Présentation IIRB 2024 Marine Cordonnier

1. FLAVIE
A collective, multi-stakeholder effort to
propose varietal solutions against virus yellows
79th IIRB – 28/02/24, Marine Cordonnier
28/02/2024

2. 1. Development and establishment of an innovative and efficient
trial protocol to estimate variety yield performance under virus
yellows pressure
2. Identification and characterization of virus yellow
tolerant/resistant varieties in each participant’s germplasms
3. Provide an evaluation of potential genetic answer by sharing
with other PNRI strategies to build new synergic approaches
Out of scope: Common germplasm development
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Principal objectives
Three goals were set at the start of the FLAVIE project

3. Variety
components
Genetic resources
FLAVIE is the top of the iceberg
of a long breeding process
3
FLAVIE project setup and sharing of tasks
Pooling of resources and knowledge, an economy of scale
Yield Field Trials with
Reference protocol
@ 5 to 6 locations
4 treatments/location (Non-Inoc ,BYV, BChV, BMYV)
Methodological experiences
@ 2 to 3 locations
4 treatments/location (BYV+BMYV, BYV+BChV, BChV+BMYV,
BYV+BMYV+BChV)
BYV BMYV
BChV
Shared network of aphids nurseries
Breeding step
(each breeder separately)
Screening step
(all breeders together)

4. Achieved field activities (>55,000 plots)
More than 1,000 hybrids were evaluated with the reference yield protocol
Disease profiles were settled leading to pre-screening of new potential candidates
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0
500
1000
1500
2000
2500
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
2021 2022 2023
#Hybrids
#Plots
Yield plots Disease observation plots Nb of tested hybrids

5. FLAVIE strategy
Maximising virus yellows effect
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High inoculation rate at critical stage
✓Inoculation @ BBCH 12-16 + rather late insecticide application to let infection on-going
✓Aphid Density
• 10 % BYV
• 5 % BMYV & BChV

6. Broad genetic base used to select for virus yellows tolerance
There is large genetic diversity for visual symptoms and yield potential in response to VY
infestation amongst all tested germplasm
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Flavie data : 2023
T1
T2
T3
T4
Average visual score (3 virus)
(1=res to
9=susc)
T1
T2
T3
T4
SHA (absolute value, 3 virus)
Sugar Yield [t/ha]
• Commercial checks rank around the average
• Important variability within each breeder germplasm and for each VY separately
• Good yield potential for each breeder and for each VY
• Similar behavior in response to poleroviruses was observed
• BYV causes higher yield loss compared to poleroviruses
Average visual score
(1=res to
9=susc)
5 2

7. Protocol established and genetic progress
BYV infestation has strongest effect on sugar yield and tested germplasm tends to
improve over the course of the project
• Trial set up leads to significant
yield losses
• Strong & uniform infection of all
plants in the plot
• Very strong yield reduction
(p<0.001) at all locations for all 3
viruses
• Lower impact for poleroviruses
• Improvements in germplasm
tolerance for Virus Yellows
throughout in 2023 (new hybrids
tested each year)
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Flavie data : 2022-2023
Sugar
yield
loss
[%]

8. Different varietal performances were observed
Differences between yield potential, yield losses and scores exist within the tested
hybrids
• Significant variety effects (p<0.001)
• Differences in (BYV example)
i) Yield potential (%checks)
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Sugar Yield [t/ha]-Non Inoculated
Sugar
Yield
[t/ha]-BYV
N100
=
11,7
N100 = 14,9
Flavie data : 2023

9. • Significant variety effects (p<0.001)
• Differences in (BYV example)
i) Yield potential (%checks)
ii) Yield reduction (%)
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Flavie data : 2023
N100 = 14,9 t/ha
Sugar Yield [t/ha]-Non Inoculated
Sugar
yield
loss
BYV
[%]
Different varietal performances were observed
Differences between yield potential, yield losses and scores exist within the tested
hybrids

10. Impact of mixed virus infestation on sugar yield
BYV in the mix creates a synergistic effect and a higher yield loss
• Virus in mix lead to a higher yield
loss than single virus
-> Not a high synergistic effect between polero
• BYV presence in the mix show a
significant yield reduction vs single
virus or polero in mix (p<0.001) ->
points out a synergistic effect
between virus
Limits : tested on a small set of hybrids
(12+4 checks))
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What are the dynamics between viruses
over the growing season ?
Flavie data : 2022-2023 consolidated
Sugar
yield
loss
[%]
-10
-20
-30
-40
Single virus 2 virus 3 virus

11. Estimation of potential genetic progress for VY tolerance
Continuous genetic improvements for VY tolerance
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50
60
70
80
90
100
110
120
2020 2021 2022 2023 2024 2025 2026 2027 2028
Sugar
yield
[t/ha]
NNI or No VY
50
60
70
80
90
100
110
120
2020 2021 2022 2023 2024 2025 2026 2027 2028
Sugar
yield
[t/ha]
NNI or No VY Without Flavie
50
60
70
80
90
100
110
120
2020 2021 2022 2023 2024 2025 2026 2027 2028
Sugar
yield
[t/ha]
NNI or No VY BChV Without Flavie BMYV BYV

12. Conclusions
• We developed an efficient and reliable methodology to characterize varieties in
strong VY presence (single and mix virus inoculations).
• Clear differences were observed between poleroviruses and BYV, being BVY
alone or in combination with the other viruses the one with a bigger impact on
yield performance.
• Several sources of tolerance against the 3 viruses with various yield potential in
non-inoculated conditions have been identified.
• Need to identify additional resistance sources to ensure sustainable levels of
combined tolerance against the VY complex.
• Breeding is one major factor but must be accompanied with other measures
(crop rotation, foliar insecticides, biocontrol, etc.)
-> Interaction with the other PNRI projects
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13. Thanks for your
attention
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