Mycorrhizae

What are mycorrhizae ? The mycorrhizae are formed by a combination of mutualistic symbiosis between fungi and plant roots .

In many cases, the fungus and the plant become dependent on mycorrhizal associations and cannot develop on their own.

Plants can associate with more than one fungus at the same time, however, they usually have  specificity for  fungal partners, that is, each species of plant has certain species of fungi that best associate with it.

The fungi involved in this association are usually of the Zygomycetes class.

In mycorrhizal associations two entities involved are benefited fungi increase the surface ab s orção water and minerals d plant and and m contrast, provides plant nutrients from photosynthesis to the fungus.

Some plants are so dependent on mycorrhiza that they even need it to start their development. This is the case of orchids that, because they have very small seeds, have no reserves to start the germination process.

Most plants make mycorrhizal associations and the  increase in water absorption, allows them to adapt to drier climates and in less fertile soils.

Types of mycorrhiza

According to the morphological and anatomical aspect of fungi in relation to plants, we have two types of mycorrhizae that can occur alone or together in the same plant:

Types of mycorrhiza

·         Ectomycorrhizae

Fungal hyphae colonize only the intercellular spaces of the roots. They occur mainly in temperate tree species, very often in conifers that can be associated with more than 5,000 different fungi.

·         Endomycorrhizae

This is the most frequent type of mycorrhiza, more than 80% of the associations are endomycorrhiza.

Fungi penetrate the cells of the root system of vascular plants and  hyphae can form spirals, platoons, shrubs and vesicles. Fungi  multiply forming long absorption networks in the soil.

They can be of three types: arbuscular, ericoid and orchidoid.

The mycorrhiza form recesses inside the root cells, assuming a bush format. This shape increases the contact surface between the fungus and the cytoplasm of the plant cell.

The ericoid type has the growth of spiral hyphae in the superficial cells of plants and also outside the root. The hyphae perform an extracellular digestion called saprofitism, and remove from it organic matter that will be used by the fungus and the plant.

Already orquidoides mycorrhizae are specific to all orchids are dependent on fungi in the early development in at least one stage of its development.

Mycorrhizal fungi surround the seeds of orchids, penetrate their cells forming characteristic spirals and provide it with nutrients from other plants, guaranteeing germination and development until the cotyledon begins to make photosynthesis.

 

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