Fungus (plural fungi) are a group of heterotrophic eukaryotic organisms such as yeast, molds, and mushrooms that get food from decaying materials and other living organisms. Fungi are classified as a separate kingdom from other eukaryotic kingdoms i.e Plantae, Animalia, and Protozoa. Fungi possess the substance chitin in their cell wall which differentiates them from plants, bacteria, and some protists.
Fungi are heterotrophic eukaryotes as they don’t have chlorophyll to synthesize their food. They absorb their food from other living things, and decaying materials by secreting enzymes. Fungi are the basic decomposers in the ecological ecosystem. Moreover, the study of fungi is known as Mycology. Mycology is the branch of Biology specifically Botany. Well, you can learn Morphology, Classification, Features, Life Cycle, and Functions of Fungus in this post.
Occurrence
Fungus is abundantly found worldwide because of their very small size, and their cryptic life cycles in soil or on dead materials. Fungi also live in the form of symbionts of plants, animals, and also parasites. The fungus may be noticeable during fruiting, either as mushrooms or as molds. Fungi have an essential role in the decomposition of organic matter by maintaining nutrient cycling in the environment. The fungus kingdom has a tremendous diversity of taxa with numerous ecologies, life cycle processes, and morphologies.
Fungus diversity ranges from unicellular marine chytrids to enormous mushrooms. However, only very little biodiversity of Kingdom Fungi is known yet which has been estimated at 2.2 million to 3.8 million species. And only about 148,000 species of Fungi have been characterized yet. Briefly stating the facts, over 8,000 species of estimated fungus are known to be harmful to plants and 300 can be pathogenic to humans. Since the 18th and 19th-century, Carl Linnaeus, Christiaan Hendrik Persoon, and Elias Magnus Fries have classified fungi taxonomically according to their shape & structure (e.g., characteristics such as spore color or microscopic features) or physiology.
Morphology of Fungus
Fungi produce hyphae which are cylindrical, thread-like structures 2–10 µm in diameter and up to several centimeters in the expanse. Fungi grow by tips (apices) of hyphae. New hyphae are typically produced by the synthesis of new cues at existing hyphae by a procedure named branching. Sometimes hyphal forks are grown which gives rise to two parallel-growing hyphae. Hyphae may also fuse by a process called hyphal fusion (or anastomosis). So, hyphal fusion leads to the development of a mycelium, an interconnected system of hyphae. Hyphae may be of two types:
- Septate hyphae
- Coenocytic hyphae
Septate hyphae are divided into compartments by cross walls (internal walls, called septa). Each compartment/ septa contains one or more nuclei. Coenocytic hyphae are not compartmentalized such as in the phylum of Basidiomycota. Coenocytic hyphae contain multinucleate supercells.
Characteristics
Fungi are eukaryotic heterotrophic organisms that possess characteristics linked to both animals and plants. Fungi contain true nuclei (membrane-bound nuclei chromosomes). The fungus also possesses ribosomes of 80s type. Here are some of the characteristics of Fungi that are different from other organisms or similar to them.
Similar Features
- Like all other eukaryotes, fungi contain membranous nuclei that possess DNA with coding and non-coding regions.
- Fungi also contain membrane-bound cytoplasmic organelles like mitochondria etc.
- Like animals, fungi lack chlorophyll and need energy sources to perform their basic metabolic functions.
- Like plants, fungi have cell walls and vacuoles. And both of them can reproduce by sexual and asexual patterns.
- Fungi grow as tubular, expanded, and thread-like (filamentous) patterns called hyphae. Hyphae contain numerous nuclei and thrive by their growing tips.
- There are some single-celled fungi (yeast) that don’t produce hyphae. While some of them form both hyphal and yeast phases.
- More than 70 fungal species display bioluminescence.
Unique Features
- Some species of Fungi like unicellular yeasts can reproduce by budding or fission.
- Dimorphic fungi can transit between the two yeast phase and hyphal phase in reaction to environmental situations.
- Fungi produce many secondary metabolites that are similar to those produced by plants.
- The fungal cell wall is composed of chitin and glucans. It’s worth noting that chitin is present in plants’ cell walls while glucan is in arthropods’ exoskeleton.
- Abundant fungi lack an efficient system (vascular bundles) for the transport of nutrients & water such as the xylem and phloem in many plants.
- In place of the vascular system, some fungi, such as Armillaria, produce rhizomorphs, which perform functions similar to the roots of plants.
Also, visit Common Plant Diseases- An Overview of Plant Pathology
