izmir 2014 lesley boyd
TRANSCRIPT
New strategies and technologies in breeding for durable stripe (yellow)
rust resistance in wheat
2nd International Wheat Stripe Rust Symposium, 28th April -1st May 2014,
Izmir, Turkey
Dr Lesley A. Boyd, Research Group Leader, National Institute of Agricultural Botany (NIAB), Cambridge, UK
Informed resistance breedingThe plant recognises universal, common factors produced by the pathogen: PAMPS
Pathogen produces unique effectors that modify the plant environment and suppress plant defence
Disease
Effector-triggered immunity-ETI
Some effectors become Avir genes, recognised by the plant’s R-genes
Pattern-Recognition
Receptor (PRR)
R-gene
PTI and ETI lead to the induction of common defence processes, which include the genes that confer durable, partial, adult plant resistance
PAMP-triggered immunity -PTI
Boyd et al Trends in Genetics 2013
PRR
Informed resistance breedingNon-Host resistance and PTI
ERA-PG project: TritNONHOST (2009-2012) and ERA-CAP project: DURESTrit (2014-2017)
Co-ordinator Dr Patrick Schweizer, IPK, Gatersleben, Germany
TritNONHOST team Patrick’s group
0
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pIPKTA
9
pGY1_
TaPERO
BAC
_632
F23
BAC
_LRR_K
in
pIPKTA
9_LR
R_K
in
pIPKTA
9
pGY1_
TaPERO
BAC
_632
F23
BAC
_LRR_K
in
pIPKTA
9_LR
R_K
in
Re
l. h
au
sto
riu
m in
de
x (
%) Barley-Bgh Wheat-Bgt
Expression of HvRNR8 confers partial resistance in wheat but has no effect in barley
Informed resistance breeding: RNR8 story
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control chitin 60' chitin 180' Control noninfiltrated
TaRNR8 chitin induced
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control 60 Flag 60 Flag180
TaRNR8 flagellin induced
TaRNR8 transcript levels in the wheat cv Renan
Non-Host Resistance summary:
RLKs are a complex group of proteins that potentially play different roles in host- and nonhost interactions
RLKs such as RNR8 may encode upstream components of NHR that escape effector suppression
It may therefore be possible to select or engineer non-host-like pathogen resistance into crops such as wheat
Transgenic wheat lines o/e HvRNR8 and silenced for TaRNR8 will be tested for resistance towards muliple pathogens
Within DURESTrit we have 3 more LRR_RLK with similar transient phenotypes
Identification and exploitation of natural variation in disease resistance
The BBSRC wheat pre-breeding program is divided into 4 pillars (Landraces, Synthetics, Alien Introgression, Elite Wheat) and 2 themes (Phenotyping and Genotyping).
PILLAR 1
Landraces
PILLAR 2
Synthetics
PILLAR 3
Wild
relative
PILLAR 4
Elite
Genotyping
Phenotyping
BBSRC Funded Wheat
breeders
Identification and exploitation of natural variation in disease resistance
• Historically new sources of R-gene resistance have been identified from the 1O, 2O and often the 3O wheat gene pool.
• Within the WISP project, Ian and Julie King at Nottingham University have made over 17,000 crosses between hexaploid wheat and diploid relative.
• At NIAB we have created synthetic hexaploid wheats from crossing tetraploid wheat to Ae. tauschii accessions first characterised by FIGS (Focused Identification of Germplasm Strategy) to identify environmental selection diversity and by DNA markers to determine genetic diversity.
• Simon Griffiths, NRP, Norwich is exploring the 1o gene pool within the Watkin’s landrace collection. e.g. Yr51 (Bariana et al TAG 2013)
• Keith Edwards at Bristol University has developed both SNP array and SNP markers using KASPar technology that support the genomic identification of valuable genetic regions.
•Working with UK wheat breeders these materials are crossed back to elite UK winter wheats.
Informed resistance breeding
In wheat over 60 stripe rust resistance loci have been assigned a Yr designation, while
some 140 QTL for stripe rust resistance have been reported in the literature, located to 49 chromosomal regions
through consensus mapping
(Wellings et al 2013, Rosewarne et al TAG 2013)
Identification and exploitation of natural variation in disease resistance: QTL
How do we identify the Lr34/Yr18/Pm38 complex-like genes, i.e. those that restrict
pathogen invasion, growth and reproduction?
Objective of TritNONHOST
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wheat
barley
powdery mildew
Blumeria graminis f. sp. triticihost: wheat, nonhost: barley
Blumeria graminis f. sp. hordeihost: barley, nonhost: wheat
rust
Puccinia triticinahost: wheat, nonhost: barley
Puccinia hordeihost: barley, nonhost: wheat
blast
Magnaporthe oryzaehost: wheat and barley
new Magnaporthe speciesnonhost: wheat and barley
Jam
es K
olm
er,
USD
A A
RS
General pathogen-regulated genes
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wheatbarley
Blumeria5570
Magnaporthe3252
Puccinia3763
Blumeria4811
Magnaporthe2777
Puccinia10756
The general response of wheat and barley against different pathogen species utilizes common pathways
PAMP-triggered immunity
functional categories in MapMan functional categories in MapMan
1276
1573
Identification and exploitation of natural variation in disease resistance: QTL
MAGIC populations
An innovative approach to dissecting the genetic control
of complex traits in wheat
Alison Bentley, P Howell, J Cockram, G Rose, T Barber, R Horsnell, N Gosman, P Bansept, M
Scutari, A Greenland and I Mackay
Mapping in multi-founder experimental populations
MAGIC
Multi-parent Advanced Genetic InterCross
• Genetically diverse population, bringing-in multiple alleles and allowing for multiple recombination events.
• Good for identifying multiple interacting genetic loci and traits.
• Allows for greater precision in mapping of QTL.
28210315 descendants of Founder 1
The NIAB Elite MAGIC populationFocus on mapping QTL segregating in current elite UK germplasm
Variety Reason for inclusion
Alchemy Yield, disease resistance, soft feed
Brompton 1BL/1RS, hard feed type, OWBM resistance
Claire Slow apical development, soft biscuit/distilling type
Hereward High quality benchmark Gp1 bread making type
Rialto 1BL/1RS, Gp2 moderate bread making type
Robigus High yielding, soft biscuit/distilling type, OWBM resistance
Soissons Early flowering French Gp2 bread making type
Xi19 Facultative, high quality Gp1 bread making type
90K SNP array NIAB Elite MAGIC population
allele freqs in lines
(AAm * 2 + ABm)/((AAm + ABm + BBm) * 2)
Fre
qu
en
cy
0.2 0.4 0.6 0.8 1.0
02
04
06
08
01
00
Potential frequency of an allele in the MAGIC population
Yellow rust resistance in NIAB MAGIC population
22nd August 2011 ‘Warrior’ Pst race
Yellow rust resistance in NIAB MAGIC population
0 1 2 3-4 95-6 7-8
Yellow rust glasshouse seedling test using the ‘Warrior’ race
MAGIC line means
BLUP (log2)
Fre
qu
en
cy
0.0 0.5 1.0 1.5 2.0 2.5 3.0
05
01
00
15
02
00
25
03
00
Parent 1 Hereward
Parent 2 Robigus
Resistant progeny
Yellow rust resistance in NIAB MAGIC populationYellow rust glasshouse seedling tests– distribution of disease scores
BLUP (log2 adjusted scores)
Freq
ue
ncy
Yellow rust resistance in NIAB MAGIC population
Yellow rust field assessment – natural infection
1 2 3 4 5 6 7
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Glasshouse and field (yellow rust) disease scores
field yellow rust
ye
llo
w r
ust se
ed
lin
g te
st
Field YR scores
Seed
ling
YR s
core
s
MAGIC lines showing more yellow rust resistance in the seedling tests than the most resistant founder parent, cultivar Hereward, also showed higher levels of resistance in the field
Yellow rust resistance in NIAB MAGIC populationMapping hits – Yellow rust seedling and field tests
Gp 1 Gp 2 Gp 3 Gp 4 Gp 5 Gp 6 Gp 7 unlinked
-lo
g 10(P
)
Gp 1 Gp 2 Gp 3 Gp 4 Gp 5 Gp 6 Gp 7 unlinked
-lo
g 10(P
)
Seedling resistance
Field resistance
Yellow rust resistance in NIAB MAGIC population
3 large effects observed
0 20
.00
.51
.01
.52
.02
.53
.0
RAC875_c50347_258
genotype class
log
2 y
ello
w r
ust
Estimates(Intercept) 1.0283SNP 1 0.6476SNP 2 0.4223SNP 3 0.4069
SNP 1
SNP 1: “0” allele is associated with lower levels of yellow rust infection, i.e. resistant allele
Favourable alleles are dispersed
Yellow rust resistance in NIAB MAGIC population
Lines showing transgressivesegregation for yellow rust resistance.
Informed resistance breeding: Summary
• There is still potential for the identification of new sources of R-gene resistance with the 1O, 2O and the 3O
wheat gene pool.
• In addition, a better understanding of the primary interaction between pathogen and host (PTI and NHR) could lead to novel targets for resistance breeding.
• While the plant gene targets of effectors and the genetic pathways responsible for resistance provide targets for genetic modification.
Acknowledgements
TritNONHOST team:• Dr. Patrick Schweizer• Jeyaraman Rajaraman
• Dr. Lesley Boyd• Dr. Graham McGrann• Dr. Francesca Stefanato
• Dr. Rients Niks• Dr. Reza Aghnoum• Dr. Sajid Rehman
• Dr. Ulrich Schaffrath• Rhoda Delventhal
Additional collaborators:• Dr. Pete Hedley• Dr. Björn Usadel• Dr. Pamela Abbruscato
Wheat MAGIC population:• Alison Bentley• Phil Howell • James Cockram • Gemme Rose • Toby Barber • Richard Horsnell• Nick Gosman • Pauline Bansept • M Scutari • Andy Greenland • Ian Mackay
Pyramiding disease resistance QTLs:• Mike Grimmer• Sara Clarke • Neil Paveley
PAMP-Triggered Immunity:• Chris Ridout• Hank-jan Schoonbeek
SCPRID team:• Prof. Sakkie Pretorius• Dr . Renee Prins• Dr. Gloudi Agenbag• Dr. Peter Njau• Dr. Godwin Macharia• Dr. Ruth Wanyera• Ms. Ngina Waweru