grapevine viruses - aggie horticulture · 2017-06-05 · olufemi j. alabi & sheila mcbride...

11/10/2016

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Grapevine Viruses

Olufemi J. Alabi & Sheila McBride

TWGGA 2016 Grape Camp

Pioneer Pavilion (Lady Bird Johnson Park)

Fredericksburg, TX

November 6-7, 2016

Viruses infecting Grapevine

•Grapes are hosts to >70 infectious agents globally

•15 families, 26 genera, several unassigned species

•Most possess RNA genomes

•Emergence of viruses with DNA genomes

11/10/2016


Major Virus Diseases

Leafroll

Rugose Wood

Photo: Debra Golino Fanleaf

Photo: Rayapati Lab

Major Virus Diseases

•Redblotch disease is becoming an emerging threat to the sustainability of the US grape industry

Photo: Poojari et al., 2013

11/10/2016


Grapevine Leafroll Disease (GLD)

•Most widespread

•Associated with several distinct closteroviruses

•Most GLRaVs belong to genus Ampelovirus

•Grapevine leafroll-associated virus 3 (GLRaV-3) is predominant

GLRaV-3 (18,498 nt)

p5

GLRaV-2 (16,494 nt)

GLRaV-1 (17,647 nt)

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GLRaV-3 (18,498 nt)

p5

GLRaV-2 (16,494 nt)

GLRaV-1 (17,647 nt)

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Photo: Rayapati Lab

GLD Symptoms: Discoloration

Cabernet Franc

Chardonnay

Photo: Rayapati Lab

Photo: Rayapati Lab

11/10/2016


GLD Symptoms: Leaf Rolling

Merlot

Chardonnay

Photo: Rayapati Lab

Photo: Rayapati Lab

‘Leafroll-like’ Symptoms

P deficiency

GLD Mechanical Injury

Photo: Rayapati Lab

Photo: Rayapati Lab Photo: Rayapati Lab

11/10/2016


Asymptomatic hosts of GLRaVs

Vitis x labruscana ‘Concord’

Vitis labrusca L. ‘Niagara’

GLRaV-3

GLRaV-2SG

Photo: Rayapati Lab

Phenology-based Symptomology

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Data Source:

Rayapati Lab

11/10/2016


GLD: A Disease Complex

LR4-6

LR4-9

LR4-Pr

LR4-Car

GLRaV-7

GLRaV-1

GLRaV-2

LR2-RG

LR4-5

• GLRaV-1 = Grapevine leafroll-associated virus-1

• White font = virus species; Orange font = virus strains

More???

GLRaV-3

GLRaV-4

Photo: Rayapati Lab

Spatial Distribution of GLD

Aggregation of

GLD-affected

vines suggests

spread between

neighbors

• Implicates slow-moving vector and/or root grafting in disease spread

Photo: Rayapati Lab

11/10/2016


Transmission of GLRaVs

Mealybug

Soft scale

Vegetative

cuttings

Photo: B. Bahder

Photo: B. Bahder

Vectors of GLRaVs: CA

Obscure mealybug

Pseudococcus viburni

(= P. affinis)

Citrus mealybug

Planococcus citri

(Risso)

Longtailed

mealybug

Pseudococcus

longispinus

Grape mealybug

Pseudococcus

maritimus

Vine mealybug

Planococcus ficus

Pink hibiscus

mealybug

Maconellicoccus

hirsutus Sourc

e: M

. A

l R

wahnih

11/10/2016


Vectors of GLRaVs: WA

Grape mealybugs

(Pseudococcus maritimus)

Cottony maple scale insects

(Pulvinaria innumerabilis)

•And understanding of virus vector life cycle useful for disease management

Detection of GLRaVs

M Samples (+) (-)M Samples (+) (-)

Serological

assays

(ELISA)

Molecular

assays

(RT-PCR)

11/10/2016


GLD Spread to New Vineyards

Road10 20 30 40 50 60 70 80 90 100

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w #

Vine

#Heavily infected Cabernet Sauvignon block

3 vines in 2008

8 vines in 2009

6 vines in 2010

Total = 17 vines infected

Cabernet Sauvignon (2007)

Road10 20 30 40 50 60 70 80 90 100

1

2 3

4

5

6

7

8 9

10 1

1

Ro

w #

Vine

#Heavily infected Cabernet Sauvignon block

3 vines in 2008

8 vines in 2009

6 vines in 2010

Total = 17 vines infected

Cabernet Sauvignon (2007)

Showing GLRD symptoms in: 2008 2009 2010

Photo: Rayapati Lab

GLD Spread Within Vineyard

GLD incidence = 20%

Photo: M. Al Rwahnih

11/10/2016


GLD Spread Within Vineyard

GLD incidence 5 years later = >60%


Cabernet Sauvignon

Chardonnay

Photo: Rayapati Lab

11/10/2016


Negative Impacts of GLD

‘Healthy’

GLD+

•Reduced fruit load

•Delayed and uneven ripening

•Reduced sugar

• Increased acidity

•Dependent on variety, clone, rootstock, site, season, leafroll type and strain

Grape cv. ‘White’ Emperor

•Mixed infections of multiple viruses often results in

enhanced negative impacts


GLD Effect on OBrix Content

2009

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Date of sampling

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(OB

rix)

Healthy

Infected

* p < 0.05

•Similar trend found across four seasons

Source:

Alabi et al., 2016

11/10/2016


GLD Impact on Wine Quality

Wine Quality

Parameter

% change over

healthy

2010 2011

Total Anthocyanins

(mg/L)

-13.19* -5.76 *

Tannins -26.44* +7.50*

% Ethanol (v/v) -13.06* -5.82*

Photo: Chris Beaver

* Significant at p ≤ 0.001; (-), % decrease; (+), % increase

Healthy Infected

Source: Alabi et al., 2016

Trt

(2010)

Color component* Aroma, flavor Mouthfeel

Purple Red Brown Saturation Red

fruit

Earthy Astringency

Healthy 9.47a 7.36b 0.93b 10.97a 7.01a 4.40b 12.11a

Infected 6.81b 9.01a 1.89a 7.75b 5.01b 5.85a 10.31b

Letters denote significant differences (p ≤ 0.05)

Evaluations by a 12-man sensory-trained panel based on a 15-cm line scale.

11/10/2016


Fanleaf Degeneration and Decline

•Caused by several nepoviruses

•Possess RNA genomes

•Vegetatively transmitted

•Field spread mainly by vectors: longidorid (needle) nematodes

•Associated with fruit yield losses and vine decline

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Nepoviruses: “Nematode Transmitted Polyhedral Virus”

AILV

ArMV

BBLMV

CLRV

GBLV

GARSV

• 16 nepoviruses documented from grapes to date

GDefV

GCMV

GFLV

GTRV

PRMV

RpRSV

TRSV

ToRSV

TBRV

SLRSV http://sdb.im.ac.cn/vide/images/d3.jpg

11/10/2016


Leaf deformation: ‘fanleaf’

Source: M. Al Rwahnih (FPS, UC-Davis)

Yellow mosaic symptoms


11/10/2016


Veinbanding symptoms


Uneven Clusters, Reduced Yield

Healthy Infected


11/10/2016


Rugose Wood Disease Complex

Healthy

Healthy Infected

LN33 stem grooving

(cv. LN33)

Rupestris stem pitting

(cv. St. George)

Infected

Kober stem grooving

(cv. Kober 5BB)

Healthy

Infected

Corky bark

(cv. St. George & LN33)

(So

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Rugose Wood-associated Viruses

• All possess RNA genomes and exists as genetically diverse strains

• Infection not associated with leaf symptoms

GRSPaV

GVA

GVB

GVD

GVE

GVF

Source: Rayapati Lab

11/10/2016


Graft incompatibility

•Graft incompatibility resulting in death of the Cabernet Sauvignon plants was observed in four different rootstocks

•GVF consistently detected in affected vines

Grapevine Redblotch Disease

Source: M. Al Rwahnih

11/10/2016


Grapevine

red blotch

Grapevine

leafroll

Source:

M.R. Sudarshana

(UC-Davis)

Two Diseases, Similar Symptoms

Grapevine redblotch-associated virus

•Posses a circular ssDNA genome

•Three-cornered Alfalfa Hopper, Spissistilus festinus, identified recently as a vector

• Other vectors currently being investigated

Source: Bahder, et al., 2016 Source: M. Al Rwahnih

11/10/2016


GRBaV is widespread in the US

Source: M. Al Rwahnih

GLD-like Impacts of Redblotch

Source: Poojari et al., 2013

11/10/2016


Virus Survey in Texas Vineyards

•Sample collection

• Growers and Viticulture Specialists

•Sample preparation, ELISA and/or RT-PCR

•Gel electrophoresis

11/10/2016


Viruses tested

Virus Assay Present?

GLRaV-1 RT-PCR Yes

GLRaV-2 RT-PCR No

GLRaV-3 ELISA + RT-PCR Yes

GLRaV-4 RT-PCR Yes

GFLV ELISA + RT-PCR No

TRSV RT-PCR Yes

GVA RT-PCR ??

GVB RT-PCR ??

GRSPaV RT-PCR Yes

GRBaV PCR Yes

Blanc du Bois

(GLRaV-3+ )

Photo credit: Fran Pontasch

11/10/2016


Redblotch Symptoms

Photo credit: Fran Pontasch

0102030405060708090

% i

nc

ide

nce

Viruses detected

• Based on analysis of 115 samples

11/10/2016


Predominance of Mixed Infections

Negative

(14.8%) Not tested

(1.7%)

Single virus

(27.8%)

5 viruses

4 viruses

3 viruses

2 viruses

Austin, Hildalgo, Gillespie, Terry,

Harris, Victoria, Lynn, Walker

Austin

Hildalgo

Gillespie

Terry

McClennan

Hockley

Walker

GLRaV-3

GRBaV

11/10/2016


Managing Grape Virus Diseases

•Propagate clean nursery stocks

• Buy only from certified nurseries

•Practice area-wide vector management

• Use IPM tactics: insecticides, parasitoids, mating disruption

•Manage virus alternative hosts

• Free-living grapes in riparian habitats

•Overall goal is to ‘Start Clean’ and ‘Stay Clean’

R&D Needs for a Growing Industry

Disease & Virus

Monitoring

Disease

Impact

Assessments

Education &

Outreach Vector

Management

Study Vector

Biology

Vector

Identification

Clean

Nursery

Stocks

Productive

Vineyard

•Virus disease management will be critical to maintaining a productive vineyard

11/10/2016


Acknowledgements

•Texas Department of Agriculture

•Texas Wine Grape Growers Association

•Anonymous Growers and Viticulture Specialists

•Research Collaborators: TX, CA, WA, NY

grapevine viruses - aggie horticulture · 2017-06-05 · olufemi j. alabi & sheila mcbride...

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