling) resistance, slow rusting resistance, and APR of
both the race specific and non-race specific types is deployed for the Agronomy
2019, 9, 892 9 of 14 strategic management of wheat rusts
Tomar et al. 2014

37. Multilines
• Jensen(1952) gave the concept of mutilines
• Borlaug (1953) used an equivalent term ‘composite’ and
proposed as a new approach for resistance to stem rust
of wheat (Puccinia graminis tritici)
Sonalika Multilines
MLSKA-9 (6 isogeni lines)
MLSKA-12 (9 isogenic lines)
Sonalika Multiline-1 (6 components)
First commercial multiline
Miramar 63
Miramar 65
Kalyan Sona Multilines
KSML 3(6 components)
KML 7406 or Bithoor (9 components)
MLKS 11 (8 components)
Yaqui type multiline developed
but could not be release due to
availability of semi dwarf wheats
Tumult based on 7 resistance
sources against yellow rust
released in Netherlands

38. CHEMICAL CONTROL
If the yellow rust is noticed in the wheat crop, it is advised to spray the crop with
Propiconazole (Tilt) 25 EC @ 0.1 % (1 ml / litre) using power sprayer or tractor
mounted boom sprayers. 0.5 litre per hectare of the fungicide shall be sufficient to
effectively cover the wheat crop.
Source: Directorate of Wheat
Research, Karnal
Use of chemicals for rust control dates back to year 1900. Sulphur had been a widely
recommended chemical
Good control of wheat rusts can be achieved with commercially available fungicides
and proper application timing.
Post-infection application of nickel salts were found effective in rust control in 1958
and in 1963 commercial control of Puccinia striiformis with nickel fungicides was
reported

39. CASE STUDIES

40. • Materials and Methods :

41. • Results :
Randhawa et al. 2019

43. • Materials and Methods :
In this study, 70 publically available
molecular markers were used to identify
the distribution of 35 Yr genes in 68
wheat genotypes. Out of 35 Yr genes, 25
genes amplified the loci associated with
Yr genes. Of the
35, 18 were all-stage resistance ASR (All-
stage resistance) genes and 7 (Yr16,
Yr18, Yr29, Yr30, Yr36, Yr46 & Yr59)
were APR (Adult-plant resistance) genes
.
• Results :
At the adult-plant stage, disease data on
infection types and severity was recorded.
Fifty-three genotypes were found resistant
(accounting for 77.94% of total genotypes,
3 genotypes (4.4%) showed trace
resistance, 7 genotypes (10.3%) were
moderately susceptible (ITs 3) and 5
genotypes (7.35%) including infector (WH
711 and PBW 343) were susceptible.
Overall 60 genotypes expressed yellow rust
resistance under field conditions against
predominant yellow rust pathotypes i.e.
46S119, 110S119, 110S84
&78S84.
Marker assisted detection of 35 Yr genes
in wheat genotypes was carried out using
70 Yr gene linked markers. The results
indicated the effectiveness of these
markers for specific Yr gene which also
identified the resistant lines containing
multiple Yr genes.
Rani et al. 2019

44. Contribution of All stage resistant genes (ASR) and Adult Plant Resistant genes (APR) in
wheat genotypes
Rani et al. 2019

45. CONCLUSION
The ever changing nature of wheat leaf, stripe and stem rusts poses a serious threat to
future wheat production.
As an emergent tool for managing wheat rusts in India, fungicides belonging to
triazole (Propiconazole, Tebuconazole, Triadimefon), are kept ready for effectively
controlling wheat rusts at the rate of 0.1 percent.
However, resistant cultivars have remained popular among the farmers as they are
cost effective and environmentally neutral in terms of impact.
The emergence of new races of rusts require continued efforts to deploy new
resistance genes.

46. CONCLUSION
This collective effort in developing resistant cultivars and understanding disease
epidemiology has gradually reduced the magnitude and frequency of epidemics.
The claim is well verified with the fact that India has had no wheat rust epidemic for
the last 47 years even when many countries in the world have had rust outbreaks.
Rapid advances in molecular marker technologies are revolutionizing the ways in
which resistance can be manipulated in breeding programmes.
A number of rust resistant genes are still effective in different regions of the world.
Such genes need to be utilized in wheat crop improvement in planned and judicious
manner