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How Does Life Work?

Symbiosis and Interliving:
Crossing the Kingdoms:
Fungi

Fungi and Plants Cross Kingdoms
to become Symbionts


Nutrition
FUNGI & TREE ROOTS

explored at length in

Plants New; Mycorrhiza Plus

Ectomycorrhiza on pine roots. The photo fails to show the micro-scopic hyphal rootlets that surround these coated roots

Nutrition
FUNGI & HERB ROOTS

explored at length in
Plants New; Mycorrhiza Plus

 

Arbuscular Mycorrhiza greatly expands the absorbtion ability of roots--more access to water and nutrients

Protection
FUNGI & PLANT LEAVES
: Go to:

Plants New: Fungal Symbiosis in Leaves

Spores of beneficial fungi called endophytes land on leaves and burrow in to live in spaces between leaf cells. From there they attack pathogenic (disease-causing) fungi that try to infect and eat the leaf. An estimated 40,000 fungal spores land on a tropical leaf every day, so most leaves contain fierce but microscopic battlegrounds.

 

 

 


protective endophyte fungi inside grass blade

Protection
Fungi and Herb Roots

An herb is a non-woody flowering plant. A forb is an herb that is not a grass. Predatory fungi that live in the root zone of forbs kill and eat tiny nematode worms that attack plants. Some symbiont fungi form constricting loops that lasoo the worm (see photo); other fungi use sticky traps to hold the worm.

Germination & Nutrition
Orchids and Fungi

Orchids comprise one-tenth of all flowering plants, some 25,000 species. Orchid seeds are tiny, without much nutrient. To germinate, orchid seeds must be already partnered with a fungus. In early growth, orchid seedlings have no chloroplasts and are totally dependent on their fungal symbiont for food. Later, when the orchid does become photo-synthetic, the symbiosis is clearly two-way, each partner supplying the other. But early in life, orchids are parasitic on a fungus, without another choice.

Fescue grasses and many other grasses live in symbiosis with the beneficial fungus genera Neotyphodium. The fungus lives inside the leaves and seeds of the grass. There it receives all the carbohydrate food it can use, and there it helps the grass three ways: it helps the plant grow more vigorously; it increases resistence to stresses such as drought and heat;to defend the plant from grazers, the fungus manufactures alkaloid compounds which attack the nervous systems of herbivores such as cattle and grasshoppers.

 

 

 

Tall Fescue


Neotyphodium hyphae in a grass blade

Relatives of Neotyphodium, the Epichloe fungi, are also symbionts of grasses. They confer similar benefits as Neotyphodium, and add another: they create odors that attract Botanophila pollinating flies, so they help their partners reproduce.

Fungi & Arthropod Animals
Cross Kingdoms to become Symbionts

 


Septobasidium fungus with scale insect colony inside

typical scale insect

Nutrition, Protection, Dispersal

"Velvet fungus" septobasidium hosts tiny scale insects inside its layered growth. It releases a chemical that attracts scale insects. Once they arrive, a symbiotic colony forms. On the bark, the insects pierce the tree for sap; the fungus grows into the insect and both feed on the sap. A layer of tunnels and galleries let young insects move about. The scale insects receive protection from winter, extreme weather, and from bird beaks. The fungus receives food and, as described below, gets dispersed (new places to thrive). The fungus does not enter all the scale insects. Some are free to mate and lay eggs. At hatching, the larvae crawl around and fungal spores cling to them. When they emerge as adults, they may stay in the home colony, or travel to another branch or even another tree and start a new symbiotic colony when the fungal spores germinate.

Reproduction, Nutrition and Shelter

Ambrosia Beetles are a guild of small beetles that "farm" ambrosia fungus inside dead trees and cut logs, that host a community of multiple symbionts that include include bacteria, yeasts, and ambrosia fungus. They are a co-evolved symbiotic community. Beetles carry fungal spores in deep pouches in their exoskeletons. The pouch edges are covered with bristles (setae) which help the beetle scrape fungal spores into their pouches. Adult beetles are tiny. You have probably seen their tiny perfect holes in dead wood. They bore into sapwood and excavate galleries in which they grow their fungus, which is their only food. When their eggs hatch in galleries, the larvae eat the fungus too.

Reproduction, Nutrition and Protection

The sirex wood wasp lives in symbiosis with a fungus that she injects into pine trees as she lays her eggs. She also injects a toxic mucus which kills cambium cells. When the fungus grows, it feeds on those dead cells. When the wasp larvae hatch, they feed on the fungus. A good mother.


Reproduction and Protection
mountain pine beetles
and blue stain fungus

These beetles carry blue stain fungus spores in pits near their mouthparts. When they chew into a pine, the spores quickly grow in the phloem cells, which die and cut off liquid flow, including sticky resins which would otherwise trap the beetles in the galleries they chew to lay their eggs. The tree dies within months.

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