| dc.description.abstract | A Uirus causing systemic chlorotic spot symptom in
spinach (Soinacea oleracea) was characterized and iden
tified as a strain of beet yellows virus and was
referred to as spinach chlorotic spot virus (SCSU). The
virus particles were flexuous and approximately 840 nm
in length. In glasshouse all the beet varieties
(Crimson globe, Eclipe and Detroit) and spinach
varieties (lucullus, Foordhook giant and Swiss chard)
tested were susceptible.
The virus isolate was limited in host range to the
family Chenopodiaceae. In Beta vulgaris. a member of
chenopodiaceae family, systemic necrotic lesions were
observed about 8-10 days after inoculation. The
necrosis was more marked in mature leaves and there was
general intensification of red colour. A few leaves
showed yellow spots and the plants were also stunted.
Necrotic lesions, 2-3 mm in diameter, were also observed
in Chenopodi tim amaranti col or 5 days after inoculation.
Systemic tip necrosis was also observed 2-3 weeks after
inoculation. Chenopodi urn gui noa and C. album showed the
same type of symptoms already described for C.
amaranti col or. White necrotic spots, about 2-3 nm in
diameter, with reddish outline, observed in Gomphrery
xi i i
globosa. Chenopodium amaranticolor was used as an assay
host.
SCSU was successfuly transmitted in a semi
persistent manner by the aphid Myzus persicae. The
virus isolate had a thermal inactivation point (TIP) at o o -4 56 C and not 54 C; dilution end-point (DEP at 10 and -5 not 10 i longevity in in vitro (LIU) at one days and
not 2 days. SCSU was partially purified from infected
spinach leaves by differential centrifugation. The
virus was extracted with 0.1M phosphate buffer, pH 7.2,
and clarified in 72 ether. In homologous reactions, the
virus reacted with its own antiserum to the titre of
1/1024 in nii cropreci pi ti n tests.
On the basis of these criteria and results
obtained, the virus inducing chlorotic spots in
spinach was identified as a strain of beet yellows
virus. | |
