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Reproduction and propagation
Seeds – the conventional process Vegetative propagation Tissue culture
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Scientific and Industrial Perspectives
Plant propagation Scientific and Industrial Perspectives
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Market Size (World Markets)
Seeds (hybrid and open pollination)- $ 37 B (10 top companies control 2/3 of the industry. Vegetatively propagated plants - $ 12 B Tissue culture propagules - $ 400 M Transgenic seeds and plants $ 7 B
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Industrial considerations
High quality of germplasm True to type Pathogen free Uniformity Good physiological condition Data sheet certification Seasonal production - storage Shipping and receiving - packaging, soil substrates, routing,indexing Intellectual property rights (IPR)
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International trade in plant material
Phyto-sanitary certification Import permit Shipping and receiving Standardization in quality control International agreements on “Variety Registration” breeders rights and IPR
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Easy to handle and ship to end user Manageable post harvest quality
Sexual propagation Genetic variation Pathogen “free” Inexpensive Easy to handle and ship to end user Manageable post harvest quality Long shelf life Possible to breed Germination technology Inbreeding Juvenility
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Vegetative propagation
Propagules carry clonal history Germplasm improvement – Lack of variation Phyto-sanitary problems Genetic fidelity High cost of production Uniformity Predetermined architecture Hardening requirements Handling difficulties Cuttings seeds
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Industrial aspects genetic constitution vs. quality true to type
Disease and virus free uniformity pysiological state certification (plant passport) shelf life timing packing intellectual property rights
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International trade in propagation material
Health certification Import/export documentation Packaging/ packing True to type IP issues UPOV Convention DUS
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Totipotency “The ability of each cell in a multicellular organism to develop into a complete individual” CELL THEORY [ Schleiden and Schwan, 1838] “Among the plants, any cell can be separated from the plant and continue to grow. Thus, entire plants may consist of cells whose capacity for independent life can be clearly demonstrated…
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Totipotency
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Apical Meristems Shoot apical meristem –
The majority of plant mass originates from SAM. All above ground portion. Give Rise to lateral tissue stractures Root meristem – Majority of bellow ground tissue No lateral structure (root cap only)
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MERISTEMS IN PLANTS Central Zone (CZ) – large cells, divide Less frequent than surrounding cells. Cells divide to replenish cells used to form leaf primordia. Peripheral Zone (PZ)- morphogenic zone Rapid cell division, the major source of meristem cells Rib Zone (RZ) – formation of tissues and the stem
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APICAL MERISTEM
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Cell division Tunica (L1) - Cells divide in anticlinal plane (perpendicular to the surface) Carpus (L2) – Periclinal cell division, (sectorial chimeras) Transition to primordium – periclinal division of the tunica Represent transition to primordium Founder cells – a predicted number of cells form leaves and flower parts
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Cell regulation in apical meristems
M. K. Barton, Twenty years on: The inner workings of the shoot apical meristem, a developmental dynamo. Developmental Biology 341 (2010) 95–113
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Axillary meristem formation
Plant form is regulated by the outgrowth of axillary meristem Axillary meristem occurs from the surface of leaf Primordia (in maize AM are not associated with the current leaf but with the margine of the previous leaf
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Apical meristem in Arabidopsis
מתוך M. K. Barton, Twenty years on: The inner workings of the shoot apical meristem, a developmental dynamo. Developmental Biology 341 (2010) 95–113
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Adventitious root meristems
Adventitious M. are formed from cambial tissue Most roots are formed from adventitious meristem . From the pericycle cell layer Adventitious buds form from displacement of axillary shoots or from true adv. initials
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ROOT MORPHOLOGY - INITIATION
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