Slime Molds

Plasmodinaiophoromycota

Phylum of slime molds, includes endoparasitic slime molds

• trophic stage is INSIDE the host

• Obligate necrotrophic endoparasites of aquatic and terrestrial plants, algae, and chromista

• Cause host cells to hypertrophy or hyperplasia

• Leads to stunting of hosts

Myxomycota

Phylum of slime molds includes Dictyosteliomycetes and Myxomycetes

Dictyosteliomycetes

Cellular slime molds

• basic unit: uninucleate, no cell wall, haploid amoeba, and engulf bacteria

• no flagella in life cycle

• sexual reproduction of a macrocyst

• cell walls: made of cellelosic

• feed on microbes in soil, dung, decaying mushroom, plants

Myxomycetes

Plasmodial slime molds

• “true slime molds”

• in temperate forest’s most places like decaying logs, dungs or lawns

• feed on microbes mostly

• tool for morphogenesis

Slime mold

• Produce a trophic stage lacking a cell wall

• Food is phagocytized

• Feeding stages are amoebae or plasmodia

• no hyphae at any time in life

• no cell walls

Phagocytized

Engulf food and break it dow (like the blob)

Amoebae

uninucleate

Plasmodia

multinucleate

Plasmodiophora brassicae

club root of cabbage

Hypertrophy

Increase in cell size

Hyperplasia

Increase in cell number

Dictyosteliomycetes Characteristics

• Filose Psedopodia in amoeboid

• Microcysts: amoebae encystic is conditions are bad

• Community of individual cells keep in contact with secreted hormone

  • keep population steady and when density is enough, the amoebae stops feeding in aggregate streams

Dictyosteliomycetes Life Cycle

1. Food becomes scarce→ ameobae signal for aggregation ( release chem signal, cyclic AMP, that attracts nearby cells

2. Cells become sticky and adhere to each other to aggregate

3. Join together to form a Psuedoplasmodium (slug) that moves as a sling unit that is held togther my cell wall amterial and mucilaginous secretions

4. Slug travel to find good spot to reproduce with environmental cues

5. Culimination and becomes a sorocarp when conditions are good

Myxomycetes Life Cycle

1. Uninucleate cells: myxamoebae, swarm cells

2. Multinucleate somatic plasmodium

3. Reistant sclerotium stage

4. Spores

Swarm cells

Whiplash flagella with amoeboid contractions

Myxamoebae

• divide repeatedly give rise to a population, under harsh conditions it can form a microcyst

• eventually fuse in pairs and form a zygote

Plasmodium

• mass of protoplasm in thin membrane and gelatinous sheath

• gelatinous sheath with microfibrils shed as plasmodium creeps over surace

• fluid protoplasm makes net like streams

• nuclear divisions are simultaneous every 8 hours

• Gives rise to sporophores or sclerotia

Sclerotia

If conditions are bad the plasmodium changes

Sporophores

Become sporangium