Passionfruit woodiness virus
R. H. Taylor
Victorian Plant Research Institute, Burnley, Victoria, Australia
R. S. Greber
Department of Primary Industries, Indooroopilly, Queensland, Australia
- Described by McKnight (1953) and Taylor & Kimble (1964).
- A virus with flexuous particles about 750 x 12 nm, sap-transmissible to a wide
range of hosts, particularly Leguminosae, and transmitted by at least two species
of aphids in the non-persistent manner.
Causes mosaic (Fig.1
), ringspots, rugosity and distortion of leaves of
(passionfruit); the fruits are frequently distorted and
the pericarp hard and thick (Fig.3
). The productive life of the plants is greatly
decreased. Simmonds (1959)
regarded the disease as the most important disease of
in sub-tropical Australia. However, its importance has
declined since the widespread use of vegetatively propagated plants of the tolerant
hybrid, P. edulis
x P. edulis
. The virus also
occurs naturally in some tropical legumes, including Arachis hypogea, Centrosema
pubescens, Crotalaria usaramoensis, Glycine max
, but is of minor importance in these species.
Reported from the Australian States of Queensland, New South Wales and Western
Australia, and from Surinam (J. J. de Wijs, pers. comm.).
Host Range and Symptomatology
Reported to infect 44 dicotyledonous plant species in five families (Taylor
& Kimble, 1964
; Teakle & Wildermuth, 1967
). Hosts include 10 species of
and 18 in the Leguminosae.
- Diagnostic species
- Passiflora edulis (passionfruit). Mosaic (Fig.1), rugosity and
distortion, with yellow spots on older leaves. The woody fruit symptom (Fig.3)
may also be caused by cucumber mosaic virus or by insect feeding injury and is of
limited diagnostic value.
- Passiflora edulis f. flavicarpa (golden passionfruit) and
P. edulis x P. edulis f. flavicarpa (hybrid passionfruit).
Pale green to chlorotic ringspots occur on spring growth together with leaf
- Phaseolus lathyroides. Inoculated leaves show chlorotic to necrotic
local lesions, followed by systemic infection with leaf epinasty, vein necrosis,
leaf abscission and terminal necrosis.
- Phaseolus vulgaris (French bean). Depending on the cultivar, symptoms
in inoculated leaves range from faint local lesions to veinal necrosis (Fig.5).
In cv. Bountiful the local lesions are chlorotic with normal strains and brown
necrotic with severe strains. The first systemically infected leaves show a faint
mottle which often gives way to a severe blister at a later stage of infection.
In some cultivars necrosis and mottling of the pods occurs.
- Propagation species
- Passiflora edulis may be used to maintain all except the tip blight strain
which may be maintained in the more tolerant host Passiflora suberosa. Phaseolus
vulgaris cv. Bountiful is a good source of virus for purification.
- Assay species
- Small countable, rusty-red ringspots are produced on inoculated primary leaves
of Dolichos biflorus. Chlorotic lesions which may be counted with difficulty
are produced in Phaseolus vulgaris cv. Bountiful. Very small seedlings of
Passiflora edulis or Phaseolus lathyroides are useful for testing
transmission by vectors.
Several strains can be distinguished by severity of symptoms in Passiflora
. Greber (1966)
described a strain which is mild in Passiflora
but causes tip blight and complete loss of crop in Passiflora
. Greber (1971)
described a strain which occurs naturally in
and causes mild mosaic disease in Passiflora
Mild strains effectively cross-protect against virulent strains in
Transmission by Vectors
Transmitted in the non-persistent manner by the aphids Myzus persicae
) and Aphis gossypii
). No other species
have been tested as vectors.
Transmission through Seed
Observations on Passiflora
seedlings grown for experimental or
commercial purposes give no evidence of seed transmission.
Strongly immunogenic. Antisera with titres up to 1/1024 were obtained by
Taylor & Kimble (1964)
by subcutaneous injections of virus in Freunds
adjuvant at several sites followed ten days later by an intravenous injection.
Serological precipitates in mixed liquids occur in a few minutes and are of the
All strains tested appear to be closely related serologically. The virus is
similar to bean yellow mosaic virus
in shape, physical properties and symptoms
in Phaseolus vulgaris
, but it does not appear to be serologically
related to this virus or to the pea mosaic strain of it (Taylor & Kimble,
; Teakle & Wildermuth, 1967
). Its biological and physical properties
place it in the potyvirus
Stability in Sap
In Phaseolus vulgaris
sap the thermal inactivation point (10 min) is
55-60°C, dilution end-point 10-4
inactivation in vitro
occurs in 3-4 days at 18°C.
The virus is stable and is readily purified from inoculated primary leaves of
cv. Bountiful by the following method. Blend each 100 g
of infected leaf tissue in 100 ml phosphate buffer (0.3 M, pH 7.6) containing 0.1%
thioglycollic acid. Squeeze out the fluid through cheesecloth, add n
to 8.5% (v/v), place extract in an ice-bath for 1-2 hr, centrifuge at low speed
and concentrate by ultracentrifugation. To minimize aggregation, resuspend pellets
in borate buffer (0.05 M, pH 8.2) and not in phosphate buffer. Density gradient
centrifugation may be used to purify the virus further. Yields are high compared
with most other potyviruses
. Preparations showing strong birefringence may be
obtained from 200 g leaf.
Properties of Particles
Particles are flexuous filaments about 12 nm wide (Fig.6
). In partially
purified preparations Taylor & Kimble (1964)
found a normal length of 670 nm,
whereas Teakle & Wildermuth (1967)
reported a figure of 745 nm. More recently
R. S. Greber (unpublished) measured the lengths of 100 particles in Phaseolus
sap, using catalase crystals and tobacco mosaic virus
and obtained a figure of 700 nm.
Relations with Cells and Tissues
Pinwheel inclusions and particles occur frequently in the mesophyll and
vascular parenchyma of Phaseolus vulgaris
A woodiness disease of passionfruit was described by Cobb (1901)
but as both
passionfruit woodiness and cucumber mosaic
viruses may cause woody fruit and leaf
mosaic (Taylor, 1959
), the authenticity of records prior to that of McKnight (1953)
is in doubt. However, passionfruit woodiness virus was rare in P. edulis
Queensland in 1927 and widespread in 1932 (Simmonds, 1959
) suggesting that it was
introduced into that State about 1927. Its absence from cool, temperate areas of
Australia and the rare occurrence of cucumber mosaic virus in Queensland suggest
that ecological factors influence the distribution of both viruses.
Experimentally, a mixed infection by the two viruses in P. edulis
a very severe disease (Taylor, 1959
), but naturally occurring mixed infections
are not always so virulent.
To differentiate the two viruses it is best to use the electron microscope; the
filamentous particles of passionfruit woodiness virus are usually readily found
in the sap of infected plants. The diagnosis may then be confirmed by
transmissions to diagnostic hosts. Negative results suggest the presence of
cucumber mosaic virus which, except in mixed infection with passionfruit woodiness
virus, exists in very low concentration in seedlings of Passiflora edulis
and is extremely difficult to transmit to diagnostic hosts by aphid or sap
inoculation. However, when Passiflora edulis scions infected with cucumber
mosaic virus are grafted onto Passiflora caerulea stock the scions develop
a severe necrotic disease and often ultimately die. The virus reaches a high
enough concentration in both stock and scion for transfers to be made from either
to diagnostic hosts.
Passionfruit woodiness virus could be confused with passionfruit latent virus
(Schnepf & Brandes, 1962), which has slightly flexuous particles about 650
nm long, unless care is taken to check particle shape and length. Mixed
infections of the two viruses have not been reported.
A virus reported in passionfruit in Nigeria (Martini, 1962) may be related but
serological evidence is not available.
The use of mild strains to protect plants from more virulent ones in field
conditions was suggested by McKnight (1953) and applied by Simmonds (1959); it
appears to be one of the few instances of this method of control having been
economically useful. More recently, partial control has been obtained by the
use of the hybrid passionfruit which, like its Passiflora edulis f.
flavicarpa parent, produces distorted fruit only under adverse
conditions or when infected with an unusually virulent strain of the virus.
- Cobb, Agric. Gaz. N. S. W. 12: 407, 1901.
- Greber, Qd. J. agric. Anim. Sci. 23: 533, 1966.
- Greber, Qd. J. agric. Anim. Sci. 28: 115, 1971.
- Martini, Ann. appl. Biol. 50: 163, 1962.
- McKnight, Qd. J. agric. Sci. 10: 4, 1953.
- Schnepf & Brandes, Phytopath. Z. 43: 102, 1962.
- Simmonds, Qd. J. agric. Sci. 16: 371, 1959.
- Taylor, J. Aust. Inst. agric. Sci. 25: 71, 1959.
- Taylor & Kimble, Aust. J. agric. Res. 15: 560, 1964.
- Teakle & Wildermuth, Qd. J. agric. Anim. Sci. 24: 173, 1967.
Mosaic in Passiflora edulis.
Ringspots and mosaic in Passiflora edulis x P. edulis f.
Woody fruit of Passiflora edulis.
Pinwheel inclusions and bundles in mesophyll cells of Phaseolus
vulgaris cv. Bountiful. Bar represents 200 nm.
Inoculated leaf of Phaseolus vulgaris cv. Sutters Pink showing
necrotic local lesions and spreading veinal necrosis.
Virus particles from sap of Phaseolus vulgaris cv. Bountiful.
Bar represents 200 nm.