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How are basidiomycota characterized?
- -by basidiospores (meiospores) formed on basidia(singular= basidium)the site of meiosis
- - septate hyphae- some have clamp connections
- - most of life cycle spent as dikaryon (n+n)
- - no specialized gametangia- plasmogamy via fusion of hyphae
What are In the order of Pucciniales?
Describe rust fungi?
- -Most species are heterothallic
- -simple septal spores
- -are obligate biotrophs
- -have intercellular hyphae with haustoria
- -have complex life cycles with up to five distinct spore types
- -some species require two hosts for completion of life cycle = heteroecious
- -some species complete life cycle on one host = autoecious
WHat are the types of Pucciniales life cycles?
- - macrocyclic - all five spore stages are present
- - demicyclic - uredinial state (II) is absent
- - microcyclic- aecial (I) and uredinial (II) state are absent
What is stage 0 in rust fungi life cycle?
- - results from infection by a haploid basidiospore
- -haploid state (n)
- - small pyncidial structures often in clusters
- -develop in 4-6 days in herbaceous tissue up to 3-4 years in conifer wood
- -receptive hyphae arise from upper walls and protrude through opening (ostiole)
- -spermatia is a small one celled hyaline incapable of germination
- -spermatia is a sweet sticky exudate which attracts insects
- -dikaryotization occurs when spermatium fuses with receptive hyphae; nucleus moves down intercellular hyphae in host to aecial initials
What is stage I in rust fungi life cycle?
- - formed on same host as spermagonia
- -dikaryotization in aecial initials ( n+n)
- -aeciospores are one celled and form in chains usually pale orange in mass
- -chains of aeciospores usually surrounded by aecial peridium
- -aeciospores cannot infect the same host on which they are produced in heteroecious rusts
- -infection by aeciospores results in uredinia (or telia in demicyclic rusts)
What is stage II in rust fungi life cycle?
- -repeating state: urediniospores are able to re-infect host on which they are formed and can cause secondary cycles of infection
- -formed in uredinia on leaves stems fruits fronds sub-epidermal becoming erumpent
- -urediniospores usually one celled echinulate (small spines) are round to Ovoid with germ piers formed on stalk
What is stage III in rust fungi life cycle?
- - teliospores form in the uredinium (if present)
- -teliospores are site of karyogamy (n+n)
- -teliospores germinate by formation of basidium and basidiospores
- -teliospores have a dormancy requirement in most species
- - teliospores provide basis for taxonomy of rust fungi
What is stage IV in rust fungi life cycle?
- -diploid nucleus migrates into developing basidium and undergo meiosis
- -septa formed in response to meiotic divisions (=four celled basidium)
- -each cell of basidium forms a sterigmata and basidiospores are forcibly discharged
- -basidiospores germinate from germ tubes orient growth using physical cues from the plant surface
- -differentiate into appressoria when in contact with stomata indirect penetration of wheat leaves
Describe Ustilaginomycotina smuts
- - mostly biotrophs
- -have unique septa morphology
- -parasitic dikaryotic phase and a saprotrophic haploid phase
- -formed singly or in spore balls are mostly globose pigmented with thick ornamented walls
- -size are from 3.5-60 um in diameter
- -resistant structures
What are sorus?
- -they are teliospores formed in sori
- -composed of host and fungal tissue
- -Formed in host ovaries stems leaves or roots depending on the smut taxon