Fusarium oxysporum f.sp. ciceris
Encyclopedia
Fusarium oxysporum f.sp. ciceris is a fungal
plant pathogen that causes fusarium wilt of chickpea
.
spore
s; macroconidia, microconidia and chlamydospores.
The macroconidia
are straight to slightly curved, slender, thin walled usually with three or four septa, a foot-shaped basal cell and a tapered and curved apical cell. They are generally produced from phialide
s on conidiophores by basipetal division. They are important in secondary infection.
The microconidia
are ellipsoidal and either have no septum or a single one. They are formed from phialides in false heads by basipetal division. They are important in secondary infection.
The chlamydospores
are globose and have thick walls. They are formed from hyphae
or alternatively by the modification of hyphal cells. They are important as endurance organs in soils where they act as inocula
in primary infection.
The teleomorph
or sexual reproductive stage, of F. oxysporum is unknown.
s. It produces enzymes that degrade the cell walls so that gel
s are formed that block the plant’s transport system. Discolouration of the internal tissues progresses from the roots to the aerial parts of the plant, yellowing and wilting of the foliage occur, and finally there is necrosis.
It is possible to identify affected seedlings approximately three weeks after sowing as they display preliminary symptoms such as drooping and pale-coloured leaves
. Later they collapse to a prostrate position and will be found to have shrunken stems both above and below ground level. When adult plants are affected, they exhibit wilting symptoms which progress from the petiole
s and younger leaves in two or three days to the whole plant. The older leaves develop chlorosis while the younger leaves stay a dull green. At a later stage of the disease, all leaves turn yellow. Discolouration of the pith
and xylem
occurs in the roots and can be seen when they are cut longitudinally.
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
plant pathogen that causes fusarium wilt of chickpea
Chickpea
The chickpea is a legume of the family Fabaceae, subfamily Faboideae...
.
Description
Fusarium oxysporum is a common soil inhabitant and produces three types of asexualAsexuality
Asexuality , in its broadest sense, is the lack of sexual attraction and, in some cases, the lack of interest in sex. Sometimes, it is considered a lack of a sexual orientation...
spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s; macroconidia, microconidia and chlamydospores.
The macroconidia
Conidium
Conidia, sometimes termed conidiospores, are asexual, non-motile spores of a fungus and are named after the greek word for dust, konia. They are also called mitospores due to the way they are generated through the cellular process of mitosis...
are straight to slightly curved, slender, thin walled usually with three or four septa, a foot-shaped basal cell and a tapered and curved apical cell. They are generally produced from phialide
Phialide
Phialide .*A flask-shaped projection from the vesicle of certain fungi.*Projects from the mycelium without increasing in length unless there is a subsequent increase in the formation of conidia....
s on conidiophores by basipetal division. They are important in secondary infection.
The microconidia
Conidium
Conidia, sometimes termed conidiospores, are asexual, non-motile spores of a fungus and are named after the greek word for dust, konia. They are also called mitospores due to the way they are generated through the cellular process of mitosis...
are ellipsoidal and either have no septum or a single one. They are formed from phialides in false heads by basipetal division. They are important in secondary infection.
The chlamydospores
Conidium
Conidia, sometimes termed conidiospores, are asexual, non-motile spores of a fungus and are named after the greek word for dust, konia. They are also called mitospores due to the way they are generated through the cellular process of mitosis...
are globose and have thick walls. They are formed from hyphae
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...
or alternatively by the modification of hyphal cells. They are important as endurance organs in soils where they act as inocula
Inoculation
Inoculation is the placement of something that will grow or reproduce, and is most commonly used in respect of the introduction of a serum, vaccine, or antigenic substance into the body of a human or animal, especially to produce or boost immunity to a specific disease...
in primary infection.
The teleomorph
Teleomorph, anamorph and holomorph
The terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota.*Teleomorph: the sexual reproductive stage , typically a fruiting body....
or sexual reproductive stage, of F. oxysporum is unknown.
Symptoms
The fungus enters the vascular system of the infected plant via the rootRoot
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
s. It produces enzymes that degrade the cell walls so that gel
Gel
A gel is a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state...
s are formed that block the plant’s transport system. Discolouration of the internal tissues progresses from the roots to the aerial parts of the plant, yellowing and wilting of the foliage occur, and finally there is necrosis.
It is possible to identify affected seedlings approximately three weeks after sowing as they display preliminary symptoms such as drooping and pale-coloured leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
. Later they collapse to a prostrate position and will be found to have shrunken stems both above and below ground level. When adult plants are affected, they exhibit wilting symptoms which progress from the petiole
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
s and younger leaves in two or three days to the whole plant. The older leaves develop chlorosis while the younger leaves stay a dull green. At a later stage of the disease, all leaves turn yellow. Discolouration of the pith
Pith
Pith, or medulla, is a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which store and transport nutrients throughout the plant. In eudicots, pith is located in the center of the stem. In monocots, it extends also into flowering stems and roots...
and xylem
Xylem
Xylem is one of the two types of transport tissue in vascular plants. . The word xylem is derived from the Classical Greek word ξυλον , meaning "wood"; the best-known xylem tissue is wood, though it is found throughout the plant...
occurs in the roots and can be seen when they are cut longitudinally.