Xanthophyceae

This ppt has been made by Xanthophyceae also known as yellow green algae. It occupies second position in algae classification by F.E Fritsch. It is classified into four orders. It contain xanthophyll in large amount that gives it yellow colour, hence it is commonly know as yellow green algae.

1. XANTHOPHYCEAE MADE BY – ANJALI KUMARI NIHARIKA I M.Sc. PLANT BIOLOGY & PLANT BIOTECHNOLOGY Bumilleria sp.

2. CHLORO XANTHOPHYCEAE DINO CHRYSO BACILLARIO CRYPTO CHLOROMONODINEAE RHODO PHAEO EUGLENO CYANO

3. TOPICS Introduction Classification Characteristic features Occurrence Thallus organization Cell structure Pigment Food storage Reproduction Economic importance Evolutionary perspective Example – Vaucheria

4. INTRODUCTION Tribophyceae , after the common genus Tribonema . Yellow green algae. Related to Phaeophyceae Photosynthetic organisms Genera – 118, Species - 600 Freshwater, marine waters, damp soil, or on tree trunks. DID YOU KNOW ??   Xanthophyceae are "secondary endosymbionts" -- they evolved from protists that engulfed algae and assimilated their chloroplasts

5. GENERAL CHARACTERS Occurrence : Mostly freshwater and a few marine representative Pigments : Chlorophyll , carotene and xanthophylls Pyrenoids : Usually absent Reserve food material : Chrysolaminarin , Oil and fat Cell wall : Rich in pectic compounds and composed of two equal pieces overlapping at the edges. Structure : Eukaryotic unicellular motile to simple filamentous Flagella : Present, two unequal , situated anteriorly. Longer one tinsel and shorter one whiplash Reproduction : Vegetative , Asexual and Sexual (Mainly Isogamous, Anisogamy is rare, Oogamous in Vaucheria)

6. CLASSIFICATION Fritsch (1935) recognizes the following orders in the class Xanthophyceae : Order Heterochloridales Suborder Heterochlorineae Family Heterochloridaceae (e.g.,  Heterochloris ) Suborder Heterocapsineae Family Heterocapsaceae (e.g.,  Chlorogloea ) Suborder Heterodendrineae Family Mischococcaceae (e.g.,  Mischococcus ) Suborder Heterorhizidineae Family Heterorhizidaceae (e.g.,  Rhizolekane ) Mischococcus

7. CLASSIFICATION Order Heterococcales Family Halosphaeraceae (e.g.,  Halosphaera ) Family Myxochloridaceae (e.g.,  Myxochloris ) Family Chlorobotrydaceae (e.g.,  Chlorobotrys ) Family Chlorotheciaceae (e.g.,  Chlorothecium ) Family Ophiocytiaceae (e.g.,  Ophiocytium ) Order Heterotrichales Family Tribonemataceae (e.g.,  Tribonema ) Family Heterocloniaceae (e.g.,  Heterodendron ) Order Heterosiphonales Family Botrydiaceae (e.g.,  Botrydium ) Botrydium Ophiocytium Tribonema

8. OCCURENCE

9. RANGE OF THALLUS STRUCTURE Thallus structure includes motile, palmelloid , dendroids , filamentous and siphoneous form. The following are levels of organisation which can be found in Xanthophyceae : Unicellular flagellate ( monadoid ) - Chloromeson Amoeboid - Rhizochloris , Myxochloris Palmelloid - Gloechloris Coccoid - Chloridella , Botrydiopsis , Characiopsis , Ophiocytium Filamentous - Tribonema , Hetrodendron Siphonous - Botrydium , Vaucheria . They lack pseudo-parenchymatous or truly parenchymatous thalli.

10. THALLUS ORGANIZATION Chloromeson Tribonema Myxochloris Botridiopsis Botrydium Vaucheria

11. CELL STRUCTURE The yellow green algal group is also known as the heterokonate because there are two structurally different flagella (or sometimes one flagellum) . Motile cells have a forwardly directed tinsel flagellum and a posteriorly directed whiplash flagellum . The cell wall is composed of pectic substances and sometimes silica . The cellulose as a cell constituent of the cell wall is meager but the cell wall in Botrydium is wholly of cellulose. The cell wall has tightly overlapping halves . In Tribonema , the cell wall is composed of ‘H’ shaped pieces which overlap each other alternately . The number of chromatophores in a cell, depending upon the species, varies from one to several .

12. CELL STRUCTURE Chromatophores usually lack pyrenoids but if present, are naked and these do not serve for the storage of food. Yellow green algae has uniform , simple shape of the chloroplast , usually discoid and parietal in position. The members of Xanthophyceae are both uninucleate and multinucleate . The eyespot in motile cells is always in the chloroplast and the chloroplasts are surrounded by two membranes of chloroplast endoplasmic reticulum . The outer membrane of the chloroplast-endoplasmic reticulum complex is usually continuous with the outer membrane of the nucleus. Mostly walls of non-motile cells are composed of two overlapping halves . The thylakoids are grouped into bands of three .

13. CELL STRUCTURE Xanthonema

14. PYRENOID PIGMENTS CHLOROPHYLL a, e, c CAROTENE ,  XANTHOPHYLL diadinoxanthin (major), lutein, violaxanthin, neoxanthin, flavacin , flavxanthin . CHLOROPHYLL - b

15. LIPID OIL FAT  -1,3 LINKED GLUCAN STARCH FOOD RESERVE

16. MODE OF REPRODUCTION

17. VEGETATIVE REPRODUCTION For majority of xanthophyceae only vegetative reproduction is known which occurs by; Vegetative cell division Algal cells divide mitotically to form 2 daughter cell ,eventually grows into an independent organism. Filament fragmentation Thallus often breaks into small fragment, each fragment grow independently to form new thallus. - mechanical pressure -dissolution of cell wall -difference in turgor pressure between adjoining cells. Vaucheria VEGETATIVE FILAMENT FROM ROCK

18. VEGETATIVE CELL DIVISION FILAMENT FRAGMENTATION Botrydium Tribonema aequale Pascher

19. ASEXUAL REPRODUCTION Xanthophycean organisms multiply asexually by zoospores , and aplanospores . Zoospores: motile naked structures with flagella. Zoospores are formed by a majority of the genera. The zoospores are biflagellate , with the forward tinsel flagellum usually being four to six times longer than the shorter whiplash flagellum .

20. Aplanospores : non motile spores , each cell may form a single aplanospore or its protoplast may divide to form many aplanospores. Akinetes : Vegetative cell develop into thick walled spore like structure with abundant food reserve . Always have additional wall layers around the protoplast which are fused with parent wall. They are resistant to unfavourable environmental condition.

21. ZOOSPORES APLANOSPORE AKINETES : Vaucheria

22. SEXUAL REPRODUCTION Sexual reproduction is very rare. Isogamy is common. Isogamy : two gametes fuse to form zygote , they are morphologically & physiologically similar. Anisogamy :takes place between morphologically & physiologically different gametes. Isogamy & anisogamy – Botrydium . Oogamy : advanced type , large non motile egg fuses with small motile sperm ,egg is formed within oogonium and sperm within antheridium. Isogamy & oogamy – Vaucheria

23. ISOGAMY - BOTRYDIUM ISOGAMY AND OOGAMY - VAUCHERIA

24. (a, b) Vaucheria borealis (a) oogonium, (b) antheridium and oogonium, scale bar 40 μ m (c–e) V. geminata ( V aucher ) DC .: (c) generative branch with central antheridium and two oogonia, scale bar 40 μ m (d) generative branch with central antheridium, scale bar 40 μ m, (e) generative branch with central antheridium and two oogonia, scale bar 25 μ m; (f) V. woroniniana generative branch with central antheridium and two oogonia , scale bar 40 μ m. 

25. ECONOMIC IMPORTANCE 1. Contaminent of water : Xanthophyta are important contaminants of source of water or drinking water supplies. These are able to change the quality of water but these are so small that mostly scientists ignore their role which they play for water. 2. Treatment plants : Some species of xanthopyta are presumably in response to elevate nutrients from fertilizers. Some species produce substantial biomass in wastewater treatment suggests they may have promise for nutrients or heavy metal removal.

26. 3. Water supply : • Health pertaining to algae in domestic water supplies have historically been focused on taxa known produce toxins, taste and odour problems. • PCR method developed for detecting marine may prove useful in future studies of water supplies. 4. Toxin production : • Freshwater xanthophyta algae are not known to be toxin producers, but marine species produce potent ichtyotoxins that lead to massive fish kill during blooms .

27. 5. Stabilization process of excess mud : Useful in the stabilization process of excess mud. E.g. Vaucheria 6. Production of oxygen : Due to its high content in chlorophyll and β-carotene, it is highly useful in the production of oxygen. 7. As food : Countries like Japan are consuming some forms of this algae. E.g. Vaucheria 8. For recreational uses : Vaucheria gives parrot green colour to gardens.

28. ECONOMIC IMPORTANCE Food Harmful effect Stabilization of mud Recreational uses Biofertilizer

29. EVOLUTIONARY PERSPECTIVE I. One line may have developed from an unicellular motile ancestry giving rise to non-motile unicells which may be solitary or colonial . II. Another tendency is to produce a tubular , or siphonaceous form. III. While the third one is leading to the formation of multicellular filamentous type.

30. Vaucheria • One example of a relatively common Xanthophyta is the class Vaucheria that gathers approximately 70 species • whose structure consists of several tubular filaments , sharing its nuclei and chloroplasts without septa • They live mainly in freshwater , although some species are found in seawater spreading along the bottom like a carpet.

31. Life cycle of Vaucheria Rhizoids & reproductive structures

32. CONCLUSION

33. CONCLUSION OF REPRODUCTION

34. REFERENCES SITES www.sciencedirect.com www.bioligyonline.com www.britannica.com www.plantscience4u.com BOOKS Dinabandhu Sahoo(2016), The algae world, Volume – 26, Xanthophyceae, Euglenophyceae and Dinophyceae (259- 267), Springer publication. Robert Edward lee: phycology page no 416 , Cambridge University press

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