PARTIAL RESISTANCE TO CROWN RUST

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PARTIAL RESISTANCE TO CROWN RUST
IDENTIFICATION, UTILIZATION AND GENETICS
Marcelo T. Pacheco UFRGS, Brazil Marty L.
Carson USDA-ARS, Cereal Disease Lab.,
U.S.A. Eric W. Jackson USDA-ARS, Aberdeen,
USA James Chong Cereal Research Centre,
Agriculture Agri-Food
Canada
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30º S
Experimental Station (Eldorado do Sul) 45 m
altitude, warm and humid springs
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Natural crown rust epidemic in Brazil
URS 22 high susceptible variety Eldorado do Sul
- 2006
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Partial resistance
A special case of incomplete resistance,
characterized as a low amount of disease
accompanied by a high infection type.
(Parlevliet and van Ommeren, 1975)
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Is there visual signs which can tell apart crown
rust partial resistant genotypes?
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Greenhouse tests may be trick!
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Partial Resistance research at UFRGS

• Started in 1995 followed up the same Partially
  Resistant Population for 8 years
• (1998 2005
  from F2 to F611)
• 2004 ? from the elite segregating material
• selected a set of 34 F7 with
  partial resistance

Based on the pustule phenotype
UFRGS 952681 x UFRGS 17
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Parent
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There is variability for the resistance among the
lines
UFRGS 04B7106-2
UFRGS 04B7115-1
UFRGS 04B7117-3
Flag leaf -1
Flag leaf -1
Flag leaf -1
Flag leaf -2
2006
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General view of experiment including the new 34
partial resistant lines
UFRGS 952681 x UFRGS 17
URS 22
2006
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Grain Yield distribution among the partial
resistant lines and checks
2006
140 bu/acre
2007
Checks
112 bu/acre
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Grain yield correlates well with Stem Rust AUDPC
(Area under the disease progress curve)
2006
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Crown rust partial resistance x Stem Rust Lines
UFRGS 952681 x UFRGS 17
2006
Checks
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GENETICS OF THE PARTIAL RESISTANCE (PR)

• 6 F2 populations

PR Line x URS 22
Susc. parent

• Field Evaluation sequential severity readings
  on individual plants

• Gene number estimated from AUDPC frequency
  distributions

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Pop 1 UFRGS 04B7107-2 x URS 22
04B7107-2 mean 67
F2 mean 509
URS 22 Mean 812
Intermediate F2 84 plants
Susceptible F2 61 plants
Resistant F2 18 plants
4, 3 resistance alleles
2, 1, 0 resistance alleles
6, 5 resistance alleles
Class OBS EXP
Resist. 18 17.8
Interm. 84 89.1
Susc. 61 56.0
Total 163 163
?2 0.7387
DF 2
P 0.69
3 locos hypothesis (additive model)
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Pop 3 UFRGS 04B7111-2 x URS 22
URS 22 Mean 863
F2 mean 387
04B7111-2 mean 30.5
Intermediate F2 115 plants
Susceptible F2 31 plants
5 ,4, 3 resistance alleles
2, 1, 0 resistance alleles
Resistant F2 27 plants
8, 7, 6 resistance alleles
Class OBS EXP
Resist. 27 23.7
Interm. 115 124.3
Susc. 31 25.0
Total 173 173
4 locos hypothesis (additive model)
?2 2.6138
DF 2
P 0.271
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Pop 6 UFRGS 04B7119-2 x URS 22
04B7119-2 mean 0.4
F2 mean 322
URS 22 Mean 872
Intermediate F2 103 plants
Susceptible F2 28 plants
6, 5 ,4, 3 resistance alleles
2, 1, 0 resistance alleles
Resistant F2 25 plants
Class OBS EXP
Resist. 25 26.8
Interm. 103 102.4
Susc. 28 26.8
Total 156 156
10, 9 ,8, 7 resistance alleles
?2 0.1789
DF 2
P 0.91
5 locos hypothesis (additive model)
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Seedling resistance Seedling susceptility
Partial resistant lines show
Felipe Graichen, 2008 (unpublished)
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URS 21 a successful crow rust partial resistant
oat variety from Brazil

• Yield trials from 1996 to 1999
• Released 2000
• High grain
• High grain yield stability
• High milling yield
• Immune to crown rust up to 2004
• Found later it was partially resistant to crown
  rust

2006
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URS 21 is widely adapted
170 bu/acre
28 bu/acre
Grain yield stability analysis using only no
fungicide data, 7 years (2001 - 2007), average of
15 locations / year.
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URS 21 is high grain yielding
86 bu/acre
Grain yield stability analysis using only no
fungicide data, 7 years (2001 - 2007), average of
15 locations / year.
From grain yield stability analysis b linear
regression between grain yield and
environmental index
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Oat Brazilian varieties Comparative grain yields
with and without fungicide spray
90 bu/acre
- Average 2001-2007 at Rio Grande do Sul State -
3 to 6 locations / year ( 5 locations / year)
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Grain yield differences among years (Fungicide
No fungicide)
500 kg/ha 14 bu/acre 1500 kg/ha 42 bu/acre
- 2001-2007 at Rio Grande do Sul State - 3 to 6
locations / year ( 5 locations / year)
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URS 21
?
?
?
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Genetic similarity analysis from the Oat DArt
Consortium
- Method Euclidean Distances - Reduced marker
redundancy
Tinker, 2008, unplublished
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2006 ? identified new set of crown rust partial
resistant lines showing the necrosis/chlorosis
phenotype
Derived from
UFRGS 995078-2 x URS 21
UFRGS 10 X PAUL
C1217 / Coronado-BCRA
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Different lines from cross UFRGS 995078-2 x
URS 21
065037-1
065037-2
065039-3
065043-2
All flag leaves -1
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UFRGS 995078-2 x URS 21
UFRGS 065037-1
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WHAT ELSE ON PR?

• Continue to work on the genetics of PR
• F23 populations (04B71 x URS 22
  ) e new pop. URS 21 x URS 22
• (in collaboration with Dr. Luiz C.
  Federizzi)
• Continue to select for PR in the breeding
  program
• (in collaboration with Dr. Luiz C.
  Federizzi)
• Studying the mechanisms of partial resistance
• microscope analysis of fungal
  development
• (Dr. José A. Martinelli group)
• Study the biochemicals compounds involved in PR
• (in collaboration with Dr. Carla A.
  Delatorre)

• Future molecular mapping of PR the most
  resistant segr. population
• UFRGS 04B7119-2 x URS 22
• (in collaboration with Dr. Luiz C. Federizzi)

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IDENTIFICATION OF NEW SOURCES OF PARTIAL
RESISTANCE Marty L. Carson Cereal Disease Lab -
USDA - Saint Paul, MN
Oat Crown Rust the Pathosystem from Hell

• 90 Pc genes described virulence to all of them
• Sexually recombining pathogen
• Positive virulence associations
• No apparent cost to complex virulence
• Resistant cultivars have a 3-5 yr lifespan

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Problem Identification of partial, non-specific
resistance in the presence of race-specific
resistance genes when corresponding virulence in
the pathogen population is at a low frequency
(Parlevliet, 1983)
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Buckthorn Nursery
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Crown rust sexual stage on the alternarive host
buckthorn
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Screening Putative PR Lines with Inoculum
Specifically Virulent on Them
Bulk Population of P. coronata from Buckthorn
Nursery
Increase Inoculum on Seedlings of Putative PR Line
Inoculate Replicated Field Plots of Putative PR
Lines with Selected Virulent Inoculum
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2007 Mean of 3
Rust Ratings (1-9)
________________________________


Buckthorn Inoculated
Entry
Nursery Nursery Partial,
Non-specific CDC Boyer 4.4 5.2 CI 1712
(Siberian sel.) 5.4
7.3 CI 4706 (La Prevision) 6.5 7.3 CI 7035
(Buck selection 1952) 5.1 7.0 CI 8000 (AR
2-31-20) 5.4 6.0 CI 8429 (66Ab599) 5.9 6.7 PI
260616 (Amarela 5282FB32) 7.8 7.5 PI 266887 (San
Jose) 5.2 6.8 Race-specific Pc68 4.6 3.8
Pc91 7.8 3.5 PI 505014 (MN 866402) 7.7 4.3 Im
mune PI258731 (WIR5201) 9.0
9.0 Checks MN841801 5.4 5.
8 Portage 2.9 4.0 Starter 2.5 2.8 FLSD
(0.05) 0.4 1.3
1 100 severity 9 immune
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What are these sources of Partial Resistance?

• CI1712 (Siberian sel. Canada)
• CI4706 (La Prevision, Argentina)
• CI7035 (Buck sel., Argentina)
• CI8000 (Ark. 2-51-20, US)
• CI8357 (Fla. 65Q1896-97, US)
• CI8429 (66Ab599, Fla., US)
• CI9247 (MN756515, US)
• CI9248 (MN756555, US)
• CDC Boyer (Sask,Canada)

• PI189733 (Nacional 190, Ecuador)
• PI260616 (Amarela 5282 B 32, Brazil)
• PI263412 (Red Algerian 31, Algeria)
• PI266884 (Santa Maria, Portugal)
• PI266887 (Santa Rosa, Portugal)
• IA98822-2 (Iowa State, US)
• GS-7 (Purdue, US)
• CI 8432 (X63-16,Fla., US)

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DEALING WITH THE DEVIL assessing the pathosystem
from hell
Eric W. Jackson USDA-ARS, Aberdeen, USA
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SCHEME
Correct mapping relies on correct population
structure and correct phenotypic and genotypic
data Collection of genotypic data will improve
over the next few years i.e. DArT and Illumina
arrays With regards to collecting phenotypic
data are we doing enough?
2. How can we improve disease assessment?
Example how disease assessment with q-PCR
compares to traditional assessment
1. How can we control variables effecting
disease? Example how Controlled single
isolate poly-cyclic field test compares to
field evaluations Pathogen Environment
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Mapping of a bleach fleck phenotype in the
Ogle/TAM O-031 mapping population an
illustration of the importance in controlling the
pathogen population and environment when
understanding the genetics of crown rust
resistance. - reviewed from Jackson et al.
TAG 116517-527
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FIELD ASSESSMENTS (Ogle x TAM O-301 mapping
population)
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PATOGEN//ENVIRONMENT
USDA ARS Aberdeen single isolate epidemic
assessment - methodology reviewed from Jackson
et al. Phytopathology 971063-1070
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(No Transcript)
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(No Transcript)
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Puccinia coronata race NQMG, Aberdeen, ID 2006
Field races, Castroville, Tx 2006
Ogle TAMO 301 OT-86
OT-30 OT-67 OT-84 OT-37
OT-77
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DISEASE ASSESSMENTS
A
B
A
B
C
C
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TRADITIONAL DISEASE ASSESSMENT
Peterson et al., 1948
Lamari, 2002
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100bp
New Assay (methodology reviewed from Jackson et
al. Plant Dis. 90629-636)
300bp
200bp
100bp
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Mean map positions to RFLP probe RZ543 of a
candidate crown rust resistance gene in Ogle
based on three different assessments of Ogle x
TAMO 301 F68 RILs inoculated with Puccinia
coronata isolate NBFB in both field and
greenhouse experiments (n 4 reps).
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TAMO 301
Ogle
TAMO 301
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IMPROVING THE Assay (methodology reviewed from
Acevado et al. see poster)
FDNA- Provena (S)
ß-actin
FDNA- MN841801 ( R)
Dr. Marecelis Acevedo has eliminated the need to
weight samples prior to DNA extraction by
developing a relative real time qPCR assay using
the original crown rust TaqMan primer probe set
multiplexed with a primer probe set designed to
the beta actin gene from barley.
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CONCLUSIONS
Precise control of pathogen and environment
allowed for correct characterization of the
bleached fleck Disease assessment with q-PCR
improved mapping Data collected from USDA ARS
Aberdeen single isolate field test identified
QTL which were resolved in multilocation field
test.
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Genetics of Partial Resistanceto Crown Rust in
GS 1
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Background

• GS 1 developed by Dr. Greg Shaner, Purdue
  University.
• described as having partial (slow-rusting)
  resistance.
• consistently has low severity of rust (trace to
  20) and MR-MS reaction in field nurseries since
  2003.
• seedling resistant (immune) to many crown rust
  isolates in greenhouse tests.

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Adult-plant resistance (tiny pustules) to crown
rust isolate CR36 in greenhouse.Seedlings of GS
-1 are susceptible to CR36.
AC Morgan
GS 1
Flag leaves
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Genetic Study

• segregating population derived from AC Morgan2/GS
  1 backcross.
• isolate CR36 (previous slide) used to detect
  segregation for adult-plant resistance (APR).
• isolates CR152, CR251, and CR254 avirulent on GS
  1 used to detect segregation for seedling
  resistance.

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Segregation of BCF2 Lines of AC Morgan2/GS1 to
CR254 and CR251 for Seedling Resistance
Isolate Number of lines Expected ratio P
CR254 69 seg 59 sus 1 1 0.50 0.30
CR251 91 seg 37 sus 3 1 0.50 0.30
a dominant gene
one dominant and one recessive
CR251
CR254
AC Morgan x GS 1 F1 x AC
Morgan BC1F1
BC1F2
AC Morgan x GS 1 F1 x AC
Morgan BC1F1
BC1F2
AA dd
aa DD
dd
DD
Aa Dd
AA dd
Dd
dd
1 AA Dd 1 AA dd 1 Aa Dd 1 Aa dd
1 Dd 1 dd
Susceptible
Susceptible
Segregates
Susceptible
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Summary of segregation data of BCF2 of AC
Morgan2/GS 1

• Resistance to CR254 conditioned by a dominant
  gene D.
• Resistance to CR152 conditioned by a recessive
  gene a
• Resistance to CR251 conditioned by genes D and a.
• Expression of recessive gene a inhibited by a
  suppressor gene b present in AC Morgan.
• Suppressor gene b has no effect to dominant gene
  D.

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Since GS 1 also has adult-plant resistance (APR),
e.g., to isolate CR36QuestionIs the low
severity of rust of GS 1 in field a result of
this APR or result of seedling resistance?
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BCF3
BCF4
BCF5
Progenies of single plants tested in field nursery
Lines harvested from field for GH tests
154 plants inoculated with CR152 at seedling
stage
11 lines (a) 6 lines (a, D) 5 lines (a, Dd)
All 22 progenies had severity of rust as GS 1
22 plants resistant
132 plants susceptible
6 lines (D), 13 lines seg, 3 lines sus
89 lines MS or Seg 43 lines susceptible
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Conclusions

• Low severity of rust of GS 1 in the field was
  provided by a single recessive gene.
• Dominant resistance gene likely have some effect
  in lowering rust severity.
• Study is underway to determine whether the
  recessive gene conditions partial resistance
  (durable) or just a case of low frequency of
  virulence in the rust population.

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TAKE HOME MESSAGE

• Some new sources of partial resistance are in
  non-elite genotypes

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THANK YOU