Download Carrot viruses - AHDB Horticulture

Adrian Fox
Carrot viruses
Carrot viruses
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Alfalfa mosaic alfamovirus
Arabis mosaic nepovirus
Beet pseudo-yellows (?) closterovirus
Carrot latent nucleorhabdovirus
Carrot mosaic (?) potyvirus
Carrot mottle mimic umbravirus
Carrot mottle umbravirus
Carrot red leaf luteovirus
Carrot red leaf associated viral RNA
Carrot temperate 1 alphacryptovirus
Carrot temperate 2 betacryptovirus
Carrot temperate 3 alphacryptovirus
Carrot temperate 4 alphacryptovirus
Carrot thin leaf potyvirus
Carrot yellow leaf (?) closterovirus
Cassava green mottle nepovirus
Celery mosaic potyvirus
Celery yellow net (?) virus
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Clover yellow vein potyvirus
Coriander feathery red vein nucleorhabdovirus
Cucumber mosaic cucumovirus
Galinsoga mosaic carmovirus
Heracleum latent trichovirus
Lettuce infectious yellows (?) closterovirus
Oat blue dwarf marafivirus
Okra mosaic tymovirus
Parsnip mosaic potyvirus
Parsnip yellow fleck sequivirus
Poplar mosaic carlavirus
Potato black ringspot nepovirus
Strawberry latent ringspot (?) nepovirus
Tobacco ringspot nepovirus
Tomato black ring nepovirus
Tulip X potexvirus
Parsnip yellow fleck virus (PYFV)
• PYFV carrot isolates to Cow
Parsley reservoirs
• Requires Anthriscus yellows
virus (AYV) for transmission
C/CP• Results from FV382 suggest
this virus is not involved in
internal browning
• Carrot is not susceptible to
AYV
 Direct carrot to carrot
H/P
transmission not a factor
Work carried out under HDC/HortLINK FV228
Carrot red leaf virus (CtRLV)
• Carrot red leaf virus
needed for transmission of
CMD viruses
• Most carrot isolates form a
distinct ‘carrot’ group
• Weed group isolates from:
Carrot
Cow parsley, Hogweed, Pignut,
Sweet Ciceley, Wild Parsnip,
Hemlock, Rough Chervil, Wild Carrot
and Carrot (limited)
 Carrot to carrot major
factor in CMD
Work carried out at Warwick Crop Centre under Defra IF0188
Weed
Simplifying the complex...
Salix spp.
Cow Parsley?
Or
AYV + PYFV
Umbelliferous weeds
Aphids on winter

host
Aphids
Migrate
Carrots under straw??
Pick up
Virus 
Transmit to
Carrot
CtRLV
(CMoV)
(CtRLVaRNA)
Carrots?
Viral browning of carrots (HDC FV382a)
Conventional PCR of
affected & unaffected
carrots showed no
association with
expected viruses
Stocks of carrots rejected due to the
presence of internal necrosis linked to
viruses.
100
90
80
70
samples positive
real-time PCR
demonstrated a
strong association
between CYLV and
necrosis,
suggesting that
removal of this
virus would reduce
necrosis by 96%
affected
60
unaffected
50
40
30
20
10
0
PYFV
CRLV
CRLaV
CMoV
Virus
CYLV
Negative
MiSeq sequencing identified
Carrot yellow leaf virus in
necrotic samples. Sequencing
also detected a Closterovirus
(CtCV) and a Torradovirus
(CaTV) plus 5 other viruses
which were new to science.
2014: tracking down the viruses
2014 : Wild hosts of new viruses
(2012 weed samples)
Species
Hogweed
Cow Parsley
No. of fields No. Of
sampled Samples CaRLV CMoV CaRLaVRNA PYFV CYLV CtCV
CaTV
1
1
1
9
59
(1.7%) (1.7%)
(1.7%)
8
3
7
(25.9%)
(11.1%) (29.6%)
7
27
Hemlock
1
1
Rough Chervil
2
3
1
(33%)
Total
9
90
9
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1
0
1
3
8
0
CaRLV, CMoV & CaRLV = Carrot Motley Dwarf
PYFV = Parsnip yellow fleck virus
CYLV = Carrot yellow leaf virus (NEW - linked to root necrosis)
CtCV = Carrot closterovirus (NEW – similar to CYLV)
CaTV = Carrot toradovirus (NEW – unknown incidence and impact)
2014 Field sampling
(HDC FV 382b + Defra Funding)
• Samples from carrot crops – 100m x 100m blocks
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Sampled in season to assess infection levels and
assess foliar symptom development;
Roots sampled at end of season to assess levels of
necrosis against infection
To be repeated on a broad geographic basis in 2015
Comparative virus health of 3
fields (N.Yorks)
70
60
50
40
Positive
Negative
30
20
10
0
Strensall
Sand Hutton
Sutton on the Forest
Relative virus incidence
between 3 fields (N. Yorks)
High Roans Field
Field Margin and Road
N
208
219
230
241
252
263
274
285
297
308
198
209
220
231
242
253
264
275
286
298
309
199
210
221
232
243
254
265
276
287
299
310
200
211
222
233
244
255
266
277
288
300
311
201
212
223
234
245
256
267
278
289
301
312
202
213
224
235
246
257
268
279
290
302
313
203
214
225
236
247
258
269
280
291
303
314
204
215
226
237
248
259
270
281
292
304
315
205
216
227
238
249
260
271
282
293
305
316
206
217
228
239
250
261
272
283
294
306
317
207
218
229
240
251
262
273
284
295
307
318
23%
25%
9%
Hedgerow
CYLV
CTV
DUAL
197
Ongoing work
• Transmission studies and Koch’s
postulates (HDC)
• Incidence of carrot viruses (HDC)
• Weed hosts of novel carrot viruses
(Warwick samples)
• Defra PhD studentship: The crop
‘virome’:
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Virus ecology of carrot crops
CaTV: Characterisation and
impact
Quantifying the effects of
asymptomatic infection
‘Candidatus Liberibacter solanacearum’
The ‘Zebra chip’ pathogen
‘Candidatus phytoplasma asteris’
Aster Yellows Phytoplasma
SOURCE: Nisbet C, Ross S, Monger WA, Highet F, Jeffries C, 2014. First report
of 'Candidatus Phytoplasma asteris' in commercial carrots in the United Kingdom.
New Disease Reports 30, 16.
Acknowledgements
• This project was carried out with funding from
HDC project FV 382 (a & b)
• Funding from Defra Plant Health Capability is
supporting Zuri Rozado PhD studentship
• Howard Hinds (Root Crop Consultancy Ltd)
• Rodger Hobson (Hobson Farming Ltd)
• Fera staff in Virology, The Molecular
Technology Unit and Applied Genomics team
• Andy Aspin (Bacteriology – Fera)