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Ear and stalk rot
cellular organisms - Eukaryota - Fungi/Metazoa group - Fungi - Dikarya - Ascomycota - Pezizomycotina - Sordariomycetes - Hypocreomycetidae - Hypocreales - Nectriaceae - Gibberella - Gibberella moniliformis
- Gibberella moniliformis (also, Fusarium moniliforme) is a biological species of the mating populations within Gibberella fujikuroi species complex.
- This fungus is primarily a pathogen of maize that causes ear and stalk rot, but it can also cause disease in other crop species.
- The species is an example of facultative endophyte, which can exist in the biotrophic endophytic assocoation with maize as well as saprophytically.
- The fungus is transmitted vertically (spread by growing inside the plant and by infected seeds) and horizontally (spread contagiously through the plant debris and insect vectors and infects plant from outside). The former type of transmission is important because it cannot be controlled by seed applications of fungicides, and maintains the reservoir from which the infection takes place in each generation of plants.
- The fungal infection can result in contamination of the grain with mycotoxins (fumonisins) that can cause severe toxicosis and liver and kidney damage in animals and humans upon ingestion of infected grains.
- Parasitic endophytic fungal growth that progresses asymptomatically is considered to be latent which is not the same as dormant. Hyphae are active physiologically and can produce mycotoxins during asymptomatic infection. Control, prevention, and detection of the endophytic infections by G. moniliformis in corn are difficult, especially because kernels appear to be of good quality.
The stage on which the fungus produces sexual spores is called the teleomorph (or perfect stage), the other, asexual, stage is called the anamorph (or imperfect stage). Gibberella moniliformis anamorph is known as Fusarium verticillioides.
- Endophytic phase
The fungus grows in the biotrophic association with maize;
in this stage the fungus is transmitted vertically, through seed stage;
the fungus endophytically infects seedling from its systemic infection of the seed, usually by the
second day following germination.
growth This is a long-term fungus-plant association during which the pathogen grows without doing substantive harm to its host; toxin production is relatively low at this stage. Some isolates enhanced the growth of maize seedlings. The fungus exists intercellularly, although under certain circumstances can become intracellular.
growth 2-3% seedlings infected through the seed develop the disease and die within 2 to 3 weeks, however, some of them may recover and grow without further symptoms; usually the disease (stalk rot) develops on later stages of the plant growth and induced by conditions that encourage early senescence (water and temperature stress, other diseases); diseased plants take on a grayish green hue then turn tan; pith disintegrates and stalks feel spongy when squeezed.
- Saprophytic phase The fungus grows by using nutrients from decaying debris and soil; on this stage the fungus is spread horizontally, and infection is introduced from outside (through corn silk or injured tissue); this stage can be controlled by application of fungicides.
The vegetative part of a fungus, consisting of a mass of
branching, threadlike hyphae.
Threadlike filaments forming the mycelium of a fungus;
the fungal hyphae localize mostly intercellularly during asymptomatic endophytic phase and
are not disruptive to the structure of the host's
cells (although systemic morphology and histology of the plant is changing); hyphae of
disease-causing strains are found in both intercellular and intracellular sites.
- Conidiophore A specialized hypha that produces conidia. Each conidiophore is ended with a multinucleate vesicle. In G. moniliformis conidiophores are single or branched. Phialides are spherical protuberances that arise from the surface of the vesicle. G. moniliforme is monophialide. Nuclei migrate into the phialides and each mature phialide contains a single nucleus. Phialides produce conidiospores (conidia).
- Hypha Threadlike filaments forming the mycelium of a fungus; the fungal hyphae localize mostly intercellularly during asymptomatic endophytic phase and are not disruptive to the structure of the host's cells (although systemic morphology and histology of the plant is changing); hyphae of disease-causing strains are found in both intercellular and intracellular sites.
A mononucleate vegetative spore; this type of spores
is produced by the fungus in saprophytic stage of its growth; conidia serve for
asexual reproduction and distribution of the fungus horizontally.
There are three types of conidia. Conidia are formed on conidiophore.
On Petri dishes G. moniliformis conidia appear purple gray or pink-purple
- Microconidium Microconidia form chains 5-12 μm in length and 1.5-2.5 μm in width.
- Mesoconidium Short 1-3 septate conidium (may not be observed in G. moniliformis).
- Macroconidium Microconidia form chains approx. 31 μm in length and 3.7 μm in width.
Myung K, Zitomer NC, Duvall M, Glenn AE, Riley RT, Calvo AM. The conserved global regulator VeA is necessary for symptom production and mycotoxin synthesis in maize seedlings by Fusarium verticillioides. Plant Pathol. 2012 Feb 1;61(1):152-160.
Development of symptoms exhibited by 14-day-old Silver Queen maize seedlings. Necrotic lesions, tissue atrophy and mild bleaching or chlorosis on leaves of Silver Queen seedlings grown from seed inoculated with the indicated Fusarium verticillioides strains. Water C, water control; WT, wildtype; Compl, complementation strain. Similar results were obtained with both mating types.
Ma LJ et al. Comparative genomics reveals mobile pathogenicity chromosomes in Fusarium. Nature. 2010 Mar 18;464(7287):367-73.
Phylogenetic relationship of four Fusarium species in relation to other ascomycete fungi and phenotypic variation among the four Fusarium species.
a, Maximum-likelihood tree using concatenated protein sequences of 100 genes randomly selected from 4,694 Fusarium orthologous genes that have clear 1:1:1:1 correlation among the Fusarium genomes and have unique matches in Magnaporthe grisea, Neurospora crassa and Aspergillus nidulans. The tree was constructed with PHYML35 (WAG model of evolution). Branches are labelled with the percentage of 10,000 bootstrap replicates. b–d, Phenotypic variation within the genus Fusarium: b, disease symptoms of (top to bottom) kernel rot of maize (Fv), wilt of tomato (Fol), head blight of wheat (Fg) and root rot of pea (Fs); c, the perithecial states of Fv (Gibberella moniliformis), Fol (no sexual state), Fg (G. zeae) and Fs (Nectria haematococca); and d, micro- and macroconidia of Fv, Fol, Fg and Fs. Scale bars, 10 µm. Fg produces only macroconidia.
- Bacon CW et al. Biological control of Fusarium moniliforme in maize. Environ Health Perspect. 2001 May;109 Suppl 2:325-32.
- Morales-Rodríguez I et al. Biodiversity of Fusarium species in Mexico associated with ear rot in maize, and their identification using a phylogenetic approach. Mycopathologia. 2007 Jan;163(1):31-9.
- Yates IE at al. Effects of Endophytic Infection by Fusarium moniliforme on Corn Growth and Cellular Morphology. Plant Disease / July 1997
- Doctor Fungus: Fusarium moniliforme synopsis
- University of Nebraska-Lincoln: Fusarium Stalk Rot