Durable Powdery mildew resistance in grapevines: myth or reality - - PowerPoint PPT Presentation

durable powdery mildew resistance in grapevines myth or
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Durable Powdery mildew resistance in grapevines: myth or reality - - PowerPoint PPT Presentation

Durable Powdery mildew resistance in grapevines: myth or reality Summaira Riaz University of California, Davis Photo: NMSU Photo: Peter Magare Integrative approach Identification of resistance and marker development Durable Pathogen


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Durable Powdery mildew resistance in grapevines: myth or reality

Photo: Peter Magare Photo: NMSU

Summaira Riaz University of California, Davis

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Pathogen biology Identification

  • f resistance

and marker development Mechanisms

  • f

resistance Breeding (MAS)

Integrative approach

Durable field resistance

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PM resistance loci in breeding program

  • Ren1
  • V. sylvestris/vinifera

chr13 Ren1

  • Run1, Run2
  • M. rotundifolia

chr12

Run1

  • Ren6
  • Ren7
  • V. piasezkii
  • Ren4
  • V. romanetii

chr9 chr19

Ren6 Ren7

chr18

Ren4 Run2

Other loci: Ren2 (V. cinerea B9) Ren3 and Ren9 (American spp hybrid, Regent) Ren8 (Villard blanc) Ren10 (Seyval blanc)

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PM Breeding program at UC Davis

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09314-102 09338-016 09331-047 07355-075 09356-235

  • PdR1 locus from b43-17
  • Chr14, MAS breeding
  • Field trials and wine tasting
  • Nursery release in 2017
  • Public release in 2020

Summary

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Constant field evaluations

Isolate collection -- Summer 2016

  • 13352-57-A = BC1 population with Ren6 locus

(infected leaves)

  • 14370-37-C = Pyramid cross with 3 loci (infected

berries and rachis)

  • Carignane= C- isolate (infected leaves)
  • In vitro leaf assay
  • Greenhouse grown plants
  • Categorical scoring (1 – 5 scale)
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11373 population retesting

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2014 2017

A B

QTL analysis comparisons

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Does combining loci with similar mechanisms of resistance improve overall resistance?

a b c c

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What we have learned, what we don’t know?

  • Multiple loci to breed
  • Isolate specificity of different loci
  • Understanding of pathogen biology
  • How quickly do virulent isolates originate or

evolve?

  • Monitoring the spread of virulent isolates
  • Resistant loci are not surety for complete

eradication of PM

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Conclusions

  • Preventive sprays in the beginning and end of season
  • Worth testing superior parental selections with wide

range of isolates

  • Understanding of mechanisms of resistance and how

underlying genes function is important – core set of effectors

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Team Powdery mildew

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Thanks!

Funding Sources: American Vineyard Foundation,

Louise Rossi Endowed Chair in Viticulture