Allodus podophylli
| Allodus podophylli | ||||||||||||
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Aecien of Allodus podophylli on the underside of a shield-shaped foot leaf |
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| Scientific name of the genus | ||||||||||||
| Allodus | ||||||||||||
| Arthur | ||||||||||||
| Scientific name of the species | ||||||||||||
| Allodus podophylli | ||||||||||||
| ( Pig. ) Arthur |
Allodus podophylli ( Syn. Puccinia podophylli ) is a stand fungal art from the order of the rust fungi (Pucciniales). The fungus forms yellowish and brownish spore beds on the shield-shaped foot leaf ( Podophyllum peltatum ), which itattacksas an endoparasite . Its distribution coincides with that of the host and includes temperate eastern North America . Allodus podophylli does not change host and forms spermogonia , aecia and telia from spring to summeron the same host species.
The species was first described in 1822 by Lewis David von Schweinitz . After being listed as a representative of the genus Puccinia for a long time , it is now the only species of the genus Allodus . It branches off relatively early in the family tree of the suborder Urediniae and is not closely related to Puccinia .
features
Macroscopic features
The spore beds of Allodus podophylli are relatively inconspicuous, but stand out due to the discoloration of the surrounding epidermis . The aecia and spermogonia grow on round to ellipsoidal, yellow leaf spots 3–10 mm in diameter. These spots can be sparsely to gregariously distributed on the leaves. The orange-yellow aecia usually break out on their underside as round and cup-shaped, orange-yellow hillocks. They soon take on a brittle, powdery consistency. The spermogonia of the species grow opposite the aecia on the upper side of the leaf and can be seen as golden-yellow, spherical to flat-spherical warts. Allodus podophylli does not own Uredien . The dark brown Telien the type grow individually or socialize on yellow leaf spots, discolored areas of the stems or the sepals , sometimes together with Aecien and spermogonia. First they grow under the epidermis, later they protrude from it. Over time, they become powdery and often grow together.
Microscopic features
Like all rust fungi , Allodus podophylli grows intercellularly, i.e. between the tissue cells of its host. The fungus forms suction threads, so-called haustoria , which penetrate the mesophyll cells of the plant. Aecia and telia can arise in parallel from the same mycelium , but they each have their own suction threads, which also differ significantly morphologically. The up to 300 microns wide Aecien the type can be under the microscope from 29.0 to 35.0 × 24.0 to 30.0 microns wide, typically rhombic Peridienzellen recognize. The outer walls are wrinkled and the inner walls are dotted. The aeciospores are 25.5–32.0 × 22.5–29.0 µm in size and are formed in chains. Their shape varies between spherical, ellipsoidal and irregularly polyhedral. Both its interior and its roughly 1 µm thick walls are hyaline (colorless, translucent). Young aeciospores have a smooth surface; older specimens usually have fine warts. Each of them usually has five prominent germ pores. The spermogonia reveal fine-pored fiber tissue in a microscopic view. Their diameter can be estimated at around 130–160 µm. The hyaline spermatia of the fungus reach a size of 8.0–10.5 × 3.0–5.0 µm and are ellipsoidal to egg-shaped to kidney-shaped. Your wall is smooth. Allodus podophylli has 37.0–59.0 × 16.0–27.0 µm teliospores with two cells. They have an ellipsoidal or club-like shape and are truncated at the top, while they can also be slightly pointed at the base. At the level of the septum , they can be slightly constricted or untapered. The teliospores are dark brown in color and have 1–2 µm thick walls. Their surface is sparsely covered with up to 7.5 µm long, sometimes hook-shaped spines. The stalks of the teliospores are elongated, round and up to 9.5 µm long. They are fragile, thin and often still cling to the detached spores in remnants.
distribution
The distribution area of Allodus podophylli coincides completely with that of the only known host, the shield-shaped foot leaf ( Podophyllum peltatum ). It covers the eastern United States beyond the Great Plains , but without the Florida Peninsula . It stretches north along the Atlantic coast, where it extends into southwest Maine . From there, the northern limit of distribution runs through southern Ontario to the west bank of Lake Huron . The Great Lakes form the most north-westerly point of the species area, from here the limit of distribution of the shield-shaped foot leaf and Allodus podophylli runs almost steadily south to East Texas , where it meets the Gulf Coast . In the north the species area is bounded by the 20 ° C January isotherm ; the plant only lasts in regions with at least 150 frost-free days, starting in early May. The western limit of distribution is caused by the lower precipitation climate of the plains, while the warm winters of Florida are considered a limiting factor in the southeast.
A fungus find known as “ Puccinia podophylli ” on the Chinese barberry family Diphylleia sinensis raises the question of a wider distribution than the previously known one. However, since the corresponding material has not yet been investigated in more detail and there is a great geographical and related distance between the two host species, it remains questionable whether this is actually Allodus podophylli .
ecology
Allodus podophylli has a simplified so-called microcyclic life cycle compared to the development stages possible for rust fungi. The species does not have an asexual intermediate stage with uredia , but goes from aecia and spermogonia directly to telien formation. In addition, the species does not change host, but spends its entire development cycle on the shield-leaved foot leaf. The first spore beds, the spermogonia , are formed towards the end of spring, the Aecien follow soon thereafter. The fungus infects its host via the teliospores, which have overwintered last year and are stored on the ground from which the young plants sprout. The infection of the plant is not systemic, nor can the mycelium of the fungus overwinter in it. First of all, the leaf buds of the shield-leaved foot leaf, which appear first, are primarily affected. The teliospores form basidia relatively quickly and within a short period of time . Their sexual spores fall on the exposed parts of the plant and form a mycelium there, from which aecia and spermogonia develop. The spermogonia appear first, a short time afterwards the aecia. The first generation of Telia often forms at the same time and then comes from the flight of spores from already developed Aecia on other plants. From the aeciospores produced by the aeciae, the summer generation of the fungus also develops, which in turn consists of teliae. In contrast, there is only one generation of aecia and pycnia per year. The telia of the summer generation usually produce the teliospores from which the spring generation will germinate in the next year. Their thick walls protect them from the frosts of winter, while their long spikes prevent them from being washed into the earth when it rains. An unspecified fly species of the genus Mycodiplosis is a frequent predator of the fungus and feeds on its spore beds.
Systematics
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| Systematic position of the genus Allodus according to Minnis et al. (2012). It is a relatively original representative of the suborder Urediniae and is in this study as a sister clade to all other genera . |
The first description of the species comes from the year 1822. It appeared in Lewis David von Schweinitz ' Opus Magnum Synopsis fungorum Carolinae superioris on the fungal flora of North Carolina . Von Schweinitz described the fungus based on its aecia as Aecium podiophyllum , i.e. in the anamorphic genus of Puccinia . He mistakenly confused teliospores with aeciospores, which led Johann Heinrich Friedrich Link three years later to describe the same species again under the same name. However, according to the botanical nomenclature, the left description is not justified. Joseph Charles Arthur first placed the fungus in the genus Allodus in 1906. In a revision of the rust fungi, he introduced it as a form genus for those Puccinia species that have no uredia and no host change, have pigmented, two-celled teliospores and their spore beds together and under the Epidermis grow. For a few decades, however, he came to the conclusion that the development cycle was not a sufficient indicator of natural kin and rejected the genus Allodus again. Accordingly, the fungus was listed as Puccinia podophylli for the rest of the 20th century .
Molecular genetic studies of the rust fungi were the first to reveal the polyphyly of the genus Puccinia towards the beginning of the 21st century , albeit largely without drawing any consequences for the nomenclature. Andrew Minnis, Alistair McTaggart, Amy Rossman and Catherine Aime finally transferred the species back to the genus Allodus on the basis of a phylogenetic study, of which it is so far the only sure representative. They also established a neotype for the species. According to the DNA analysis, the genus is outside the Pucciniaceae and occupies a basal position in their broader family circle, the suborder Urediniae .
swell
literature
- Joseph Charles Arthur: A classification of the uredinees based on the structure and history of development . In: Results Scientifiques du Congrès International de Botanique Vienne 1905 . G. Fischer, Vienna 1906.
- DA Henk, DF Farr, MC Aime: Mycodiplosis (Diptera) Infestation of Rust Fungi is Frequent, Wide Spread and Possibly Host Specific . In: Fungal Ecology . tape 4 (4) , 2011, pp. 284–289 , doi : 10.1016 / j.funeco.2011.03.006 .
- Willem Meijer: Podophyllum peltatum - May Apple. A Potential New Cash-Crop Plant of Eastern North America . In: Economic Botany . tape 28 (1) , 1974, pp. 68-72 , doi : 10.1007 / BF02861382 .
- Andrew M. Minnis, Alistair R. McTaggart, Amy Y. Rossman, M. Catherine Aime: Taxonomy of Mayapple Rust: The Genus Allodus Resurrected . In: Mycologia . tape 104 (4) , 2012, p. 942-950 , doi : 10.3852 / 11-350 .
- Lewis David von Schweinitz: Synopsis fungorum Carolinae superioris . In: Writings of the Natural Research Society in Leipzig . tape 1 , 1822, p. 20-131 .
- HH Whetzel, HS Jackson, SB Mains: The Composite Life History of Puccinia podophylli Schw. In: Journal of Agricultural Research . tape 30 (1) , 1925, pp. 65-79 .
