Biology Reference
In-Depth Information
Virus, Viroid, Phytoplasma -
Pathogens and Diseases
For many years the classification of plant viruses
was in a state of chaos. Fortunately recent bio-
chemical and molecular investigations on orga-
nization and structure of genome as well as on
structural and nonstructural viral proteins pro-
vided enough data to create a definition of spe-
cies. A virus species is a polythetical class of
viruses consisting of replicating lineage and
occupying a particular ecological niche. This
indicated that viruses and biological entities that
possess genes, replicate, interact with hosts and
are exposed to selection pressure, thus specialize
and evolve. Guidelines provided in the Sixth and
Seventh Reports of the International Committee
or the Taxonomy of Viruses are partly followed,
especially by use of a virus species name or
vernacular name for the not fully described
viruses. Following are virus species (including
viroids and phytoplasmas) and virus diseases in
alphabetical order by common names.
an ornamental variety. The bright yellow mot-
tling on green leaves tends to disappear in sub-
dued light. Transmission is by grafting,
occasionally by seed, and, in native Brazil, by
whitefly
Bemisia tabaci
. Plants may recover if
variegated leaves are persistently removed but
may be reinfected.
Albutilon Yellows Closterovirus
Transmitted by Triaulerodes abutilonea. Infected
plants are chlorotic.
Alligatorweed Stunting Closterovirus
Occurs in North America region and Florida.
Alfalfa Mosaic Alfamovirus
Abelia Latent Tymovirus
Potato, Celery Calico; Bean Yellow Dot. Various
strains of the alfalfa virus are transmitted by
cotton, pea, and other aphids to bean, clovers,
pea, cucumber, potato, tomato, zinnia, tumble-
weed, poison hemlock, wild carrot, Japanese
pachysandra, and other hosts. Calico is a minor
potato disease in California and Idaho. Leaf
spots are irregular, brilliant yellow to gray; yield
may be reduced. Celery has a conspicuous
yellow-green mosaic; bean has small, necrotic
lesions.
Symptomless on Abelia; occurs in Eastern USA.
Abutilon Infectious Variegation;
Abutilon Mosaic Bigeminivirus
A single variegated seedling found among green
plants imported into England from the West
Indies in 1868 was propagated vegetatively as
