Entorrhizomycetes

Some tiny things live in plant roots.

They make bumps on the roots. These bumps can be round or long. New bumps are light in color. Old bumps turn brown.

These tiny things live in wet dirt. They move through the water in the soil. They grow on plants like rushes and sedges. When the plant dies, the tiny things are let go. It is neat to learn about them.

Entorrhizomycetes is a small group of fungi. These fungi live as parasites on plant roots.

They live on plants called rushes and sedges. They make growths on the roots called galls. These galls can be round or long. New galls are pale. Old galls turn brown.

Inside the plant, the fungus grows thin threads. We call these threads mycelium. The fungus makes tiny spores called teliospores. These spores are released when the host plant dies. Scientists think the spores move through wet soil. They may spread using soil moisture. This group is very old. It may be 560 million years old. Some fungi in this group infect different plants. This might happen when they move to a new host. Many of these fungi might still be a mystery. Some may not even make galls on their hosts.

Entorrhizomycetes is a small group of fungi. They are part of a larger group called Dikarya. These fungi are parasites that live on plant roots. They mostly infect plants in the rush and sedge families.

They create growths on these roots called galls. These galls can be round or long shapes. New galls are often a pale color. As they get older, they turn brown. These growths are made of plant cells and fungal threads.

The way these fungi work is quite interesting. First, the fungal threads grow between the plant cells. Then, they grow inside the cells in coils. These coils turn into round cells called teliospores. These spores are released when the host plant dies. Scientists think the spores move through wet soil. This is because galls are more common in waterlogged soil. The spores help the fungus spread to new plants through moisture.

Scientists have studied these fungi to learn their history. A study in 2015 used a five-gene analysis. This study helped group them more clearly. They found these fungi are close to the Basidiomycota group. This group includes many common mushrooms. Before 2015, they were placed in a different subdivision. Now, we know they are a special class. This helps us understand how they relate to other living things.

There are three main groups, or genera, in this class. One group is called Entorrhiza. It infects sedge plants and has ridged spores. Another group is Juncorrhiza. It infects rush plants and has bumpy spores. The third group is Talbotiomyces. It is different because it infects Caryophyllales plants.

These groups split apart millions of years ago. For example, Entorrhiza and Juncorrhiza split about 42 million years ago. This was during the Oligocene and Miocene epochs.

This group of fungi is very ancient. Their history may go back 560 million years. That is to the late Neoproterozoic era. Even though they are old, we have not found many species. Some may have died out during mass extinctions. Others might still be a mystery to us. We might not see them because they do not always make galls. They might live on plants without showing any signs above the ground.

Entorrhizomycetes is a unique class of fungi within the phylum Entorrhizomycota. These organisms belong to the larger subkingdom Dikarya, which also includes the Basidiomycota and Ascomycota. They are known as obligate parasites, meaning they must live on a host to survive. Specifically, they target the roots of certain plants. They often form galls, which are abnormal growths, on the roots of plants in the Juncaceae (rush) and Cyperaceae (sedge) families.

The way these fungi grow is a complex biological process. It begins with the mycelium, which is a network of fungal threads called hyphae. These hyphae first grow intercellularly, which means they move between the cells of the host plant. Eventually, the hyphae grow inside the plant cells, forming coiled structures. These coils end in round cells known as teliospores. These spores are released when the host plant dies and the galls begin to disintegrate. Scientists believe these fungi might spread through soil moisture. This is because galls appear more frequently in waterlogged soils than in well-drained soils.

These fungi produce distinct structures called sori, which appear as galls on the roots. The galls can be globoid, irregular, or elongated in shape. They are made of a mix of fungal mycelium, parenchymatous cells, and vascular bundles from the plant. The color of these galls changes as they age. Younger segments of the galls are typically pale in color. As the segments get older, they turn brown.

Scientists categorize this class into three distinct genera. The first is Entorrhiza, which infects plants in the Cyperaceae family. Its teliospores are identified by having longitudinally ridged or cerebriform ornamentation. The second genus is Juncorrhiza, which infects the Juncaceae family. Its spores are different because they have verrucose-tuberculate ornamentation. The third genus is Talbotiomyces. This genus is unique because it infects plants in the Caryophyllales order. Talbotiomyces is also distinguished by its hyphal septa, which are simple pores that lack caps or membranes. In contrast, other members of the Entorrhizales order have dolipores that lack caps or membranes.

The history of these fungi is revealed through molecular phylogeny. A 2015 study used a comprehensive five-gene analysis to study Entorrhiza. This research suggested that Entorrhizomycetes might be a sister group to the rest of Dikarya or to the Basidiomycota. This is supported by shared traits, such as dikaryotic vegetative mycelium and fibrillate cell walls. The estimated age of the Entorrhizomycota stem is approximately 560 million years old. This places their origins in the late Neoproterozoic era. The divergence between the Talbotiomycetales and Entorrhizales happened about 50 million years ago. Furthermore, Entorrhiza and Juncorrhiza diverged approximately 42 million years ago.

During the Oligocene and Miocene epochs, both Entorrhiza and Juncorrhiza underwent a major radiation. This means they expanded into many new species and areas. Researchers have noted that the timing of these fungal changes does not perfectly match the evolution of their host plants. This suggests that host-shift speciation likely occurred. This means the fungi moved to new types of plants rather than evolving alongside them. Despite their ancient history, the number of known species is relatively low. Some scientists think many lineages went extinct during past mass extinction events. Others suggest that much of the diversity remains undiscovered. Because the host plants show no symptoms above the ground, some species might exist without forming visible galls.

Understanding Entorrhizomycetes helps scientists learn about the evolution of fungi. Some researchers speculate that the teliospore tetrad represents an ancestral state for Dikarya. A tetrad is a group of four cells. In these fungi, teliospores germinate into tetrads through internal septation. Each compartment in the tetrad produces hyphae that end in sigmoid propagules. This process is similar to how basidiomycete cells function. Studying these connections helps scientists map how fungi transitioned from water-dispersal to air-dispersal over millions of years.