Diseases and Management of Crops under Protected Cultivation

(Diseases and Management of Crops under Protected Cultivation)
Endoplasmic Reticulum: Membranes that pervade the cell, seemingly not associated with any of
the structures listed above. If ribosomes are clustered along these membranes is called rough ER.
Ribosomes: dot-like structures often associated with endoplasmic reticulum.
Meristematic cells in roots parenchyma
from Glycine hispida (10000X)
Chloroplast in Leaf Material
Thicker ascospore walls (TEM) fungus
Infectious Agent
TEM of phytoplasma colonizing
the phloem of an infected stem.
A complete treatise of ultrastructural detail of infectious agents is beyond the scope of this
presentation. Generally speaking, it is easy to get carried away describing these organisms in any
detail, especially protozoa. It is better to describe the essentials, interpret and continue.
Viral
In describing viruses, describe size if a scale marker is present, shape, encapsulated or
not, appearance of nucleoid, and where virus is present (intranuclear, budding from cell
membranes/ walls, within er, extracellular, etc.).Some viruses are more easily identified
ultrastructurally than others:
Poxviruses- relatively large viruses (200-300 nm), replication in the cytosol unlike most
DNA viruses, substantial capsule and dumbbell-shaped nucleoid.
Adenoviruses- characteristic intranuclear paracrystalline array.
Herpesviruses- replication in nucleus where immature nucleocapsids are present, envelope
by budding through a membrane (often nuclear, sometimes er or plasma membrane).
Bacterial
Be familiar with general ultrastructural morphology of a bacterium. Knowing the species of
plant / animal, the tissue involved, and occasionally some other features, you can make an
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