Dr A Shinyguruce Assistant Professor Department of Microbiology amp CLT Dr Umayal Ramanathan College for Women Karaikudi Department of Micro biology amp CLTURCW Taxonomical Classification ID: 1044975
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1. Topic: PolysiphoniaBy, Dr. A. Shinyguruce, Assistant Professor, Department of Microbiology & CLT, Dr. Umayal Ramanathan College for Women KaraikudiDepartment of Micro biology & CLT,URCW
2. Taxonomical ClassificationClass : RhodophyceaeSub class : FlorideaeOrder : CeramialesFamily : RhodomelaceaeGenes : PolysiphoniaDepartment of Micro biology & CLT,URCW
3. OccurrenceRed algae. All species are marine.World wide distribution. 900 species.Attached to rocks & stones.Polysiphonia violacea is an epiphyte which grows on large brown algae.P.urceolata is saprophyteP.elongata is a lithophyteShore of Tuticorin & in RameswaramIndian species:-P.fastigata P.platycarpaP.variegata P. elongataDepartment of Micro biology & CLT,URCW
4. Department of Micro biology & CLT,URCW
5. Thallus structureTriphasic plant 3 phasesHaploid gametophyteDiploid carposporophyteDiploid tetrasporophyteGametophyte & tetrasporophyte are similar and independent.Carposporophyte is attached to gametophyte.Beautiful feather like appearance. Grows upto 5-35cms height.In thallus – erect system, creeping system & rhizoids.Made up of branched filaments- serve as perennation.Department of Micro biology & CLT,URCW
6. Rhizoids:Vertically downward from creeping system.Hold fast – helps to attach thallus to the substratum.Erect system grows upward from creeping system.Made up of profusely branched filaments.Filaments – heterotrichous – 3 typesMain axisLong brachesShort branchesMain axis is polsiphonous or multiaxial – many parallel siphons (filaments)Central siphon or axial siphon surrounded by 4-20 pericentral siphonsDepartment of Micro biology & CLT,URCW
7. Long branches – unlimited growth and are similar to main axis.Short braches – trichoblasts. They are short & limited growth.Have only central siphons. Pericentral siphons are absent.MonosiphonousTrichoblasts are dichotomously branched, colourless (chromatophore absent)Some trichoblast bear sex organs – fertile trichoblastFertile branchesMale trichoblast – bears cluster of anthridiafemale trichoblast - carpogoniumDepartment of Micro biology & CLT,URCW
8. Department of Micro biology & CLT,URCW
9. Cell structureCentral siphon – large – axial cell or central cells.Pericentral siphon – smaller in size – pericentral cells.Cells interconnected by pit connection.Cell is bounded by cell wall – 2 layersOuter – pectin substanceInner – celluloseDepartment of Micro biology & CLT,URCW
10. Inside the cell wall – plasma membrane- surrounds the cytoplasm which enclose central vacuole.In cytoplasm – many discoid chromatophores.In chromatophores:- chlorophyll a & c. alpha & beta carotenes, xanthophylls, phycocyanin–R, and phycoerythrin-R.Reserve food – Floridean starch & floridosideDepartment of Micro biology & CLT,URCW
11. growthGrowth takes in the single apical cell at the tip of axis.Transverse division – from the central siphon.Then undergo periclinal division – form pericentral cells.Department of Micro biology & CLT,URCW
12. reproductionSexual and asexual reproductionGamethophyteCarposporophyteTetrasporophyteGametophyte – free living, haploid plants. GametesZygote – carposporophyte – diploid – asexually produce carpospores.Tetrasporophyte – independent – germination of carpospore – diploid plant – tetraspore – haploid –female & male gametophyte. Department of Micro biology & CLT,URCW