Elementary plant Biochemistry and Biotechnology (2+1)

Heat therapy & Chemotherapy

Heat therapy

• In plant tissue cultures viruses can also be eliminated with use of higher temperatures (heat treatment.).In such case explants are exposed to the incidence of higher temperatures, which are not lethal for plant cells, but they are lethal for viruses. Temperature range most commonly used in this therapy is 50-52oC with exposition about 10-30 minutes. In case this method is applied on whole plants, lower temperatures have to be used (32-40oC) with exposition about 4 - 30 days (depends on plant species and virus type).
  


• Mostly combination of thermo-therapy and meristem culture is used for virus-free plants production (e.g., cassava, bananas, citruses, strawberry, Irish potato, apples, chrysanthemas, garlic). Heat therapy combined with meristem tip culture is able to eradicate viruses, bacteria, and fungi but does not remove viroids. Unlike viruses, viroids are RNA without a protein coat – thus they are known as ‘naked’ RNA and are very difficult to eradicate. Usually the infected plant must be destroyed.

Chemotherapy

• Virus-free plants can be also obtained when antivirus compounds are added into nutrient solution (Ribavirin or 2-thiouracil).