The structure of mycelial cords and rhizomorphs of fungi: A minireview

Abstract

Fungi are ubiquitousthey are found in any conceivable environment, i.e., both aquatic and terrestrial habitats. They remain one of the most diverse groups of organisms on Earth. Because fungi are heterotrophic, they obtain their nutrients by colonizing their substrates with a vegetative mass of hyphae called mycelium. These hyphae secrete enzymes that digest nutrients locked in colonized substrates, after which the nutrients are then absorbed by the hyphae. Not only do hyphae constitute the mycelium of fungi, but they also form other structuresmycelial strand, mycelial cords, and rhizomorphsthrough which fungi are able to spread in their environment in search of new substrates to colonize. The aim of this present paper is to explore the structure of mycelial cords and rhizomorphs. Rhizomorphs are among the most complex organs produced by fungi. They are root-like structures constituted by a series of differentiated tissues each with distinctive hyphal type, orientation, size, and function. Thus, rhizomorphs are produced as a result of a coordinated growth of millions of bundled hyphae. Rhizomorph-forming fungi thrive in nutrient-poor environment and are known to cause devastating destruction to homes and plantations. Because rhizomorphs serve as exploratory organs, and they enhance the survival of rhizomorph-forming fungi in plantations and homes, farmers, homeowners, attorneys, and even mycologists and plant pathologists, need to understand and appreciate their potential to wreak havoc that results in huge annual financial losses.

Syncytia in Fungi

“…Hyphae can also serve as building blocks for more complex or differentiated hyphal arrangements in basidiomycetes and some ascomycete species, called ‘rhizomorphs’ or ‘mycelial cords’. Rhizomorph is a term used for growing hyphal tips with apical dominance, and mycelial cords are aggregations of up to thousands of younger (and oftentimes melanized) parallel bundled hyphae that are fused by anastomosis to an older, leading hypha [ 53 , 54 , 55 ]. These rhizomorphs and mycelial cords are highly differentiated and share many structural components that resemble plant roots, such as a small region behind the growth front that undergoes rapid cell division and layers of cells that guard the growing cords against damage by soil particles [ 56 ].…”

Early Identification of Root Rot Disease by Using Hyperspectral Reflectance: The Case of Pathosystem Grapevine/Armillaria

“…Staude is a globally distributed and widely studied genus of pathogenic fungus belonging to the Basidiomycota class, Agaricales order, and Tricholomataceae family [1,2]. It spreads under the soil through root contact or complex structures named rhizomorphs, which can grow relatively fast for a hundred meters and penetrate the root bark of the hosts [3,4]. Armillaria spp.…”

Diversity and Phylogeny of Novel Cord-Forming Fungi from Borneo

“…We did not find any obvious cord morphology patterns distinct to certain taxa or clades (Figure 3). It is possible that the different cord morphologies observed such as thickness are related to growth substrate or the age/life cycle stage of the fungi as opposed to a fixed morphology for that taxon [55]. This would explain the morphological differences observed between the collected fungi despite close genetic relationships.…”