Conidial anastomosis tubes (CATs) are cells formed from the

conidia A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also ...

(a type of fungal asexual spores) of many filamentous

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

. These cells have a tubular shape and form an

anastomosis An anastomosis (, : anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal (su ...

(bridge) that allows fusion between conidia. CATs and

germ tube A germ tube is an outgrowth produced by spores of spore-releasing fungi during germination. The germ tube differentiates, grows, and develops by mitosis to create somatic hyphae.C.J. Alexopolous, Charles W. Mims, M. Blackwell, ''Introductory My ...

s (germination tubes) are some of the specialized

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...

e (long cells formed by filamentous fungal species) that are formed by fungal conidia. CATs are morphologically and physiologically distinct from germ tubes and are under separate genetic control. Germ tubes, produced during conidial germination, are different from CATs because: CATs are thinner, shorter, lack branches, exhibit

determinate growth In biology and botany, indeterminate growth is growth that is not terminated, in contrast to determinate growth that stops once a genetically predetermined structure has completely formed. Thus, a plant that grows and produces flowers and fruit ...

, and home toward each other. CAT biology is not completely understood. Initially, conidia are induced to form CATs. Once they are formed, they grow homing toward each other, and eventually they fuse. Once fusion occurs, the respective nuclei can pass through the fused CATs from one conidium to the other. These are events of fungal vegetative growth (

asexual reproduction Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the f ...

) and not

sexual reproduction Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote tha ...

. Part of the CAT fusion (

cell fusion Cell fusion is an important cellular process in which several uninucleate cells (cells with a single nucleus) combine to form a multinucleate cell, known as a syncytium. Cell fusion occurs during differentiation of myoblasts, osteoclasts and ...

) have been shown to be a coordinated behaviour.Fleissner, A.; Leeder, A.; Roca M., M.G.; Read, N.D.; Glass, N.L. (2009). Oscillatory recruitment of signaling proteins to the cell tips promotes coordinated behaviour during cell fusion. PNAS. 106(46): 19387–19392. The filamentous fungus ''

Neurospora crassa ''Neurospora crassa'' is a type of red bread mold of the phylum Ascomycota. The genus name, meaning 'nerve spore' in Greek, refers to the characteristic striations on the spores. The first published account of this fungus was from an infestatio ...

'' (a bread mould and fungal

model organism A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Mo ...

) produces CATs from conidia and conidial germ tubes. In contrast, the fungal

plant pathogen Plant diseases are diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like orga ...

, ''

Colletotrichum lindemuthianum ''Colletotrichum lindemuthianum'' is a fungus which causes anthracnose, or black spot disease, of the common bean plant (''Phaseolus vulgaris''). It is considered a hemibiotrophic pathogen because it spends part of its infection cycle as a biotro ...

'', only produces CATs from conidia and not from germ tubes. Fusion between these cells seems to be important for some fungi during early stages of colony establishment. The production of these cells has been suggested to occur in 73 different species of fungi. Roca, M.G., Read, N.D.; Wheals, A. E. (2005). Conidial anastomosis tubes in filamenotus fungi. FEMS Microbiol Lett. 249 (2): 191–198.

References

{{reflist Fungal morphology and anatomy