Team:Cambridge-JIC/Marchantia

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<p>Let's leave the botanical jargon and head to the gardens:</p>
<p>Let's leave the botanical jargon and head to the gardens:</p>
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<h3> Intro to Byrophytes and how to get in their clang</h3>
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<h1> Marchantia, the new Chassis </h1>
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Primitive plants are everywhere and together are called Byrophytes. Byrophytes are divided into three lineages. In evolutionary order these are:
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<ul>
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<li>Marchantiaphyta or Liverworts (that's Poly!)</li>
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<li>then came Mosses (byrophyta)</li>
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<li>and finally the newer Hornworts or Anthocerotophyta.</li>
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<li>then came all the rest.</li>
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</ul>
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<h4>What makes Byrophytes special: Role-Reversal Plants and Nature's strange ways  </h4>
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Byrophytes are united by unique features. These include:
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<ul>
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<li>Sexual reproduction by spores - a fine line between bacteria, yeast and these plants</li>
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<li>No cumbersome flowers or energy absorbing seeds</li>
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<li>No lignin (what makes plants tough) or vascualture</li>
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and last but not least
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<li>a reversed life cycle!</li>
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</ul>
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<p> Byrophytes are indeed often referred to as 'Up-Side-Down' or 'Role-Reversal' plants. Their life cycle is the opposite of most: We and other organisms spend our life as diploids: two sets of chromosomes, one from Dad, one from Mother. We specialize a set of cells in our reproductive organs which undergo meiosis (splitting of cells to form 2 cells with 1 copy of each gene), forming a haploid egg or sperm. When the sperm and the egg come together, they form a haploid organism which grows. And the cycle starts again.</p>
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<p> Byrophytes live most of their life as haploids (only have one copy of their genes!). A set of cells differentiate to become the ova and the sperm. When the haploid sperm reaches the haploid ova, they fuse, become diploid for a short time, and then undergo meiosis (split genome) to form two haploid plants! Intrigued by this oddity? Go to 'Marchantia's Life Cycle' to find out more.</p>
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<p>But let's not underestimate them...</p>
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<h3>Close up on Mar-cam-tiophytes (liverworts) </h3>
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<p>Primitve does not mean frail; quite the contrary.</p>
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<h4> Looks, Location and Loveliness </h4>
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<p>Poly can be found found worldwide from tropical and arctic climates to your backyard! She likes moist soil or rocks in damp habitats. Her favourite hide-outs include banks of pools and rivers, bogs, fens and dune slacks.
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You can easily find her in man-made habitats such as gardens, paths and greenhouses. Some even dare calling her a horticultural weed! After fires, she rapidly colonizes the burnt ground, restoring an eco-stystem. </p>
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<h4>Morphology </h4>
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<p>Liverworts are wither of the leafy or thalose variety. Marchantia Polymorpha is a thallose one. Thallus means simply undifferentiated plant tissue. (not very descriptive)</p>
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<h4>The Dilemma: Food or Water?</h4>
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<p>Being thin, flat with a large surface area is great to maximise sunlight absorption and to photosynthesise lots; this comes at a cost: water evaporation. Plants that thrive have evolved to an optimum intermediate. Poly exhibits a beautiful simple morphological adaptation: air pores, the ancestors of the current stomata that most plants now have.</p>
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<h4>Rosette growth and Splash cups</h4>
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<p>Poly grows out in a rosette shape. If a thallus reaches the soil, it can become the start of a new plant. However this doesn't get her very far. At ___- weeks of development, a gemma cup appears at the centre of a thallus. The cup contains loose cells. As rain drops into the cup, the loose cells are propulsed out to find new ground to conquer. This allows simple rapid asexual isogenic reproduction</p>
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<h4>Reproductive Organs</h4>
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<p>Sexual reproduction, which allows gene mixing between two plants is another matter. Upon maturation at ___ weeks, the haploid Poly grows a reproductive stem at the centre. For the males, this is called a __ and resembles a flat disc on a stem. It bears the spores that will disperse. In females,an Umbrella appears.Underneath it is the protected Ova. With wind, rain or a researchers hand, the sperm is let loose and flies to collect under the sticky surface of the umbrella. Magic occurs: sperm and ova fuse. The diploid result undergoes recombination (gene mixing), divides multiple times and undergoes meiosis. The product is over ___ of haploid potential progeny with genomic diversity.<br>
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The reproductive organs can be stimulated to appear by exposure to infra-red light!
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</p>
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<h1> The new Mar-vellous Chassis </h1>
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<h3>OpenPlant</h3>
<h3>OpenPlant</h3>

Revision as of 16:45, 20 August 2014