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Page 1 Secretory Systems in Plants 1 Institute of Lifelong Learning, University of Delhi Discipline: Botany Subject: Plant Anatomy Lesson: Secretory Systems in Plants Lesson Developer: Dharmendra Kumar Mallick College/Department: Deshbandhu College, University of Delhi Lesson Reviewer: Prof. S.C. Bhatla, Department of Botany, University of Delhi Page 2 Secretory Systems in Plants 1 Institute of Lifelong Learning, University of Delhi Discipline: Botany Subject: Plant Anatomy Lesson: Secretory Systems in Plants Lesson Developer: Dharmendra Kumar Mallick College/Department: Deshbandhu College, University of Delhi Lesson Reviewer: Prof. S.C. Bhatla, Department of Botany, University of Delhi Secretory Systems in Plants 2 Institute of Lifelong Learning, University of Delhi Table of Contents Chapter: Secretory Systems in Plants ? Introduction ? Mechanism of Secretion ? Holocrine Secretion ? Merocrine Secretion ? Granulocrine Secretion ? Eccrine Secretion ? Classification of secretory structures ? External Secretory Structures ? Glandular Trichomes ? Hydathodes ? Salt glands and Chalk glands ? Glandular trichomes secreting lipophilic substances ? Nectaries ? Colleters ? Osmophores ? The glandular structures of carnivorous plants ? Internal Secretory Structures ? Internal secretory cells ? Types of internal Secretory Cells ? Crystals and Silica secreting cells ? Lithocysts ? Myrosin cells ? Oil cells ? Mucilage cells ? Tannin idioblasts ? Secretory cavities and ducts ? Schizogenous cavities Page 3 Secretory Systems in Plants 1 Institute of Lifelong Learning, University of Delhi Discipline: Botany Subject: Plant Anatomy Lesson: Secretory Systems in Plants Lesson Developer: Dharmendra Kumar Mallick College/Department: Deshbandhu College, University of Delhi Lesson Reviewer: Prof. S.C. Bhatla, Department of Botany, University of Delhi Secretory Systems in Plants 2 Institute of Lifelong Learning, University of Delhi Table of Contents Chapter: Secretory Systems in Plants ? Introduction ? Mechanism of Secretion ? Holocrine Secretion ? Merocrine Secretion ? Granulocrine Secretion ? Eccrine Secretion ? Classification of secretory structures ? External Secretory Structures ? Glandular Trichomes ? Hydathodes ? Salt glands and Chalk glands ? Glandular trichomes secreting lipophilic substances ? Nectaries ? Colleters ? Osmophores ? The glandular structures of carnivorous plants ? Internal Secretory Structures ? Internal secretory cells ? Types of internal Secretory Cells ? Crystals and Silica secreting cells ? Lithocysts ? Myrosin cells ? Oil cells ? Mucilage cells ? Tannin idioblasts ? Secretory cavities and ducts ? Schizogenous cavities Secretory Systems in Plants 3 Institute of Lifelong Learning, University of Delhi ? Resin ducts ? Lysigenous cavities ? Kino veins ? Schizolysigenous cavities and ducts ? Laticifers ? Economic importance of secretions ? Glossary ? References/ Further Reading ? Exercise/ Practice Page 4 Secretory Systems in Plants 1 Institute of Lifelong Learning, University of Delhi Discipline: Botany Subject: Plant Anatomy Lesson: Secretory Systems in Plants Lesson Developer: Dharmendra Kumar Mallick College/Department: Deshbandhu College, University of Delhi Lesson Reviewer: Prof. S.C. Bhatla, Department of Botany, University of Delhi Secretory Systems in Plants 2 Institute of Lifelong Learning, University of Delhi Table of Contents Chapter: Secretory Systems in Plants ? Introduction ? Mechanism of Secretion ? Holocrine Secretion ? Merocrine Secretion ? Granulocrine Secretion ? Eccrine Secretion ? Classification of secretory structures ? External Secretory Structures ? Glandular Trichomes ? Hydathodes ? Salt glands and Chalk glands ? Glandular trichomes secreting lipophilic substances ? Nectaries ? Colleters ? Osmophores ? The glandular structures of carnivorous plants ? Internal Secretory Structures ? Internal secretory cells ? Types of internal Secretory Cells ? Crystals and Silica secreting cells ? Lithocysts ? Myrosin cells ? Oil cells ? Mucilage cells ? Tannin idioblasts ? Secretory cavities and ducts ? Schizogenous cavities Secretory Systems in Plants 3 Institute of Lifelong Learning, University of Delhi ? Resin ducts ? Lysigenous cavities ? Kino veins ? Schizolysigenous cavities and ducts ? Laticifers ? Economic importance of secretions ? Glossary ? References/ Further Reading ? Exercise/ Practice Secretory Systems in Plants 4 Institute of Lifelong Learning, University of Delhi Introduction Unlike animals, it is difficult to distinguish secretion from excretion in plants. Secretion is defined as the elimination of substances which may still take part in metabolism whereas the excretion is the elimination of the end product of metabolism. Animals get rid of harmful and useless substances through their excretory system. The secretory system of animals is also well defined anatomically and physiologically. In plants, neither the structures involved in the release of substances nor the released substances can be easily categorized as secretory or excretory due to difficulty in ascertaining whether a substance is useful, harmful or superfluous for the plants releasing it. Therefore, only one term secretion is generally used to describe the various processes by which individual cells or multicellular structures perform any of the functions mentioned below. ? Remain alive and discharge their products outside the plant body or into special nonliving ducts or cavities within the plant body. ? Undergo lysis and rupture, releasing their contents, often into a duct. ? Store the product within the living cell or between protoplast and wall of the cell. Figure: Leaves of mangrove showing salt secretion on its surface. Source: http://www.mesa.edu.au/mangroves/mangroves02.asp Page 5 Secretory Systems in Plants 1 Institute of Lifelong Learning, University of Delhi Discipline: Botany Subject: Plant Anatomy Lesson: Secretory Systems in Plants Lesson Developer: Dharmendra Kumar Mallick College/Department: Deshbandhu College, University of Delhi Lesson Reviewer: Prof. S.C. Bhatla, Department of Botany, University of Delhi Secretory Systems in Plants 2 Institute of Lifelong Learning, University of Delhi Table of Contents Chapter: Secretory Systems in Plants ? Introduction ? Mechanism of Secretion ? Holocrine Secretion ? Merocrine Secretion ? Granulocrine Secretion ? Eccrine Secretion ? Classification of secretory structures ? External Secretory Structures ? Glandular Trichomes ? Hydathodes ? Salt glands and Chalk glands ? Glandular trichomes secreting lipophilic substances ? Nectaries ? Colleters ? Osmophores ? The glandular structures of carnivorous plants ? Internal Secretory Structures ? Internal secretory cells ? Types of internal Secretory Cells ? Crystals and Silica secreting cells ? Lithocysts ? Myrosin cells ? Oil cells ? Mucilage cells ? Tannin idioblasts ? Secretory cavities and ducts ? Schizogenous cavities Secretory Systems in Plants 3 Institute of Lifelong Learning, University of Delhi ? Resin ducts ? Lysigenous cavities ? Kino veins ? Schizolysigenous cavities and ducts ? Laticifers ? Economic importance of secretions ? Glossary ? References/ Further Reading ? Exercise/ Practice Secretory Systems in Plants 4 Institute of Lifelong Learning, University of Delhi Introduction Unlike animals, it is difficult to distinguish secretion from excretion in plants. Secretion is defined as the elimination of substances which may still take part in metabolism whereas the excretion is the elimination of the end product of metabolism. Animals get rid of harmful and useless substances through their excretory system. The secretory system of animals is also well defined anatomically and physiologically. In plants, neither the structures involved in the release of substances nor the released substances can be easily categorized as secretory or excretory due to difficulty in ascertaining whether a substance is useful, harmful or superfluous for the plants releasing it. Therefore, only one term secretion is generally used to describe the various processes by which individual cells or multicellular structures perform any of the functions mentioned below. ? Remain alive and discharge their products outside the plant body or into special nonliving ducts or cavities within the plant body. ? Undergo lysis and rupture, releasing their contents, often into a duct. ? Store the product within the living cell or between protoplast and wall of the cell. Figure: Leaves of mangrove showing salt secretion on its surface. Source: http://www.mesa.edu.au/mangroves/mangroves02.asp Secretory Systems in Plants 5 Institute of Lifelong Learning, University of Delhi The cells involved in secretion show the presence of dense protoplasts with other cellular components, the frequency of which is variable on the basis of the substance secreted. A common characteristic of mucilage secreting cells is the presence of abundant Golgi bodies. The mucilage is secreted by Golgi bodies and it is ejected from the protoplast by exocytosis. Figure: Electron micrograph of a maize root cap slime-secreting cell showing two Golgi stacks in the centre. These are surrounded by large white sacs filled with mucilage produced by the Golgi apparatus. Source: http://bscb.org/learning-resources/softcell-e-learning/golgi-apparatus/ The characteristic feature of cells secreting lipophilic substances is the presence of endoplasmic reticulum. The endoplasmic reticulum is spatially associated with plastids that contain osmiophilic substances. The endoplasmic reticulum and dictyosomes, which are the most important organelles for most types of secretion, are present in all plant cells. Therefore all plant cells are considered as secretory. Golgi apparatus Mucilage containing sacsRead More
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1. What are secretory systems in plants? |
2. How do secretory systems in plants contribute to biotechnology engineering? |
3. What are some examples of secretory products produced by plants using biotechnology engineering? |
4. How can plant secretory systems be manipulated for increased production of desired compounds? |
5. Are there any challenges associated with utilizing plant secretory systems in biotechnology engineering? |
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