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 Aphid
and Whitefly-borne Viruses of Sweet Potato
INVESTIGATOR: Valverde, R. A.
PERFORMING INSTITUTION:
Plant Pathology & Crop Physiology
Louisiana State University
Baton Rouge, Louisiana 70803
NON-TECHNICAL SUMMARY: Most sweet potato viruses have
not been well characterized. The main objective of this
investigation is to characterize selected sweet potato
viruses and develop practical diagnotic tools.
OBJECTIVES: To conduct biological and molecular
characterization of whitefly-borne criniviruses and
potyviruses from sweet potato. To study the effect of single
and mixed infections, and host on transmission efficiency of
aphid and whitefly-borne viruses of sweet potato. To develop
and/or test laboratory methods for practical and reliable
detection of begomoviruses and criniviruses. To study the
genetic variability among sweet potato leaf curl virus
isolates from different geographical locations.
APPROACH: Molecular and biological characterization
will be conducted using selected isolates of several viruses
from sweet potato. Insect transmission experiments will be
conducted using colonies reared in the laboratory. Various
methods for nucleic acid extraction from plant tissues will
be tested to develop practical detection tools. The sequence
of a 457 nucleotide fragment of the AC1 gene of isolates of
sweet potato leaf curl virus will be compared to determine
their genetic variability.
PROGRESS: 2004/01 TO 2004/12
Investigations on the genetic variability and diagnosis of
Sweet potato leaf curl virus (SPLCV) were conducted in
collaboration with scientists in Spain and Thailand. DNA
samples, suspected to be infected by SPLCV, were collected
from sweet potato plants in Spain and tested in Louisiana
for the presence of SPLCV by molecular hybridization using
virus specific probes. The coat protein (CP) gene of
selected positive samples was cloned and sequenced. Results
of sequence analyses suggest that a previously undescribed
sweet potato geminivirus is present in Spain, together with
SPLCV. Similar studies are under way using several SPLCV
isolates obtained from breeding lines from various locations
in the United States. The data from Spain, together with
preliminary data obtained in the United States, support the
hypothesis of sweet potato leaf curl disease being caused by
several species of whitefly-transmited geminiviruses.
Collaboration with scientists in Thailand resulted in the
production of primers that amplify the CP gene of the United
States isolate of SPLCV. The CP gene of this SPLCV isolate
was amplified and cloned using the designed primers. The
goal of this ongoing research is to produce SPLCV-specific
antiserum using the CP expressed in vitro. Antiserum will be
used in serological tests not only to detect SPLCV but
related sweet potato geminiviruses as well.
IMPACT: 2004/01 TO 2004/12
The increase knowledge on the genetic variability and the
development of practical detection methods for geminiviruses
infecting sweet potato will provide useful tools for the
development of control strategies for the diseases they
cause.
PUBLICATIONS: 2004/01 TO 2004/12
1. Valverde, R and Moreira, M. A. 2004. Identification of
sweet potato (Ipomoea batatas.L) viruses in Costa Rica.
Agronomia Mesoamericana 15:1-7.
2. Valverde, R. A., Sim, J., and Lotrakul, P. 2004. Whitefly
transmission of sweet potato viruses. Virus Research
100:123-128.
3. Valverde, R. A., Lozano, A. G., Navas-Castillo, J.,
Ramos, A., and Valdez, F. 2004. First Report of Sweet potato
chlorotic stunt virus and Sweet potato feathery mottle virus
infecting sweet potato in Spain. Plant Dis. 88: 428.
4. Lozano, G., Nunez, A., Valverde, R., and Navas-Castillo,
J. 2004. Begomoviruses infecting sweet potato in Spain
(poster). In: Proceedings, 2nd European Whitefly Symposium.
October 5-9, Cavtat, Croatia.
PROJECT CONTACT:
Name: Valverde, R. A.
Phone: 225-578-1384
Fax: 225-578-1415
E-mail:
rvalverde@agcenter.lsu.edu
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