Nothophaeocryptopus Gaeumannii on:
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''Nothophaeocryptopus gaeumannii'' is a species of
Abstract
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fungus
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 ...
that occurs as an endophyte
An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; ...
inside the needles of Douglas-fir
The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is the tallest tree in the Pinaceae family. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Or ...
trees. It is responsible for causing the nonlethal disease known as Swiss needle cast, which results in needle loss and reduction in growth in Douglas-fir.
Traditionally, it has been considered part of family Venturiaceae
The Venturiaceae are a family (biology), family of fungi in the order (biology), order Venturiales. Several of the species in this family are plant pathogens.
List of genera
As accepted by GBIF;
*''Acantharia'' (7)
*''Antennaria'' (2)
*''Ante ...
, but molecular studies have confirmed its placement in Mycosphaerellaceae
The Mycosphaerellaceae are a family of sac fungi. They affect many common plants, such as eucalyptus, the myrtle family, and the Proteaceae
The Proteaceae form a family (biology), family of flowering plants predominantly distributed in the ...
. Three different lineages of ''N. gaeumannii'' are known, each with distinct ecological, morphological, and molecular characteristics.
Distribution
This species of fungus is native to western North America. Remarkably, the disease’s name, Swiss needle cast, arises from the fact that the fungus was first discovered inSwitzerland
Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...
in the 1930s where it was found to be causing disease in plantations of Douglas-fir. It has since been introduced almost everywhere Douglas-fir is grown, and is now widespread in Europe
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
, New Zealand
New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
, and Chile
Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...
. Although the fungus had been known in North America almost since its first discovery, for decades it was not considered to cause disease in its native range, and was largely ignored there until an outbreak occurred in the 1980s and 1990s.
Ecology
''N. gaeumannii'' is anobligate
{{wiktionary, obligate
As an adjective, obligate means "by necessity" (antonym '' facultative'') and is used mainly in biology in phrases such as:
* Obligate aerobe, an organism that cannot survive without oxygen
* Obligate anaerobe, an organism ...
endophyte
An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; ...
of Douglas-fir needles. In the spring, ascospores
In fungi, an ascospore is the sexual spore formed inside an ascus—the sac-like cell that defines the division Ascomycota, the largest and most diverse division of fungi. After two parental nuclei fuse, the ascus undergoes meiosis (halving of ...
infect young needles, briefly growing epiphytically before the hyphae
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 ...
penetrate the needle tissue via stomata
In botany, a stoma (: stomata, from Greek ''στόμα'', "mouth"), also called a stomate (: stomates), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange between the internal air spa ...
. The fungus then spends most of its life cycle
Life cycle, life-cycle, or lifecycle may refer to:
Science and academia
*Biological life cycle, the sequence of life stages that an organism undergoes from conception to reproduction
*Life-cycle hypothesis, in economics
*Erikson's stages of psy ...
growing intercellularly inside the needle. After maturing for approximately nine months, the fungus produces pseudothecia
An ascocarp, or ascoma (: ascomata), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascoc ...
which emerge from the stomata of the needle, dispersing new spores the following spring.
Disease
Normally, when low in abundance, ''N. gaeumannii'' is a relatively benign symbiont of Douglas-fir needles. However, when the fungus is abundant it is responsible for causing the nonlethal disease known as Swiss needle cast. It produces small, spherical black fruiting bodies (pseudothecia
An ascocarp, or ascoma (: ascomata), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascoc ...
) which obstruct the needle’s stomatal openings. The pseudothecia block gas exchange into and out of the needle, which prevents photosynthesis
Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...
in heavily infected needles. This causes yellowing (chlorosis
In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to ...
) of the needles, with eventual necrosis and premature needle-drop. In some heavily infected stands of trees, the only needles remaining are those of the current year, in which the disease has not yet had time to fully develop.
Due to the reduced photosynthesis caused by needle loss, the tree experiences a diminished rate of growth by 52% or more. Increased disease severity tends to occur in climates with mild winters and high humidity where the fungus thrives, and appears to be increasing in severity as a result of climate change
Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
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Gallery
References
External links
* {{Taxonbar, from=Q10625790 Venturiaceae Fungal conifer pathogens and diseases Fungi described in 1936 Fungi of Europe Fungi of North America Fungus species