Stramenopiles (Heterokontophyta)

• autotrophs – from diatoms to brown algae... – (chlorophylls a + c1 c2 c3)

• heterotrophs, parasites

• chrysolaminaran and oil, starch is not produced !!!

• usually 2 flagella, 2 rows of tubular mastigonemata (from glycoproteins, production in ER) – tripartite structure (basal part, tubular part, hairs)

Stramenopiles (Heterokontophyta)

Chrysophyceae

- Ochromonas

BR – basal part

TS – tubular part

LE – hairs

Stramenopiles - flagella

functionally differentiated

flagella - heterokont

longer anterior flagellum,

pleuronematic – with

mastigonemata

shorter posterior, usually

smooth, often reduced,

associated with stigma

• 4 membranes, thylakoides stacked in triplets, girdle lamella

nuclear membrane

2layered plastid membrane

nucleus

pyrenoid chrysolaminaran vacuole

plastid ER

girdle lamella

lamella (triplets)

oil globules

Stramenopiles - plastids

• plastids: chl a + c1 c2 c3 in different combinations

β-carotene, fukoxanthin (brown colour)

vaucheriaxanthin (Xanthophyceae, Eustigmatophycae)

Stramenopiles - plastids

• originally 3 classes (Cavalier-Smith) - Heterokontophyta:

– Chrysophyceae

– Bacillariophyceae

– Phaeophyceae

– thereafter additionall autotrophic groups aded

• David J. Patterson – Stramenopiles

– mastigonemata, tubular crists in mitochondria, open mitosis

– heterotrophic groups included

Stramenopiles - classification

Ochrophyta:

• Chrysophyceae (zlativky)

• Dictyochophyceae (dictyochy)

• Phaeothamniophyceae

• Pelagophyceae

• Bolidophyceae

• Phaeophyceae (chaluhy)

• Xanthophyceae (různobrvky)

• Eustigmatophyceae

• Bacillariophyceae (rozsivky)

• Raphidophyceae (chloromonády)

• .....

heterotrophs:

• Pseudofungi

• Bicosoecida

• Labyrinthulomycetes

• Opalinata

• Blastocystis

Stramenopiles - classification

Chromista, Stramenopiles, Ochrophyta

Yang et al. 2012

Bolidophyceae

• marine flagellates

• picoplankton (1.2 mm)

• heterokont flagella

• sister group to diatoms

• established in 1999

Bolidophyceae

diatoms probably

evolved from flagellates

• picoplanktonic marine flagellates

Bolidophyceae

Bolidomonas

Parmales • nannoplanktonic, coccoid algae

• siliceous cell wall composed of oval or three-sided cell wall

(similar to diatoms)

• cold marine waters (Antarctida)

Parmales

Parmales

Dictyochophyceae

General characteristics • flagellates

• heterokont features (flagella, plastid)

• morphologically and ecologically diverse organisms

• Dictyochales – marine, skeleton-bearing species

• Pedinellales – freshwater

• Rhizochromulinales – marine

• Florenciellales – marine

Chang et al. 2012

Dictyochales

siliceous skeleton

nucleus

flagellum

pseudopodium

mucilaginous

envelope

• siliceous skeletons, microtubule-supported pseudopodia

Dictyocha – life cycle • production of naked flagellates without skeleton

Dictyocha – recent species

Dictyocha fibula Dictyocha speculum

Dictyocha – fosil species (silicoflagellates)

Naviculopsis

Dictyocha

• found in cold waters (determination of seawater temp.)

Pedinellales

• mixotrophic and heterotrophic species

• in freshwater and brackish waters

• rare

Pedinellales autotrophic

Pedinella

Apedinella Pseudopedinella

Pedinellales heterotrophic

Pteridomonas

Actinomonas

Pedinellales heterotrophic

Actinosphaerium Actinophrys

Rhizochromulinales

• autotrophic

• amoeboid cells with pseudopods

• marine (puddles in tidal zones)

Florenciellales • Florenciella • Pseudochatonella

Pelagophyceae

General characteristics

• class described in 1993

• marine organisms of various thalli types

• tiny flagellates, as well as large

seaweed-like organisms

• Pelagomonadales, Sarcinochrysidales

Pelagomonadales • picoplanktonic algae

• paraflagellar bar, reduced system of flagella roots

Pelagomonas – Pacific

Pelagococcus – free-living of symbiotic in foraminifera

Sarcinochrysidales • benthic, filamentous or thallose organisms

• sometimes very abundant, and considered as a pest

Sarcinochrysidales Chrysocystis (noodle-alga)

Sarcinochrysidales

Chrysophaeum

Yang et al. 2012

PX clade

• includes Phaeophyceae and Xanthophyceae

• presence of electron-opaque vesicles beneath the plasma

membrane (= physodes in Phaeophyceae) – probably

associated with the production of unique cell wall materials

Xanthophyceae

General characteristics

• ca 100 genera, 600 species

• mostly coccoid or filamentous

• phytoplankton of freshwater bodies

• soil algae

General characteristics

• majority of species rare, in a small number

Chloroplasts • yellow-green color

• chrysolaminaran as storage product

Flagellates

plastid ER

2layered plastid membrane

girdle lamella

lamella (triplets)

nuclear membrane

• subapical flagella, acronema in small flagellum

• stigma in chloroplast, photoreceptor photoreceptor

Cysts

• only in some species

• endogenous, impregnated by silica

Cell wall

• often composed by two pieces, impregnated by silica

Bumilleriopsis Tribonema

Reproduction

• asexual – vegetative division, zospores, aplanospores

• sexual – only Vaucheria

Evolutionary parallelism

Characiopsis

Chloridella

Bracteacoccus Botrydiopsis

Characium

Chlorella

Evolutionary parallelism

• chromatography, ultrastructure

Xanthophyceae Chlorophyceae

668 nm – chl a 668 nm

668 nm

668 nm

634 nm – chl c

634 nm 634 nm

Traditional classification

• 7 orders (Bailey & Anderson 1998)

Rhizochloridales

• amoeboid thallus, pseudopodia

• very rare

Myxochloris – multinuclear plasmodia in hyalocytes, Krkonoše Mts.

Mischococcales

• coccoid species, rigid CW (in some species in two pieces)

• metaphyton, soil, rarely in phytoplankton

Mischococcales Goniochloris – two-pieced CW, plankton

Mischococcales Characiopsis – epiphyte

Mischococcales Botrydiopsis – up to 60 mm in diameter

Mischococcales Borydiopsis – up to 60 mm in diameter

Mischococcales Bumilleriopsis

Mischococcales Ophiocytium – dendroidal, colony-like clusters

Mischococcales Mischococcus – dendroid colonies in submerged plants

Tribonematales • branched or simple filamentous thallus

Tribonematales Tribonema – frequently in clear, slightly acidic waters

Tribonematales Xanthonema – frequent soil alga

Tribonematales Bumilleria

Tribonematales Heterococcus – branched filaments, in soil

Tribonematales Heterococcus caespitosus – photobiont of lichen Verrucaria

Botrydiales Botrydium granulatum – multinuclear, siphonal thallus

• saclike vesicles+ rhizoids

• grows on damp soil

• zoospores, aplanospores

Vaucheriales Vaucheria – branched, coenocytic thallus; freshwater, brackish, soil

Vaucheriales Vaucheria – cell organisation

apical

zone

subapical

zone

vacuolized

zone

sporangium synzoospore

asexual

reproduction

sexual

reproduction antheridium

oogonium

spermatozoides

hypnozygote

Vaucheriales

Vaucheriales Asterosiphon – enigmatic macroscopic alga

Cambra-Sánchez, 2011

Phylogeny • cell wall organisation

Phylogeny

Chlorellidium

Botrydiopsis

Vaucheria

Tribonema

Maistro et al. 2009

• 4 major clades

• Botrydiopsis

pyrenoidosa is not a

Xanthophyte

• Pseudobumilleriopsis

as a separte genus

Pleurochloridella botrydiopsis

• differs from Xanthophytes by possessing fucoxanthin

Phaeothamniophyceae

Phaeothamnion – freshwater bodies, pools and ponds

• unbranched or branched filaments

• formally in Chrysophyceae

• class established in 1998

(analysis of molecular data)

Phaeothamniophyceae Stichogloea – mucilaginous colonies, in alpine lakes

• Aurearena cruciata – sandy beaches of Japan

• coccoid algae, flagella retained underneath the cell wall

Aurearenophyceae

Tetrasporopsis fuscescens

• cool and slow- or moderately fast-flowing water

• traditionally classified in Chrysophyceae

Chrysomerophyceae

Giraudyopsis

• marine benthic alga

Chrysomerophyceae

• branched filaments

• related to brown algae

Schizocladiophyceae

Stramenopiles age • radiation in Ordovician

• impact to the evolution/diversity of green algae?