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What is a Seed? We will learn more details later to answer this question. For now: 1.Seed Coat: a surface tissue to keep seed dry inside 2.Storage Tissue:

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Presentation on theme: "What is a Seed? We will learn more details later to answer this question. For now: 1.Seed Coat: a surface tissue to keep seed dry inside 2.Storage Tissue:"— Presentation transcript:

1 What is a Seed? We will learn more details later to answer this question. For now: 1.Seed Coat: a surface tissue to keep seed dry inside 2.Storage Tissue: could be a separate tissue (endosperm = inside seed) or part of the embryo (often cotyledons) 3.Dormant Embryo: a small diploid plant with minimal metabolism (suspended animation)

2 Capsella Seed: Seed Coat Endosperm Embryo Shoot Apex Cotyledons - dicot Hypocotyl Radicle Root Apex Micropyle

3 Seed Germination: Emergence of Radicle through Seed Coat WaterWarm Temperature So if you want to store seeds what are the conditions?Dry Cold Dormant seeds need more than moisture and warmth: Thick Seed Coat Thin Seed Coat Insufficient Development Inhibitor: Abscisic Acid Inhibitor: Phenolics Scarification Light Soil Fungus Association Stratification > Vernalization Leaching by Repeated Rain Kentucky Coffee Tree Lettuce Orchids Most CT feral plants Cacti Dark or Pea Dormancy is caused by:Is overcome by:Example: Seeds lacking dormancy need: nick digest scrub fire freeze-thaw cycles 6 weeks at 4° C 20° C

4 translation transcription hydrolysis Fruit + Seed Coat Aleurone Layer Barley Seed Germination Endosperm Storage Protein Amino Acids hydrolysis starch sugar -amylase RNA DNA GA imbibition water radicle apex shoot apex growth cotyledon monocot maltose Embryo exocytosis

5 hydrolysis translation transcription Lettuce Seed 660 nm 730 nm dark Seed Coat starch sugar -amylase RNA DNA imbibition water radicle apex shoot apex growth dicot photoreversibility Pfr Pr photoactivation Embryo phytochrome red and white light stimulate germination cotyledons Germination


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