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A perspective on breeding and implementing durable
powdery mildew resistance Lance Cadle-Davidson
Overview
• Feed discussion: How do we ensure future generations can benefit from current efforts in PM resistance breeding? • Encourage: International collaboration to address this
• Share: experience of R-genes in Cornell breeding program • RUN1/REN2 and REN2/REN3
• Update: VitisGen2 genotyping methods for gene stacking
Value of PM resistance (California Raisin grape example, in $millions)
Adoption Lag (Years)
Adoption Rate 10 20 30 40
20% $124M 92 69 51
60% 372 277 206 153
100% 620 461 343 255
Economic incentive to accelerate and increase adoption
(Addresses trade-off between time and quality)
Julian Alston
Kate Fuller
Olena Sambucci
Wine Economics and Policy 3:90-107
Powdery mildew is a problem everywhere
Forces Driving Change: • Embedded vineyards • Costs of pesticides • Costs of fuel, labor • Environmental & Health concerns
• 2003 report from an EU commission:
“viticulture uses 40% of the crop protection products in the whole of agriculture.”
• Powdery mildew management is 10-20% of cultural costs in CA (Wine Economics and Policy 3:90-107)
Slide credit: Bruce Reisch
The rise of low-input grape cultivars
Vidoc, INRA
Merlot Khorus, Univ. of Udine Calardis blanc, JKI
Borsmenta, University of Pécs
More details in Bruce Reisch’s webinar at: www.VitisGen2.org/webinars
The Crystal Ball
How do we protect these genes for future generations? How do we predict the future?
…Data-driven strategies
hiveminer.com
Milgroom, Brewer, Frenkel, Cadle-Davidson, et al.
Pathogen genetics informs host genetics
Eastern U.S.: A center of diversity for Erysiphe necator
Coevolution of pathogen with many mapped PM resistance genes
A crystal ball?
Race specificity: Vitis rotundifolia example (RUN1)
BC
5:3
29
4-R
23
Ma
cc
ab
eu
Po
rta
nT
em
pra
nillo
Sh
ira
z .S
1-1
6S
1-2
0 ;M
2-1
1M
2-2
3T
2-2
4 'P
4-1
P4
-3P
4-4
7 "P
8-9
T8
-5T
8-6*
S9
-2S
9-8
S9
-13 !
P1
0-1
4T
10
-9 +S
11
-1S
11
-5S
11
-6
0
20
40
60
80
100
BC
5:3
29
4-R
23
Ma
cc
ab
eu
Po
rta
nT
em
pra
nillo
Sh
ira
z .S
1-1
6S
1-2
0 'M
2-1
1M
2-2
3T
2-2
4 "P
4-1
P4
-3P
4-4
7 dP
8-9
T8
-5T
8-6 <
S9
-2S
9-8
S9
-13 >
P1
0-1
4T
10
-9 +S
11
-1S
11
-5S
11
-6
0
20
40
60
80
100
BC
5:3
29
4-R
23
Ma
cc
ab
eu
Po
rta
nT
em
pra
nillo
Sh
ira
z iS
1-1
6S
1-2
0 .M
2-1
1M
2-2
3T
2-2
4 lP
4-1
P4
-3P
4-4
7 aP
8-9
T8
-5T
8-6 c
S9
-2S
9-8
S9
-13 t
P1
0-1
4T
10
-9 +S
11
-1S
11
-5S
11
-6
0
20
40
60
80
100
% P
CD
of
fun
ga
l p
en
etr
ate
d e
pid
erm
al c
ell
s%
PC
D o
f fu
ng
al p
en
etr
ate
d e
pid
erm
al c
ell
s%
PC
D o
f fu
ng
al p
en
etr
ate
d e
pid
erm
al c
ell
s
Fig. S3. Feechan et al.
A
B
C
**
****
*
Succ
essf
ul d
efen
se (
%)
RUN1 in vinifera PM Resistant…Eureka!
RUN1 RUN1
Normal PM
The Plant Journal 76:661–674
Race specificity: Qualitative resistance from RUN1
BC
5:3
29
4-R
23
Ma
cc
ab
eu
Po
rta
nT
em
pra
nillo
Sh
ira
z .S
1-1
6S
1-2
0 ;M
2-1
1M
2-2
3T
2-2
4 'P
4-1
P4
-3P
4-4
7 "P
8-9
T8
-5T
8-6*
S9
-2S
9-8
S9
-13 !
P1
0-1
4T
10
-9 +S
11
-1S
11
-5S
11
-6
0
20
40
60
80
100
BC
5:3
29
4-R
23
Ma
cc
ab
eu
Po
rta
nT
em
pra
nillo
Sh
ira
z .S
1-1
6S
1-2
0 'M
2-1
1M
2-2
3T
2-2
4 "P
4-1
P4
-3P
4-4
7 dP
8-9
T8
-5T
8-6 <
S9
-2S
9-8
S9
-13 >
P1
0-1
4T
10
-9 +S
11
-1S
11
-5S
11
-6
0
20
40
60
80
100
BC
5:3
29
4-R
23
Ma
cc
ab
eu
Po
rta
nT
em
pra
nillo
Sh
ira
z iS
1-1
6S
1-2
0 .M
2-1
1M
2-2
3T
2-2
4 lP
4-1
P4
-3P
4-4
7 aP
8-9
T8
-5T
8-6 c
S9
-2S
9-8
S9
-13 t
P1
0-1
4T
10
-9 +S
11
-1S
11
-5S
11
-6
0
20
40
60
80
100
% P
CD
of
fun
ga
l p
en
etr
ate
d e
pid
erm
al c
ell
s%
PC
D o
f fu
ng
al p
en
etr
ate
d e
pid
erm
al c
ell
s%
PC
D o
f fu
ng
al p
en
etr
ate
d e
pid
erm
al c
ell
s
Fig. S3. Feechan et al.
A
B
C
**
****
*
Succ
essf
ul d
efen
se (
%)
Musc4 (Adapted PM)
Normal PM RUN1 in vinifera
PM Resistant…Eureka!
Challenge with PM from Southeast U.S. PM Susceptible…sigh.
RUN1 RUN1
RUN1 RUN1
The Plant Journal 76:661–674
Vitis (2011) 50:173–175
Race specificity: Qualitative resistance from RUN1
BC
5:3
29
4-R
23
Ma
cc
ab
eu
Po
rta
nT
em
pra
nillo
Sh
ira
z .S
1-1
6S
1-2
0 ;M
2-1
1M
2-2
3T
2-2
4 'P
4-1
P4
-3P
4-4
7 "P
8-9
T8
-5T
8-6*
S9
-2S
9-8
S9
-13 !
P1
0-1
4T
10
-9 +S
11
-1S
11
-5S
11
-6
0
20
40
60
80
100
BC
5:3
29
4-R
23
Ma
cc
ab
eu
Po
rta
nT
em
pra
nillo
Sh
ira
z .S
1-1
6S
1-2
0 'M
2-1
1M
2-2
3T
2-2
4 "P
4-1
P4
-3P
4-4
7 dP
8-9
T8
-5T
8-6 <
S9
-2S
9-8
S9
-13 >
P1
0-1
4T
10
-9 +S
11
-1S
11
-5S
11
-6
0
20
40
60
80
100
BC
5:3
29
4-R
23
Ma
cc
ab
eu
Po
rta
nT
em
pra
nillo
Sh
ira
z iS
1-1
6S
1-2
0 .M
2-1
1M
2-2
3T
2-2
4 lP
4-1
P4
-3P
4-4
7 aP
8-9
T8
-5T
8-6 c
S9
-2S
9-8
S9
-13 t
P1
0-1
4T
10
-9 +S
11
-1S
11
-5S
11
-6
0
20
40
60
80
100
% P
CD
of
fun
ga
l p
en
etr
ate
d e
pid
erm
al c
ell
s%
PC
D o
f fu
ng
al p
en
etr
ate
d e
pid
erm
al c
ell
s%
PC
D o
f fu
ng
al p
en
etr
ate
d e
pid
erm
al c
ell
s
Fig. S3. Feechan et al.
A
B
C
**
****
*
Succ
essf
ul d
efen
se (
%)
Southeast PM
RUN1 in vinifera PM Resistant…Eureka!
Challenge with PM from Southeast U.S. PM Susceptible…sigh.
Similarly, within 3 years of introduction, PM in New York could reproduce on RUN1 vines
RUN1 RUN1
RUN1 RUN1
Normal PM
The Plant Journal 76:661–674
Th
om
as
BC
5:3
29
4-R
23
Tra
ys
he
d
e6
-23
e1
-78
JB
81
-10
7-1
1
Th
om
as
BC
5:3
29
4-R
23
Tra
ys
he
d
e6
-23
e1
-78
JB
81
-10
7-1
1
Th
om
as
BC
5:3
29
4-R
23
Tra
ys
he
d
e6
-23
e1
-78
JB
81
-10
7-1
1
0
10
20
30
40
50
60
70
80
90
100
110
** **
** #
# # ** #
#
** #
#
% P
CD
+ + - - - -
+ - + - + -
- - + + - -
- - - - - +
- - + - - -
+ + - - - -
+ - + - + -
- - + + - -
- - - - - +
- - + - - -
+ + - - - -
+ - + - + -
- - + + - -
- - - - - +
- - + - - -
RUN1
RUN1.2a
RUN1.2b
RUN2.1
RUN2.2
NY1-137 LNYM Musc4
Phytopathology 105:1104-1113
RUN1.2a, RUN1.2b, and RUN2.2: Redundant to RUN1?
10dpi growth: 10dpi conidiation:
9 9
3 3 0 0
9 9
5 3 0 0
9 9
5 3 0 0
9 9
5 5 5 5
9=a lot; 5=some; 0=none
Co
lon
y su
cces
s ra
te (
%)
Phytopathology 105:1104-1113
RUN1 and REN2 = additive effects?
Race specificity: Moderate-minor resistance QTL
Vineyard data 1991-2008 Horizon x Illinois 547-1 (V. rupestris B38 x V. cinerea B9)
LOD
REN3
REN2
Reisch, Karn, Cadle-Davidson, et al., unpublished data
Race specificity: Moderate-minor resistance QTL
Vineyard data 1991-2008 Horizon x Illinois 547-1 (V. rupestris B38 x V. cinerea B9)
LOD
REN3
REN2
Reisch, Karn, Cadle-Davidson, et al., unpublished data Molecular Breeding 37:1 Phytopathology 106:1159-1169
Date Chr LOD LOD
Threshold R2
08-25-11 NA NA NA NA
09-17-12 NA NA NA NA
09-25-12 NA NA NA NA
09-17-13 4 3.69 3.40 9.6
15 3.60 3.40 9.4
08-27-14 22 3.97 3.34 11.6
09-03-14 NA NA NA NA
Vineyard data 2011-2014 ‘Horizon’ × V. cinerea B9
REN3
REN2 no longer detectable in vineyard
REN3 race-specific Confirmed in lab
For mapping, phenotype early!
REN2+
REN3+
REN2-
REN3-
REN2-
REN3+
REN2+
REN3-
REN2 and REN3 = additive effects
0-3%
3-12%
12-25%
25-50%
50-100% P
M f
olia
r co
vera
ge
Reisch, Karn, Cadle-Davidson, et al., unpublished data
Acknowledgments: Bruce Reisch, David Ramming, Craig Ledbetter, Andy Walker, Summaira Riaz, Pal Kozma, Matt Clark, Jim Luby, David Gadoury, Bob Seem, Ian Dry, Angela Feechan, Michael Milgroom, Joe Smilanick, Molly Cadle-Davidson, Marianna Kocsis, Paola Barba, Omer Frenkel, Marin Brewer, Raj Majumdar, Siraprapa Mahanil, Sara Lagerholm, Michelle Schaub, Anna Nowogrodzki, Hema Kasinathan, Mary Jean Welser, Paige Appleton, Wei Zhang, Nancy Consolie, Jackie Lillis, Erin Galarneau, Franka Gabler, Surya Sapkota, Avi Karn, and others
Locus Chr Vitis source Race-specific Reference MAS? REN1 13 vinifera Yes Hoffman et al. 2008 Yes REN2 14 cinerea Yes Cadle-Davidson et al. 2016 Yes
REN3 15 complex Yes Welter et al. 2007 Yes
REN4 18 romanetii ? Ramming et al. 2011 Yes REN6 9 piazeskii Pap et al. 2016 Yes REN7 19 piazeskii Pap et al. 2016 Yes
REN9 15 complex Yes Zendler et al. 2017 Yes
REN10 2 complex Teh et al. 2017 Yes
RUN1 12 rotundifolia Yes Feechan et al. 2013 Yes RUN2.1 18 rotundifolia Yes Ramming et al. 2012
new ? aestivalis Yes Ramming et al. 2012
new 7? rupestris Yes Barba et al. 2015
PM resistance in U.S. bunch grape breeding programs
Strong
Strong
Strong
What is AmpSeq? In pictures…for one amplicon
PCR1
PCR2
N7
S5
Pooling, cleanup, QC
NextGen Sequencing
S5 series barcodes identify the sample row
N7 series barcodes identify the sample column
N7 N7
S5 S5
R1
R2
Bc1 Bc2
Imagine this across 384 samples x hundreds of amplicons per sample
S501 S502
N7
01
N
70
2
. . .
. . .
Pool all samples and amplicons in one tube
QC and sequence
Any marker with a sequence basis can be converted to AmpSeq (eg here, simple sequence repeat, SSR)
CLUSTAL O(1.2.0) multiple sequence alignment
1 TCTGAGTCGGAATTTGGAATGTGGTTATGTTGTAGTGGTGGTAGT-----GGTAGTAGTGGTAGTAGTAGTGGTGGTGATGATGATGATGATGAT---AAG…
3 TCTGAGTCGGAATTTGGAATGTGGTTATGTTGTAGTGATGGTAGT-----GGTAGTAGTGGTAGTAGTAGTGGTGGTGATGATGATGATGATGAT---AAG…
9 TCTGAGTCGGAATTTGGAATGTGGTTATGTTGTAGTGGTGGTAGT-----GGTAGTAGTGGTAGTAGTAGTGGTGGTGGTGATGATGATGATGAT---AAG…
33 TCTGAGTCGGAATTTGGAATGTGGTTATGTTGTAGTGGTGGTAGT-----GGTAGTAGTGGTAGTAGTAGTGGTGGTGATGATGATGATGGTGAT---AAG…
314 TCTGAGTCGGAATTTGGAATGTGGTTATGTTGTAGTTGTGGTAGT-----GGTAGTAGTGGTAGTAGTAGTGGTGGTGATGATGATGATGATGAT---AAG…
2 TCTGAGTCGGAATTTGGAATGTGGTTATGTTGTAGTGGTGGTAGT-----GGTAGTAGTGGTAGTAGTAGTGGTGGTGATGATGATGATGATGATGATAAG…
5 TCTGAGTCGGAATTTGGAATGTGGTTATGTTGTAGTGATGGTAGT-----GGTAGTAGTGGTAGTAGTAGTG---GTGGTGATGATGATGATGAT---AAG…
8 TCTGAGTCGGAATTTGGAATGTGGTTATGTTGTAGTGAT-----------GGTAGTGGTAGTAGTGGTGGTGGTGATGATGATGATGATGATGAT---AAG…
10 TCTGAGTCGGAATTTGGAATGTGGTTATGTTGTAGTGGTGGTAGT-----GGTAGTAGTGGTAGTAGTAGTGGTGGTGATGATGATGATGAT[+9]--AAG…
62 TCTGAGTCGGAATTTGGAATGTGGTTATGTTGTAGTGATGGTAGT[+30]GGTAGTAGTGGTAGTAGTAGTGGTGGTGATGATGATGATGAT------AAG…
************************************ * ********* ***** ** *** ** *********** * ***
By electrophoresis, the top 5 alleles would all appear to be the same SSR allele.
Two of the SNPs shown here occur with multiple SSR allele sizes.
Excellent quality data from undetectable quantities of dirty DNA. Analysis of same DNA by SSR capillary electrophoresis was a mess.
In VitisGen1, GBS markers developed from one breeding program did not work in other breeding programs
Jonathan Fresnedo
Shanshan Yang
Side note on marker transferability
Horticulture Research 3:16002
Total bases (Mbp) N50 (kbp) V. cinerea B9 (pacbio) 702 226 V. cinerea B9 (10X) 427 374 V. x doaniana (10X) 472 1767 V. riparia 415 702 V. rupestris B38 (10X) 524 545 Chambourcin (10X) 523 538 Jaeger 70 (10X) 503 292 Concord (10x) 491 324 Norton (454/Illumina) 459 12 Sultanina (Illumina) 544 278 CabSav_v1 (pacbio) 591 2173 Flame (10X) 543 1980
Lance Cadle-Davidson
Jason Londo
Michael Campbell
Dario Cantu
Anne Fennell
Doreen Ware
A core genome to improve transferability: Reference genomes examined
wild
interspecific
vinifera
PN40024 chr9
Cheng Zou
Core genome was built by aligning each genome to PN40024
0
20
40
60
80
100
120
140
160
180
Shar
ed b
lock
s (M
b)
• 10% of the genome is shared among the (imperfect) genomes examined
• 70% of core genome overlaps with genes
Grapevine core genome
8 7 6 5 4 3 2
Genomes
2000 rhAmpSeq markers from core genome
Avi Karn
Cheng Zou
rhAmpSeq compatible with thousands of multiplexed markers
Avi Karn
Cheng Zou
y = 0.78x R² = 0.98
0
50
100
150
200
250
300
350
0 100 200 300 400
Targ
et s
ites
ret
urn
ing
dat
a
# of Amplicons
Data return rates for newly designed amplicons without troubleshooting
Jonathan Fresnedo
rhAmpSeq compatible with thousands of multiplexed markers
Avi Karn
Cheng Zou
y = 0.94x R² = 0.998
0
500
1000
1500
2000
0 500 1000 1500 2000
Targ
et s
ites
ret
urn
ing
dat
a
# of Amplicons
y = 0.78x R² = 0.98
0
50
100
150
200
250
300
350
0 100 200 300 400
Targ
et s
ites
ret
urn
ing
dat
a
# of Amplicons
Data return rates for newly designed amplicons without troubleshooting
Jonathan Fresnedo 1
10
100
1000
10000
100000
1
29
57
85
11
3
14
1
16
9
19
7
22
5
25
3
28
1
30
9
33
7
36
5
39
3
42
1
44
9
47
7
50
5
53
3
56
1
58
9
61
7
64
5
67
3
70
1
72
9
75
7
78
5
81
3
84
1
86
9
89
7
92
5
95
3
98
1
10
09
10
37
1
06
5
10
93
11
21
1
14
9
11
77
12
05
12
33
1
26
1
12
89
13
17
13
45
1
37
3
14
01
14
29
14
57
1
48
5
15
13
15
41
1
56
9
15
97
16
25
16
53
16
81
1
70
9
17
37
17
65
1
79
3
18
21
18
49
18
77
19
05
1
93
3
19
61
19
89
Reads in each Marker
rhAmpSeq compatible with thousands of multiplexed markers
Avi Karn
Cheng Zou
-Lo
g(p
-val
ue)
Physical position (Mb)
GWAS Flower Sex using MLM(PCA+K) model
chr2_4825658
0
5
10
15
20
25
30
35
40
45
0 10 20
Gen
etic
dis
tan
ce (
cM)
Physical position (Mbp)
Chromosome 2
Getting started with AmpSeq
• Make data analysis plan
• Order PCR1 primers with linkers
• Obtain DNA from samples of interest
• Decision point: • In-house: Order PCR2 barcode
primers, multiplex PCR mix, multichannel pipet or robot
• Outsource: Simply send primers and DNA to genotyping facility
ICPP Workshop Sunday, July 29, 2018: Hands-On Analysis of AmpSeq Data
Outreach: AmpSeq workshops
Avi Karn
Jonathan Fresnedo
Strongest R-genes already discovered? New alleles possibly redundant?
~16 R-gene QTL mapped in grapevine Are the strongest effect loci already known?
How many more will we find? Barley: 27 R-gene loci
Wheat: 41 R-gene loci, 60 alleles
Some QTL have additive effects
All are likely race-specific Justification for stacking = additivity and spectrum
Some are redundant Need knowledge of which combinations are useful
Plant Pathology 64: 1396–1406 Crop and Pasture Science 63:997-1006
• Inform strategies: Test combinations of RUN1, REN1, REN2, REN3/9, REN4, REN6, REN7 and REN10. • Example: RUN1, REN1, REN6, REN7 = 16
combinations
Which combinations are useful?
• Inform strategies: Test combinations of RUN1, REN1, REN2, REN3/9, REN4, REN6, REN7 and REN10. • Example: RUN1, REN1, REN6, REN7 = 16
combinations
• Crosses made for 18 of 28 pairs by Clark, Ledbetter, and Reisch
Which combinations are useful?
The lesson of the glass wall
• To learn about how the pathogen will overcome host resistance, plenty of lessons from Fungicide Resistance.
“Those who cannot remember the past are condemned to repeat it.” - George Santayana
Timeline from release to first report of Fungicide Resistance 1973 1977
1982 1985 1989 1990
1997 2003
Lessons from fungicide resistance
High risk: Strobilurins (Group 11); Ridomil products (Group 4); benzimidazoles (defunct Benlate and current Topsin-M, Group 1).
Medium-to-high risk: SDHIs (Group 7); Rovral (Group 2); ametoctradin (one component of Zampro, Group 45); Ranman (Group 21)
Medium risk: DMIs (Group 3); the APs (Group 9; Vangard, Scala, one component of Switch); Quintec (Group 13); Vivando (Group U 08)
Low-to-medium risk: Group 40 fungicides (dimethomorph, one component of Zampro); Elevate (Group 17); fludioxonil (Group 12).
Low risk: Mancozeb, captan, ziram, sulfur, copper, oils, salts
Lessons from fungicide resistance
High risk: Strobilurins (Group 11); Ridomil products (Group 4); benzimidazoles (defunct Benlate and current Topsin-M, Group 1).
Medium-to-high risk: SDHIs (Group 7); Rovral (Group 2); ametoctradin (one component of Zampro, Group 45); Ranman (Group 21)
Medium risk: DMIs (Group 3); the APs (Group 9; Vangard, Scala, one component of Switch); Quintec (Group 13); Vivando (Group U 08)
Low-to-medium risk: Group 40 fungicides (dimethomorph, one component of Zampro); Elevate (Group 17); fludioxonil (Group 12).
Low risk: Mancozeb, captan, ziram, sulfur, copper, oils, salts
Lessons from fungicide resistance
What can we learn from fungicide strategies?
Be honest: the pathogen will win battles; our job is to delay or prevent it from winning the war.
For fungicides
Combine different modes of action
• Often a higher risk with lower risk
Rotate to effective, unrelated chemicals
Limit size of pathogen population
• Don’t use at-risk to rescue
Limit reproduction of resistant individuals
For quantitative resistance, increase dose or activity
Apply best chemicals when disease control is most important.
For host resistance
Combine different mechanisms
• But all are high risk
Cannot rotate
Keep nearby vines disease-free
• Don’t use at-risk to rescue
Limit reproduction of virulent
Cannot increase dose after planted
Apply chemicals after flowering, before pathogen’s sexual phase? Engage pathologists!
Lessons from Wayne Wilcox
• Barley PM: Resistance typically lasts 3 years for individual genes, 5 years for stacked genes. • Exception: mlo effective since 1940s.
• Oat rust (left): Virulence within 1-2 years.
• Quantitative resistance (QR) typically involves at least 4-5 QTL and may be more durable than qualitative resistance (but also exceptions).
• Gene pyramids: redundancy, additive effects, or synergistic mechanisms? • HR + reduce sporulation or ontogenic resistance • Need more info
• Variety mixtures
What can we learn from other crops?
Infect Genet Evol. 2014:446–455
Mol Ecol. 10:1–16
Annu Rev Phytopathol. 14:355–382
Oat rust
• Education: Growers are familiar with fungicide stewardship Develop best practices for managing genetics (built into vine) and chemistry (applied by
grower).
• Patented variety, not otherwise managed • Adding cultural practice requirement is possible, but mechanism usually not exercised.
• Managed varieties (eg SweeTango apple): dictate who and how club varieties are grown • Contractually require growers to conduct certain cultural practices • Lease the vines, with contractual obligations
Legal/educational assets to protect R-genes
Human nature: Ensuring that growers cooperate (apply the requested pesticides, timing, and rates) could be challenging.
Thank you to Peter Cousins, Matt Clark, Bruce Reisch, and Craig Ledbetter for helpful comments!
Limited supply of useful, non-redundant resistance alleles available->need durability.
• Stacking with knowledge of complementarity should be helpful. • Minor resistance effects of genetic background should help as well.
• Annual fungicide application(s) will be critical. • Remove ‘No-spray’ from lexicon. • (Biologicals are a viable option.) • Use education to encourage Annual spray(s). • Manage varieties to mandate Annual spray(s) contractually. • Spray when fruit is susceptible; other sprays will depend on local epidemiology
• Powdery mildew management in nearby blocks will be critical.
• Variety mixtures (different R-gene stacks in adjacent rows) may be helpful.
At Cornell/USDA:
• We can receive other R-genes for standardized phenotyping.
• Need an effort like OsCaR in center of origin, as a crystal ball of best management practices.
My recommendation from this
VitisGen2 Genotyping and PM Goal
Provide germplasm, strategies, protocols, and marker technology (cost-effective and accessible) to make PM resistance breeding easy, efficient, and effective.
VitisGen2 Genotyping and PM Goal
Provide germplasm, strategies, protocols, and marker technology (cost-effective and accessible) to make PM resistance breeding easy, efficient, and effective, and integrated strategies for durability and increased adoption.
Strategies to increase adoption
Acknowledgments
Breeding Team: Bruce Reisch, Lead Lance Cadle-Davidson Matt Clark Anne Fennell Harlene Hatterman-Valenti Chin-Feng Hwang Craig Ledbetter Jason Londo Rachel Naegele Andy Walker
Funding: USDA-NIFA Specialty Crops Research Initiative
Project Number 2017-51181-26829
Genetics Team: Jason Londo, Lead Lance Cadle-Davidson Dario Cantu Qi Sun Peter Schweitzer Anne Fennell
Powdery Mildew Team: Lance Cadle-Davidson, Lead David Gadoury Mark Rea
Executive Committee: Bruce Reisch, Lead Lance Cadle-Davidson Jason Londo Gavin Sacks Tim Martinson Julian Alston
Trait Economics Team: Julian Alston, Lead Olena Sambucci Karina Gallardo Bradley Rickard
Extension and Outreach Team: Tim Martinson, Lead Matthew Clark Michelle Moyer Keith Striegler
Fruit Quality Team: Gavin Sacks, Lead Anna-Katharine Mansfield Rachel Naegele, TG Lead
Project Manager: Fred Gouker
Helpful discussions Peter Cousins, Ian Dry, Ed Buckler