Structural complexity and reproduction of rhodophytes 423
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Transcript of Structural complexity and reproduction of rhodophytes 423
GROUP 7GROUP MEMBERS
BS/2009/243BS/2009/244BS/2009/251BS/2009/252BS/2009/253BS/2009/254BS/2009/256BS/2009/257BS/2009/260
CONTENT
INTRODUCTIONCLASSIFICATIONSTRUCTURAL COMPLEXISITYREPRODUCTION
INTRODUCTION 680 generas 4000-6000 species Habitats:-
• In marine• In tropical• In warm water• In cooler regions• In fresh water
Eukaryotic
Nutrition mode• Autotrophic
Cell organizationUnicellular - CyanidiumMulticellular - Polysiphonia , Laurencia , Geledium
• Thalliopenly branching filamentsFleshy and foliose erect thalliEncrusting thalli (calcarious forms )
thallus
Crystal structure of Cyanidium
Geledium
CLASSIFICATION
KINGDOM- PROTISTA
DIVISION-RHODOPHYTA
CLASS-RHODOPHYCEAE
ORDER ORDER ORDER ORDER ORDER Nemalionales Cereniales Gelediales Cryptonemales Gigantinales
GENUS GENUS GENUS GENUS GENUSBatrachospermum Polysiphonia Geledium Jania Gracillaria
STRUCTURE
Cell wall• Rigid
• Inner componentCelluloseAnother polysaccharide
•Outer mucilaginous layerSulfated polymer of galactose – agar or carrageenan
•Some deposit calcium carbonate - family –
Corallinaceae (Coralline algae)
Cell structure
Absence of flagella and centrioles
Floridean starch as a storage product
Chloroplast• unstacked plastids in thylakoids•PigmentChlorophyll a,phycoerithrin,phycocyanin allophycocyaninpresence of the phycobilin or phycoerithin
STRUCTURAL COMPLEXISITY OF Gracillaria
From of thalli•Often fleshy thalli•Cylindrical or terete•Compressed or flattened•Foliose
Branching•Alternate•Di or trichotomous•Secund•Irregular
Constriction of branches • frequently Gracilaria shows a constriction at the point where a lateral branch joins a main axis.
Branch apex•Attenuate•Rostrate•Tapering•Apiculate•Obtuse•Blunt
Types of spermatangial conceptacles•Chorda type-superficial•Textorii type-shallow cavity•Verrucose type-deep pot like cavity•Polycavernosa type-compound verrucosa type
Characteristics of cystocarps•Form•Basal constriction•With or without rostum
Anatomy of cystocarp•Pericarp•Gonimoblast cells•Carposporangia•Absorbing filament
Types of cystocarps
Order – Nemalionales
Filamentous or uniaxial multicellularStem like thalli often dichotomously branched and gelatinous in texture
Batrachospermum
Order – Cereniales
SlenderFilamentous or uniaxial bush like plantsMore complex reproductive structure is characteristic of this order
Polysiphonia
Order- Gelediales
Thalli is cylindrical and wiry or flattened Usually pinnately branched Usually pseudo-parenchymatous
Order - Cryptonemales
Plants formDichotomously branched structureGrowing in tangledSmall clumpsBranches composed of rigidCylindrical segments with flexible joints
Order- Gigantinales
Crustose to fruticoseFoliose types with thin, broad fronds fruticose types with flattened Usually dichotomously branched Often fleshy thalliTissues as in cryptonemiales
REPRODUCTION OF
RHODOPHYTA
REPRODUCTION
SEXUAL REPRODUCTION ASEXUAL REPRODUCTION
ASEXUAL REPRODUCTION
Discharging Spores – monosporesIf condition are suitable monospores may attach to a substrate. By mitosis they produce new seaweeds.
Sexual reproductionWidely among the multicellular red algae.Alternation of generation.
Life Cycle of Polysiphonia
Isomorphic
Gametophytes:-•heterothallic•male gametophytes•female gametophytes
Spermatia:-•unite with the tricohogyne
spermatangia
Zygote:-•oogamous•auxillary cell become zygote•grows in a carposporophyte
Carpospores:-•type of mitospores•produce by carposporophyte•settle out of water column•grow in to tetrasporophyte
carcosporangia
Tetrasporsphytes:-•Isomorphic to gametophyte•Produce tetrasporangia in which meiosis takes place
Tetraspores:-•produce by meiosis•shed to the water•settle out of the water column•grow up in to gametophytes
Tetrasporangia
Sexual Reproduction ofPolysiphonia
REPRODUCTON OF Gracillaria
Isomorphic generation Gamitophyte
• Male-spermatangia• Female-carpogonia• Fertilization structure-cystocarp
Cystocarp•Carposporangia-carpospores
Germinate to tetrasporophytesFormation of tetrasporangium-tetrasporesGerminate to new thalli
Sexual Reproduction ofGracillaria
Order-Nemalionales
Mostly haplonticUsually no auxiliary cellsNurse cells perform similar functionNurse cells and auxiliary cells form prior to fertilization
Sexual Reproduction ofBatrachospermum
Order-Gigantinales
Three phase diplohaplonticA vegetative cell serves as auxiliary cellDeveloping prior to fertilizationSecondary pit often elongated in to an ooblast
Order-Gelediales
Three phase diplohaploticNo auxiliary cells
Gellidium
Life Cycle of Gellidium
Order-Cryptonemales
Three phase-DiplohaplonticAuxiliary cell in special filament growing from a vegetative cellSecondary pits elongated to an ooblast forming prior to fertilization
Order-cerenialesSlenderFilamentous or unisexual bush like plants lacking clear cut differentiation of cortex and medulla tissuesSimpler anatomy accompanied by more complex reproductive structure is characteristic of this order
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