Chapter 29- Fungi

Fungi that live in close association with plant roots are said to be mycorrhizal
The fungi along with the roots they are associated with are referred to as mycorrhizae
==Fungi are critical to the productivity of forests, croplands, and rangelands.==
Fungi that make their living by digesting dead plant material are called saprophytes.
Note that there are two basic components of the carbon cycle on land:
- The fixation of carbon by land plants-meaning that carbon in atmospheric C02 is reduced to form sugar, which is then used to synthesize cellulose, lignin, and other complex organic compounds in the bodies of plants.
- The release of C02 from nearly all organisms as the result of cellular respiration-meaning the oxidation of glucose and production of the ATP that sustains life

Only two growth forms occur among fungi:
- single celled forms called yeasts
- multicellular, filamentous structures called mycelia
The filaments making up a mycelium are called hyphae
In most terrestrial fungi, each filament is divided into cells by cross-walls called septa
Some fungal lineages have hyphae that are coenocytic meaning that they are not divided into separate cells
Fungi produce reproductive cells called spores by sexual or asexual reproduction that are resistant to drying
Most fungal species that undergo sexual reproduction produce one of four types of distinctive reproductive structures:
- Swimming gametes and spores
- Zygosporangia- Cells from yoked hyphae fuse to form a distinctive spore-producing structure called a zygosporangium
- Basidia- Mushrooms, brackets, and puffballs form specialized club-shaped cells at the ends of hyphae called basidia
- Asci- Cups, morels, and some other types of fungi form specialized sac-like cells called asci
Conidia can be dispersed by water or wind currents and grow into new hyphae when conditions are right.
Fungicides are substances at can kill fungi or slow their growth

Fungi and land plants often have a symbiotic (“together-living”) relationship
Scientists categorize these symbiotic relationships as:
- mutualistic if they benefit both species
- parasitic if one species benefits at the other’s expense
- commensal if one species benefits while the other is unaffected.
The name αrbuscular (“little-tree”) was inspired by the bushy, highly branched hyphae that form between the cell walls and the plasma membrane of root cells.
AMF are also called endomycorrhizal fungi, because they grow inside root cell walls.
Endophytes (“inside-plants”) are organisms that live between and within plant cells.
Extracellular digestion is a digestion that takes place outside the organism.
When genetically distinct nuclei from the two different mating types exist within a single mycelium, it is considered heterokaryotic
Dikaryotic (“two-kernel”) occurs when their cells are divided by septa, and each cell contains two nuclei, one from each mating type.
The fusion of nuclei is called karyogamy

Yeasts reproduce when daughter cells pinch off from the parent cell after mitosis. This asexual reproductive process is called budding.
==Fungi are a large and diverse group of organisms. They are economically important, and they also play important roles in the environment.==