Fusicoccins are
organic compounds produced by a
fungus. It has detrimental effect on
plants and causes their
death.
Fusicoccins are diterpenoid glycosides produced by the fungus ''
Fusicoccum amygdali
''Fusicoccum amygdali'' is a plant pathogen, which often releases a toxin known as fusicoccin that causes the stomata of the plant to open.
References
External links
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Bot ...
'',
which is a
parasite of mainly
almond
The almond (''Prunus amygdalus'', syn. ''Prunus dulcis'') is a species of tree native to Iran and surrounding countries, including the Levant. The almond is also the name of the edible and widely cultivated seed of this tree. Within the genus ...
and
peach trees. It stimulates a quick acidification of the plant
cell wall
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mech ...
; this causes the
stoma
In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bor ...
ta to irreversibly open, which brings about the death of the plant.
Fusicoccins contains three fused
carbon rings and another ring which contains an
oxygen atom and five carbons.
Fusicoccin was and is extensively used in research regarding the
plant hormone
Plant hormone (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, from embryogenesis, the regulation of organ size, pa ...
auxin
Auxins (plural of auxin ) are a class of plant hormones (or plant-growth regulators) with some morphogen-like characteristics. Auxins play a cardinal role in coordination of many growth and behavioral processes in plant life cycles and are essenti ...
and its mechanisms.
Biosynthesis
Fusicoccin is a member of a diterpenoid class which shares a 5-8-5 ring structure and is called fusicoccane.
In fungi, fusicoccin is biosynthesized via ''Phomopsis amygdali'' fusicoccadiene synthase (PaFS) from universal C5
isoprene
Isoprene, or 2-methyl-1,3-butadiene, is a common volatile organic compound with the formula CH2=C(CH3)−CH=CH2. In its pure form it is a colorless volatile liquid. Isoprene is an unsaturated hydrocarbon. It is produced by many plants and animals ...
units
dimethylallyl diphosphate
Dimethylallyl pyrophosphate (DMAPP; or alternatively, dimethylallyl diphosphate (DMADP); also isoprenyl pyrophosphate) is an isoprenoid precursor. It is a product of both the mevalonate pathway and the MEP pathway of isoprenoid precursor biosynt ...
(DMAPP) and
isopentenyl diphosphate
Isopentenyl pyrophosphate (IPP, isopentenyl diphosphate, or IDP) is an isoprenoid precursor. IPP is an intermediate in the classical, HMG-CoA reductase pathway (commonly called the mevalonate pathway) and in the ''non-mevalonate'' MEP pathway of ...
(IPP). PaFS has two domains, a C-terminal prenyltransferase domain which converts isoprene units into
geranylgeranyl diphosphate
Geranylgeranyl pyrophosphate is an intermediate in the biosynthesis of diterpenes and diterpenoids. It is also the precursor to carotenoids, gibberellins, tocopherols, and chlorophylls.
It is also a precursor to geranylgeranylated proteins, whi ...
(GGDP) and an N-terminal terpene cyclase domain where GGDP gets cyclized and turns into fusicocca-2,10(14)-diene. It is also reported in this study that a 2-oxoglutarate-dependent dioxygenase-like gene, a cytochrome P450 monooxygenase-like gene, a short-chain dehydrogenase/reductase-like gene, and an α-mannosidase-like gene at the 3’ location downstream of PaFS which are responsible for converting fusicocca-2,10(14)-diene into fusicoccin.
Two enzymes, one dioxygenase and PAPT, are in charge of catalyzing a hydroxylation at the 3-position of fusicocca-2,10(14)-diene-8β,16-diol and prenylation of the hydroxyl group of
glucose in fusicoccin P, respectively.
References
{{reflist
Plant physiology
Cyclopentanes
Diterpene glycosides