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Tissue Culture

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Micrografting
Micropagation by micrografting results in offspring that are genetically identical to the parent plant. This is useful for replicating superior cultivars of fruit or flowering trees. Micrografting involves joining a piece of a mature tree (scion) to a seedling (rootstock). The scion will become the new trunk and branches of the tree and the rootstock will become the root system. The cambium is a key component in a successful graft as cambium layers from both the scion and the rootstock must be matched for a successful graft. The cambium is an active layer of cells located between the bark and woody portion of a stem or branch.  Applications of Micrografting techniques

1. Elimination of viruses
The in vitro micrografting technique has proved to be very useful in the regeneration of whole orchards of citrus fruits infected by viruses. This is because it is difficult to obtain rooting of the in vitro isolated apex in trees. However, grafting the apex onto a suitable rootstock would eliminate this problem. 2. Grafted plants bypass the juvenile stage that is associated with sexual seedlings. 3. Production of plants resistant to pest, diseases, cold, water stress, waterlogging, salinity and etc. For the shoot-tip micrografting technique, it is necessary to:

1. Obtain rootstock seed and germinate seedlings in vitro * Make sure the seeds used for rootstock production are not infected by any seed-borne pathogen. * Wrap groups of 10 peeled (shelled) seeds in a gauze. Disinfect the seeds in a laminar flow hood, immersing them in 10% sodium hypochlorite (commercial formulation) plus 1% Tween 20 for 10 minutes. Wash three times with sterile distilled water and, using aseptic techniques, plant two seeds in each sterile culture tubes containing the seed germination medium. Cover with kaputs. * Keep the tubes at 27 ºC in the dark, until the seedlings reach grafting size, approximately in 2-3 weeks. 2. Obtain young shoots

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