PHYTO MEDIZIN Mitteilungen der Deutschen ... - Die DPG

Identification and characterization of tospoviruses from Iran
A Mehraban, J Saaijer, D Peters, R Goldbach and R Kormelink; Laboratory of Virology,
Wageningen University
During a survey conducted in two provinces of Iran 5 samples of virusdiseased
plant material were collected for further analysis. In all cases large
thrips infestations were observed in the outstanding crop. Four samples were
collected in Teheran province from tomato, chrysanthemum, gazania and
potato, respectively, and one in Gorgan province from soybean. Greenhouse
experiments with several indicator plants revealed symptoms typical for
tospovirus-infections, and in a few cases tospovirus particles were observed
from leaf dip preparations. In subsequent DAS-ELISA experiments none of
the samples reacted with TSWV, TCSV, GRSV, INSV, IYSV and WSMV
antisera indicating that potential new tospoviruses were involved. Vice versa
did none of the known tospoviruses cross react with an antiserum prepared
against the Tomato isolate. To further characterize the Iranian tospoviruses,
the corresponding nucleocapsid (N) genes were RT-PCR amplified and
cloned for nucleotide sequence determination. Alignment of the amino acid
sequence of the N protein of all 5 isolates revealed the presence of two tospoviruses
with almost 10 % sequence divergence. The samples from tomato,
chrysanthemum and gazania were infected with one tospovirus, and soybean
and potate with the other. Both tospoviruses could not only be distinguished
based on their N protein sequence, but also showed differences in symptomatology
on several experimental host plants. For the Tomato isolate the entire
S RNA nucleotide sequence has been determined: it contains 3061 nucleotides
and shows features characteristic for a tospoviral S RNA. Multiple
sequence alignment of the N protein from the tomato isolate with those of
other established tospovirus species revealed the highest homology between
the Tomato isolate and IYSV (74% identity), indicating that the Tomato
isolate should be proposed as a new tospovirus species. Based on the symptoms
on tomato fruit the name Tomato yellow ring virus (TYRV) is proposed.
Changes in the spectrum of PVY strain groups and their involvement in
potato and tobacco diseases
K Lindner 1 and N Billenkamp 2 ; 1 Federal Research Centre for Agriculture and Forestry,
Institute for Plant Virology, Microbiology and Biosafety, Braunschweig and
2
Landesanstalt für Pflanzenbau Forchheim, Rheinstetten
Potato virus Y (PVY) is a member of the Potyviridae, a large and economically
important plant virus family. The three major strain groups of PVY are
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