Iris Yellow Spot Virus -

emerging pathogen and

serious treat for the production

of Allium species

A. Bulajić1, I. Stanković1, A. Vučurović1, D. Ristić1,

K. Milojević1, V. Trkulja2 and B. Krstić1 1Institute of Phytomedicine, Department of Phytopathology,

University of Belgrade-Faculty of Agriculture, Belgrade, Serbia 2Faculty of Agriculture, Banja Luka,

Republic of Srpska, Bosnia and Herzegovina

Iris yellow spot virus (IYSV)

One of 23 distinct species – genus Tospovirus (family

Bunyaviridae)

Genome organization – 3 single-stranded RNA segments of

negative or ambisense polarity

With nucleocapsid protein - form ribonucleoproteins

RNPs are encased within a lipid envelope consisting of two

virus-coded glycoproteins and a host-derived membrane

IYSV gained significance in 1999;

2000 - EPPO Alert List

Comprehensive studies in the EPPO region

and several pest risk analysis conducted by joint

international efforts = IYSV is excluded from EPPO Alert list

Presently - possible economic impact of IYSV in Europe is

considered to be less valuable compared to the cost of

imposing quarantine measures

Considered to be an emerging virus whose world presence

and distribution have recently dramatically increased

Republic of Serbia

IA part I of the Lists of harmful organisms

IA part II (The Law on Plant Health)

http://www.mpt.gov.rs/postavljen/123/bilje1.pdf

Currently – not regulated as quarantine organism

Host range

IYSV

Onion (Allium

cepa)

other

cultivated and

wild Allium

species

Ornamentals:

1. Iris

2.Eustoma

3.Amaryllis

4. Geranium

Monocots

mostly

fam. Liliaceae

For an adult thrips to transmit the virus

has to be acquired by the first or second larval stages

It multiplies in the larvae,

survives through the developmental stages

the emerging adult thrips become infective

Thrips tabaci, onion thrips, is the only

confirmed vector of IYSV

Sirig locality 2007.godina

cv. Stuttgarter

straw-coloured, dry, necrotic spindle- or

diamond-shaped lesions on scapes

Diagnostic symptom

Secondary pathogen - Alternaria sp.

Obrenovac, 2007

Symptoms of little

diagnostic value

Obrenovac, 2007

Symptoms of little

diagnostic value

Eustoma russellianum

Eustoma russellianum

Necrotic ring spots on

the leaves

Leaf necrosis

Whole plant decay

Year Host plant No. of

localities

No. of tested

samples

reference

2005

35 genera of

ornamentals

24 453

Bulajić et al.

(2009) Onion 31 52

2006

14 genera of

ornamentals

16 215

Onion 15 149

2007 Onion 16 189

2008 Onion, leek 11 51

This study 2009 Onion 10 63

2010 Onion, garlic, leek 16 58

2011 Onion, garlic, leek 10 53

Table 1. Overview of the survey on the presence of Iris

yellow spot virus during 2005-2011 in Serbia

Detection methods - serology

47 crops in different localities

Total of 225 samples were collected

including 204 samples of onion (Allium cepa),

13 samples of garlic (A. sativum)

8 samples of leek (A. porrum)

DAS-ELISA kit (Loewe Biochemica, Sauerlach,

Germany),

Detection methods – molecular analyses

conventional reverse transcription (RT)-PCR

132 randomly selected samples –

from all 47 inspected crops, at least two from each locality

Total RNA was extracted using the RNeasy Plant Mini Kit

(Qiagen, Hilden, Germany)

Serbian 605-SRB isolate of IYSV (GenBank Acc. No.

EU586203)

healthy onion, garlic and leek leaves

+/-K

Primer Sequence Amplicon

size (bp)

Reference

IYSV917L

IYSV56U

5’-TAAAACTTAACTAACACAAA-3’

5’-TCCTAAGTATTCACCAT-3’

896

Robène–

Soustrade

et al.

(2006)

IYSV-Pappu1*

IYSV-Pappu2

5’-TAAAACAAACATTCAAACAA-3’

5’-CTCTTAAACACATTTAACAAGCAC-3’

1200

Pappu et

al. (2006)

IYSV-459

TOS-R15

5’-ACCAGAGGAAGCCCGCAG-3’

5’-GGGAGAGCAATYGWGKYR-3’

459

Uga and

Tsuda

(2005)

IYSV-F*

IYSV-R

5’-TCAGAAATCGAGAAACTT -3’

5’-TAATTATATCTATCTTTCTTGG-3’

700

du Toit et

al. (2004)

Table 2. The primers used for IYSV detection in Allium leaves and scapes

IYSV – different primers suitability

Conclusions:

In July 2007, onion plants with distinctive

symptoms - in seed production field in the

Sirig locality (South Bačka District).

Very high disease incidence, estimated at 80%.

Disease occurrence - associated with a high

population of Thrips tabaci.

Conclusions:

Another outbreak - June 2007 in onion bulb crop

in the Obrenovac locality (City of Belgrade

District).

Only two infected onion plants with chlorotic

spots and streaks

Relatively low population of Thrips tabaci.

After IYSV outbreaks in Serbia (Bulajić et al., 2008, 2009)

the measures of thorough eradication were applied

according to Sunsford and Woodhall (2007).

The intensive sampling in the municipalities of Temerin,

especially surrounding locality of Sirig, and Obrenovac

was performed and greater number of samples tested.

No virus presence was detected in any of the tested

samples which proved that IYSV eradication conducted in

2007 was successful.

The eradication performed in Serbia one the successful

examples described in world

There are strong indications that IYSV is spreading

through the region of West Balkans

IYSV should not be underestimated

IYSV was considered to be of a minor importance in the

USA until 2000. After establishment today is one of the

most important viral pathogens of onion

For that reason and due to previous documentation of

multiple introductions in Serbia (Bulajić et al., 2009), the

surveillance for the presence of IYSV must be conducted

in the period to come.

Thank you for your attention