Published Date: 2003-01-04 23:50:00
Subject: PRO/PL> Sweet potato leaf curl - Peru
Archive Number: 20030104.0020

SWEET POTATO LEAF CURL - PERU
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Date: 4 Jan 2003
From: ProMED-mail<promed@promedmail.org>
Source: Amer Phytopathol Soc, DISEASE NOTES [edited]

First Report of Sweet potato leaf curl virus in Peru.
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S. Fuentes and L. F. Salazar, International Potato Center (CIP), Lima, Peru.
Plant Dis. 87:98, 2003; published on-line as D-2002-1105-02N, 2002.
Accepted for publication 25 Oct 2002.
Leaf curl disease symptoms have been reported in sweet potato (_Ipomoea
batatas_) infected with a geminivirus (1). The disease appeared in Peru
after the 1997 to 1998 El Nino, when the population and activity of
whiteflies (_Bemisia tabaci_, _B. argentifolii_, and _B. afer_) increased.
Approximately 6 percent of plants in commercial fields in San Ramon, Junin
(September 2000) and Canete, Lima (February 2001) showed typical leaf curl
disease symptoms.
17 plants were collected from both places, and stem scions from those plants
were graft-inoculated to _I. setosa_, which developed symptoms of leaf
curling, interveinal chlorosis, and stunting. Total nucleic acid was
obtained from infected sweet potato and _I. setosa_ using
cetyltrimethylammoniumbromide (CTAB) extraction, and primers PW285-3
(5'-CGTCGT TAG CAG TCT GCA GGC CTC CTC TAG-3') and PW285-4 (5'-AAC TGT AAA
TAC GGA ACT GCA GTT CGA ATT-3') for Sweet potato leaf curl virus (SPLCV),
developed and provided by R. Valverde and C. Clark of Louisiana State
University (2), were used to amplify SPLCV by polymerase chain reaction
(PCR).
Expected DNA fragments of ca. 900 bp (in all samples) and 2.4 kp (in some
samples), characteristic of the subgenomic and genomic DNAs of SPLCV
respectively, were obtained from symptomatic but not from symptomless
(uninfected) plants. The 2.4-kb fragment was amplified in relatively small
amounts compared to the 900-bp fragment. Presence of SPLCV was also
confirmed by nucleic acid spot hybridization using a full-length clone of
SPLCV-US.
14 of 17 plants infected with SPLCV were also infected with the
whitefly-transmitted Sweet potato chlorotic stunt virus [SPCSV] (determined
by nitrocellulose membrane ELISA). Both viruses now seem to be common in
farmers' fields in San Ramon and Canete.
To our knowledge, this is the first report of SPLCV in Peru.
References:
(1) P. Lotrakul et al. Plant Dis. 82:1253, 1998.
(2) P. Lotrakul and R. A. Valverde. Cloning of a DNA-A like genomic
component of sweet potato leaf curl virus: nucleotide sequence and
phylogenetic relationships. Molecular Plant Pathology On-Line:
<http://www.bspp.org.uk/mppol/1999/0422lotrakul/paper.htm>
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ProMED-mail
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[SPLCV appears to be an unclassified begomovirus, probably awaiting action
by the Plant Virus Subcommittee of ICTV. The US strain of SPLCV is similar
to viruses reported from Taiwan, Japan, and the Middle East. According to
plant pathologists at Louisiana State University, Baton Rouge, USA, yields
of SPLCV-infected sweet potato crops can be reduced by 10 to 30 percent.
Tuber skin color is darker and tuber skins are marked by grooves. Sweet
potato is ranked seventh in worldwide food production.
URL for Reference No. 2:
<http://www.apsnet.org/pd/pdfs/1998/0915-01R.PDF>
- Mod.DH]
.......................................dh/pg/jw

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