Work shope on plant Cryopreservation

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                                                Name- Venkatesh Kolluru

Student number- 0803568

Course- MSc. BIOTECHNOLOGY

Module- BI1102A

Title of the work shop- PLANT CRYOPRESERVATION

Workshop tutor- Irene Tierney

                                         

AIM: To learn about the practical aspects of plant cryopreservation and its current developments in the field of plant biotechnology.

INTRODUCTION:

Cryopreservation is a process where the cells or the whole tissues are preserved by cooling the temperature to -196C (BP of liquid nitrogen). In these extreme conditions the biological activity even the biochemical reactions which would lead to cell death is effectively stopped. But this technique consists of problems like damage to the cell due to solution effect (used in the solution), dehydration and intra cellular ice formation. At this temperature the salts present in the cell may become crystal which can ultimately lead to fatal conditions. To overcome this problem vitrification solutions (sucrose, DMSO i.e. Di-Methyl sulphoxide, glycerol, etc.) are used. Vitrification solutions prevent the formation of ice crystals. They do it by lowering down the freezing point and increasing the viscosity. The time of exposure of cryoprotectants (i.e. vitrification solutions) is very important because the long exposure of chemicals towards the plant cells may result in to phytotoxicity. Cryopreservation is a technique which is carried out frequently for the conservation of plant genetic resources. This was initially developed by Withers and King in 1980, but the cryopreservation techniques which are used now a day have several modifications in the protocol which was used by the initial developers. The property of whole plant and plant tissue to regenerate from cryoreserved cells make this technique suitable for preserving and conserving plant genetic resources. This technique finds application in the vegetative propagation of many plants (which produce recalcitrant seeds i.e. which lose their viability at low freezing point) and crops like potato. Some species of plants survive during cryopreservation using a specific protocol but on the other hand some do not. The expected reason of non viability (after cryopreservation) associated with some plant could be due to the cellular heterogeneity, inadequate tissue culture regimes, genotype, and physiological differences.

Safety measures during cryopreservation:

There is certain safety measures associated with the use of liquid nitrogen. There is a risk of suffocation with the use of liquid nitrogen. To avoid this liquid nitrogen must be used in a proper ventilated room. The storage Dewar’s must be ventilated to prevent explosion. The skin and eye protection can be brought about by the use of the cold resistant gloves and safety glasses respectively.

Applications:

 The various applications of cryopreservation with respect to plant biotech are listed as:

  1. Storage of vegetative propagated crops
  2. Conservation of recalcitrant seeds bearing species
  3. Storage of transformed cultures
  4. Storage of tropical crops
  5. Storage of endangered species
  6. Storage of seeds
  7. Eradication of virus.
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The cryopreservation protocol contains the following stages:

  1. Culture selection:  The plant source selected must be of right growth stag, active and should be healthy. The selection could be a key factor in the success of cryopreservation.
  2. Pre- growth:  pre growth is the treatments which prolong the viability of cells during cryopreservation at freezing temperature. For this purpose various chemicals are utilised such as sugar, polyols, etc. which is usually osmotically active compounds, which act as dehydration factors. Some researchers have shown that compounds like ABA and trehelose that are produced by plants during stress have ...

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