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Colour, smell and taste – the beautiful world of plants and chemistry Alison Foster, University of Oxford Botanic Garden Dubrovnik, Croatia, 2012.

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Presentation on theme: "Colour, smell and taste – the beautiful world of plants and chemistry Alison Foster, University of Oxford Botanic Garden Dubrovnik, Croatia, 2012."— Presentation transcript:

1 Colour, smell and taste – the beautiful world of plants and chemistry Alison Foster, University of Oxford Botanic Garden Dubrovnik, Croatia, 2012

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3 Plants and Chemistry Colour Smell Taste

4 Colour Main pigment types –Porphyrins (nitrogen containing) –Flavonoids (incl. anthocyanins) –Carotenoids (terpenes) –Betalains (nitrogen containing)

5 Colour β-carotene cyanidin-3- glucoside betanidin

6 Colour Anthocyanins: Found in many plant families – except those in Caryophyllales Found in all plant tissues 10 9 tonnes produced per year in nature 2% of all carbon fixed via photosynthesis is converted to anthocyanins

7 Ferns (and Fern allies) Gymnosperms Angiosperms

8 Colour Functions of anthocyanins: Pollinator attractant Sunscreen – succulents and autumn leaf colouration Anti-feedants – bitter tasting

9 Colour Anthocyanins as pollinator attractant? Bromeliaceae

10 Colour Anthocyanins as sunscreen or antifeedant or both?

11 Colour Anthocyanins as antifeedant ?

12 Colour Metasequoia glyptostroboides dawn redwood Rhodoxanthin:

13 Colour Daucus carrota carrot beta-carotene

14 Colour Solanum lycopersicon tomato lycopene:

15 Colour Betalains: Amino-acid derived Nitrogen containing – metabolically more expensive Yellow to red pigments (betaxanthins and betacyanins) Only present in plants in order Caryophyllales

16 Caryophyllales

17 Colour Betalains: Caryophyllales: Beetroot (Amaranthaceae) Bougainvillea (Nyctaginaceae) Pokeweed (Phytolaccaceae) Carnations (Caryophyllaceae)

18 Smell Nicotiana attenuata from the SW United States –Releases benzyl acetone when flower opens at night –Attracts hawkmoth pollinators Pollinators are also herbivores (larval stage) Upon herbivore attack, flowers no longer produce benzyl acetone nor open at night Day opening flowers are then hummingbird pollinated

19 Smell Lavandula angustifolia camphorcineole linalyl acetate linalool

20 Smell Amorphophallus titanum Spadix emits smell of rotting flesh Pollinators are attracted –Carrion-eating beetles –Flesh flies Smell made up of amines and disulfides putrescine cadaverine

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22 Smell Cercidiphyllum japonicum –Senescing and abscising leaves –Green leaves contain maltol glucosides –Yellow brown/fallen leaves contain maltol

23 Taste Chilli peppers (Capsicum species) contain capsaicin “Hotness” measured on the Scoville scale Test method devised in 1912 by Wilbur Scoville Now measured by HPLC

24 Taste 0 Jalapeño pepper Scotch Bonnet 5, ,000 Naga jolokia1,040,000 Sweet pepper Chilli pepper Scoville Heat Units

25 Taste Euphorbia resiniferatoxin Resiniferatoxin 16 Billion SHU

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27 Taste Ginger – Zingiber officinalis, Zingiberaceae Active constituent of fresh ginger is gingerol Cooking ginger transforms it into zingerone

28 Taste Ginger – Zingiber officinalis, Zingiberaceae Dried ginger contains more of another molecule, shogaol The Japanese name for ginger is shōga

29 Taste Ginger – Zingiber officinalis, Zingiberaceae Dried ginger contains more of another molecule, shogaol The Japanese name for ginger is shōga

30 Taste Vanilla– Vanilla planifolia, Orchidaceae

31 Taste

32 caffeine theophylline theobromine

33 Taste theobrominecaffeinetheophylline

34 Conclusions


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