Wheat is a major staple food of world population and occupies about 21.8 % of total cultivated area accounting for 35.5 % of total food grain production at global level. Wheat is the second most important cereal of India. India is a major producer of wheat, accounting for about 13.2 percent of the world tonnage. India’s share in global exports during the year 2014-15 was 1.8 percent (Anonymous, 2016)

1. Major Advisor : Dr. R. P. Saharan Adm. No : 2013A35D
Course No : GP 692 Date :20/05/2016
Genetics of Yellow Rust Resistance In
Wheat

2. Introduction
 Wheat is a major staple food of world population and occupies about 21.8 %
of total cultivated area accounting for 35.5 % of total food grain production at
global level
 Wheat is the second most important cereal of India.
 India is a major producer of wheat, accounting for about 13.2 percent of the
world tonnage
 India’s share in global exports during the year 2014-15 was 1.8 percent (Anonymous,
2016)

3. CURRENT Status of wheat cultivation
INDIA
Area 30. 37 m ha
Production 90.78 m
tones
Productivity 29.89 q/ha
HARYANA
Area 2.54 m ha
Production 10.74 m
tones
Productivity 42.28 q/ha
Anonymous, 2015

4. Wheat growing zones
Sr
N
o
Zones Center App.
Area
Funded Centers
1. Northern
Hills Zone
(NHZ)
Hilly areas of Jammu & Kashmir (excluding
Jammu & Kathua districts), H.P.( excluding
Una &Paonta Valley), Uttarakhand
(excluding Tarai region) & Sikkim.
0.8
mha
Palampur, Bajoura & Dhaula
Kuan
2. North
Western
Plains Zone
(NWPZ)
States of Punjab, Haryana, West U.P.
(excluding Jhansi division), Rajasthan
(excluding Kota & Udaipur divisions),
Delhi, Tarai region of Uttarakhand, Una &
Paonta valley of H.P. & Jammu & Kathua
districts of Jammu & Kashmir.
11.1
mha
Chatha, Ludhiana, Hisar,
Durgapur, Modipuram &
Pantnagar
3. North
Eastern
Plains Zone
( NEPZ)
East Uttar Pradesh, Bihar, Jharkhand, West
Bengal, Orissa, Assam & Plains of north
eastern areas.
9.5 m
ha
Kanpur, Faizabad, Varanasi,
Sabour, Ranchi, Kalyani,
Coochbehar, Shillongani &
Mantripukhari
4. Central Zone
(CZ)
M.P., Gujarat, Chharisgarh, Kota & Udaipur
divisions of Rajasthan & Jhansi division of
west U.P.
5.2
mha
Kota, Udaipur, Vijaypur, Sagar,
Junagarh, Gwalior, Rewa,
Powarkhedas, Bilaspur
5. Peninsular
Zone (PZ)
Maharashtra, Karnataka, Plains of Tamil
Nadu and Andhra Pradesh
1.6
mha
Pune, Niphad, Mahableshwar
& Dharwad
6. Southern
Hills Zone
Nilgiri & Palni hills of Tamil Nadu 0.1
mha
-
Singh et al., 2011

5. Incidence of Wheat Rusts in India
 All the wheat rusts were observed in India during
2014-15. This year was marked by low incidence of
wheat rust in India.
 Yellow rust was restricted to northern India in some
pockets in endemic form.
 Yellow rust was reported almost one month late to
previous years and remained below threshold level
because of the joint efforts of ICAR, SAUs and state
department of agriculture.
 So far 793 samples of three rusts of wheat and yellow
rust of barley have been analyzed from India and
neighboring countries.
 ( Source: Progress report 2014-15, All India Coordinated Wheat and Barley Improvement Project)

6. Rust Pathogen Nomenclature
 The currently accepted names for the three
basidiomycete rust fungi found predominantly on
wheat are:
 Puccinia graminis Pers. f. sp. tritici, the pathogen
of stem rust, also known as black rust;
 Puccinia recondita Rob. ex Desm. f. sp. tritici, the
pathogen of leaf rust, also known as brown rust; and
 Puccinia striiformis Westend. f. sp. tritici, the
pathogen of stripe rust, also known as yellow rust.

9. What is Yellow rust ?
 Caused by Puccinia striiformis
 Host is primarily wheat
◦ Barley and some perennial grasses may be
infected.
 It adversely affects the yield and quality of
wheat grain .
 Seeds produced from stripe rust damaged
crop have low vigor and poor emergence
following germination.

10. More about Rust ???
 Stripe rust pathogen can cause 100%
yield losses in susceptible cultivars if
stripe rust occurs at an early stage and
the infection continues to develop during
wheat’s growth.
 The wide range of yield losses depend
on the susceptibility of wheat cultivar
grown, timing of the initial infection, rate
with which stripe rust develops and
duration of stripe rust infection

11. Pathotype distribution of Wheat
Rusts
 Ten pathotypes of wheat yellow rust were identified in 355
samples from seven states of India, Nepal and Bhutan.
 Population of yellow rust of wheat was virulent to Yr5,
Yr10,Yr13,Yr14,Yr15, Yr26, YrSp and YrSk.
 Owing to the cool and humid weather, increase in the area
under non PBW343 varieties especially HD2967, the
population of pathotype 46S119, which is virulent to Yr9 and
YrA has increased in proportion and was observed in more
than 72% of the samples analyzed so far.
 Pathotype 78S84 which used to be predominant pathotype
prior to 2010 was identified in 3% of the samples only.
( Source: Progress report 2014-15, All India Coordinated
Wheat and Barley Improvement Project)

12. Inheritance of Yr genes 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.
 Genetic analysis showed that segregation of Yr
genes on wheat chromosome 2B complied with
the single dominant gene mode with 3:1 resistant:
susceptible ratio.
 Genes Yr11,Yr12,Yr13, Yr14 and Yr16 are race
specific genes that are expressed only when the
plants are in the adult stages of plant growth.

13. Stripe Rust Disease Cycle

15. Figure : Pustules (sori) of P. striiformis
on wheat leaves

17. Spores germinate at temperatures between 37°F (3°C) and
59°F (15°C), and infection is favored by free moisture (rain
or dew)
Pathogen may be found in “hot
spots” in a field so good monitoring is essential. For
infection to occur, leaves need prolonged wetness,
especially overnight, and temperature
conducive for spore germination and fungal activity.

18. Symptoms
 Stripe rust develops in early spring
favored by cool temperatures and high
humidity.
 Primary symptoms consist of narrow
orange-yellow stripes on leaves,
sheaths, awns and glumes.

19. Disease Assessment

21. Control
 Use of resistant varieties can potentially halt disease
development and secondary inoculum production.
 Destruction of volunteer wheat and other hosts could
reduce the primary inoculum.
 Application of seed dressings and foliar fungicides to
protect the foliage.
 Foliar fungicides such as strobilurins (good
preventative activity) and triazoles (Ergosterol
inhibitors; good post-infection activity) are labeled for
management of stripe rust.
 Protecting the flag-leaf during grain-fill is critical.
 Early spray may require a second spray; late spray
may be too late if infection is rampant.

22. Leaf rust/Stripe rust genes
 Till now, nearly 61 major genes
conferring resistance to stripe rust
(Yr1 to Yr61) have been identified and
designated (Zhou, 2014)
 Most of the identified Yr genes confer
resistance to specific stripe rust races at
seedling stage.
 Race-specific Yr genes confer short-lived
and non-durable resistance in the field due
to the evolution of new virulent races of
stripe rust

23. Resistance Breeding
 It is estimated that, on an average, 10% of the crop is lost due to biotic
stresses annually.
Disease Causal
organism
Occurrence Resistant genes
Yellow or
stripe
rust
Puccinia
striiformis
Westend
sp. tritici
North Western
Plains zone
and North hills
zone of India.
Yr1, Yr2, Yr2ks, Yr3, Yr9 & Yr19
genes.

24. Specific rust resistance genes deployed/available in genetic stocks
registered at NBPGR
Name Registration ID Parentage Salient traits Genes
FKW 1 INGR 06004 UP 2338*4/China
84-40022
Yr & Sr resistance
from Chinese winter
wheat
Lr26/ Sr31/ Yr9,
Yr China 84-
40022
FKW 2 - WH542*4/Yr15(CN
25087)
Yr & Sr resistance Lr26/ Sr31/ Yr9,
Yr15
FKW 3 INGR 06005 PBW343/ HD4672 Complete resistance
to Lr from durum
Unidentified
resistance from
durum
FKW 4 INGR 07004 DWR
1006/PBW343
Lr & Sr resistance
and very high grain
weight
Unidentified
resistance from
durum
FLW 5 INGR 03017 UP2338/Centurk Lr & Sr resistance Lr24 + Sr24
FLW 6 INGR 04011 HP1633/HP1776 Lr & Sr resistance Lr9 + Lr24 +
Sr2 + Sr24
FLW 11 INGR 05003 WH542/Moro Yr & Sr resistance Lr26 + Sr31 +
Yr9

26. Resistance based on the additive
interactions of slow rusting genes
 Selecting parents that lack effective major
genes and have moderate to good levels of
slow rusting resistance to the local rust
patho-types.
 Maintaining genetic diversity. Parents having
different sets of additive genes based on
available information are used in crossing.
 Establishing high disease pressure in the
breeding nursery with chosen rust patho-
types.
 Selecting plants with low to moderate
terminal disease severity in F2 and F3, and
from F4 onwards selecting plants or lines with
low terminal severity.

27. Resistance based on the additive
interactions of slow rusting genes
 Conducting multilocational testing. As
discussed earlier, multilocational testing of
useful advanced lines can indicate the
effectiveness and stability of resistance
across environments. Based on the results,
new lines are identified for future crossing.
 Genetic analyses of selected lines. To
confirm the presence of resistance based on
additive genes, important lines are
genetically analysed.

28. Alien gene transfer
 Several alien transfer involving small chromosome segments or single
genes translocations have made significant contribution towards
development of new wheat varieties.
 One or more group of genes transferred to wheat from some other species
SOURCE OF ALIEN
GENE
TRANSLOCATION GENES
Triticum timopheevii T2B/2G#1 (homologous
recombination)
Sr36./Pm6
Agropyron elongatum 7DS.7DL-7Ae#1L)
(irradiation)
Lr19/ Sr25
A. elongatum 6AS.AL-6Ae# 1L
(irradiation)
Sr26
Secale cereale T3DS. 3DL-3Ae#1S
(spontaneous
translocation)
Lr26/ Sr31/ Yr9/Pm8
Singh and Pawar,

29. Wheat-rye translocations
 Triticale or Triticosecale is the only man-made crop species where whole
genome of rye has been transferred to wheat.
Promising Wheat Rye Translocations (Singh et al., 2011)
Wheat rye
translocation
Source cultivars Desirable features Remarks
1BL-1RS Kavakaz, Veery,
BOW, Lorvin,
Aurora, Alondra
10-15% yield increase,
Lr26/ Sr31/ Yr9/ Pm8, high
productivity, Winter
hardness, Wide adaptation
Present in about
250 wheat
cultivars world
over
1AL-1RS Amigo Sr24, Lr24, Gb2, Pm17 Only used in
USA
 HUW 206, HPW 42, WH 542, UP 2338 & PBW 343, released in 1985, 1991,
1992, 1993 and 1994, respectively) carrying 1BL-1RS translocation.

30. Yellow rust
 Since 2006-07, the stripe rust is occuring in high intensity in one or
other parts of NHZ & NWPZ, is a threat to about 10 million hectares of
North western plains zone and Northern hills zone of India.
 Emphasis was laid for growing rust resistant wheat varieties such as
PBW 550, DBW 17 & WH 542 of bread wheat.
 In 2012-13, the disease was severe in Yamuna belt of Haryana. During
2013-14, farmers have been advised to grow stripe rust resistant
varieties, WH 1105, HD 2967, HD 3086, DPW 621-50, DBW 88, WH
542 especially in NPWZ.
 All varieties with Yr39 & Yr49 are not durable.
 WH 542 - durable resistance against yellow rust.
 WH 1021- Adult plant resistance- Lr & Yr resistance.

31. Overview of Genetic analysis
 Identification of yellow rust resistance
genes and breeding of stripe rust
resistant wheat varieties is an efficient
approach to minimize wheat yield losses
due to stripe rust.
 Therefore, wheat breeders and
pathologists emphasizes on the
development of high yielding and stripe
rust resistant wheat varieties in order to
combat threats created by new stripe
rust races through incorporation of
durable rust resistance with the help of
marker assisted breeding.

32. Marker Assisted Selection
 Marker assisted selection is a useful tool
in combining multiple Yr genes in a
single genotype and in the development
of multi-line cultivars having durable rust
resistance.
 Microsatellites or simple sequence
repeats (SSRs) are DNA sequence
repeats of 1-6 base pairs.
 They are abundant in eukaryotic
genomes and have been commonly
used to facilitate identification and
incorporation of durable resistance

33. Pyramiding resistance genes – one of the
effective approaches to curtail fast emergence
of new, virulent mutants of rust pathogens
 Combinations of resistance genes have
provided good field resistance to wheat
stem rust in Australia for several years.
 In North America, resistance gene
combinations involving Sr2 have provided
durable resistance to stem rust, and Lr13
and Lr34 when combined with other leaf
rust resistance genes also have provided
durable resistance

34. Lr34-Yr18
 In the recent years gene Lr34-Yr18 has
received much attention, because of its
presence in large number of cultivars
throughout the world that have shown durable
resistance to leaf rust and stripe rust.
 Lr34-Yr18 also interact with other slow
rusting genes to enhance the level of
resistance.

35. Case Study

36.  A study was conducted to identify SSR
markers linked to leaf rust resistance
genes Lr24 and Lr28 and to be used for
Marker-Assisted Selection (MAS) to
transfer both genes to a widely cultivated
wheat variety MP 3299 under rainfed
condition.
 F2 individuals of the cross MP 3299×NIL
PBW 343 were used for generating
genotypic data employing closely linked
SCAR markers S73719 and S421570 to
Lr24 and Lr28, respectively, and further
subjected to bulk segregant analysis.

38. Results
 A total of 70 SSR markers that amplify
sequences on long arm of chromosome 3D
and long arm of chromosome 4A were used
for polymorphism assay between the parents
MP 3299 and NIL PBW 343.
 Eighteen SSRs were polymorphic between
the parents, of which 10 were located on
chromosome 3DL and eight on chromosome
4AL.
 Three SSR markers out of 18 polymorphic
markers differentiated two contrasting bulks
and further used for F2 genotyping

39. Some Case Studies

40.  Stripe rust, caused by Puccinia striiformis f. sp.
tritici, is a major biotic constraint to global wheat
production.
 Stripe rust can be effectively controlled by
developing resistant wheat varieties.
 Molecular markers provide a quick way of
detecting rust resistance genes in adapted wheat
material.
 The present study was conducted to investigate
genetic variation for markers linked with stripe
rust resistance genes in 67 Pakistani adapted
spring wheat varieties using 12 pairs of
microsatellite and sequence tagged site markers.

42. •Cluster analysis revealed considerable genetic variation for marker
alleles linked with stripe rust resistance genes .
• Results of this study may be useful for wheat breeders in
pyramiding stripe rust resistance genes in future wheat varieties of
Pakistan through Marker Assisted Selection.

43. Results
 Seventy nine percent wheat varieties showed
marker allele of Xgwm11 associated with stripe
rust resistance gene Yr26, whereas 75% varieties
had the Yr26 linked allele of sequence tagged site
(STS) marker CYS5.
 Stripe rust resistance gene Yr5 was found in 45%,
whereas Yr9 and Yr10 were present in 28%
varieties tested based on the previously reported
linked markers.
 Stripe rust resistance gene Yr17 was found in
10%, whereas Yr18 in 15% of varieties only.


44. CONCLUSION
 The ever changing nature of wheat leaf,
stripe and stem rusts poses a serious threat to
future wheat production.
 Pyramiding of several genes into one cultivar
can be an effective strategy to use resistance
genes to enhance durability of wheat
resistance to leaf and stem rust.
 Molecular description of Lr/Yr genes in
wheat provides a unique biological system to
study the molecular mechanisms of wheat-
pathogen interaction and transduction as well
as the resistance gene function, evolution and
diversity