When chaperone harms
Increase of temperature above 40°C results in the synthesis of heat shock proteins (HSP70) not only in animals or microorganisms, but also in plants. These chaperones are involved in stabilizing and folding of nascent proteins, refolding of partly denatured proteins or directing unrepairable proteins for degradation, thus restoring cellular balance. HSP70 expression in plants is induced not only by higher temperature but also by almost every type of stressor associated with oxidative stress, such as salt, cold, drought, pathogens, ozone etc. However, in virus-infected plants, HSP70 can have both positive and negative effects because viruses usually recruit HSP70. HSP70 can promote the replication and translation of the viral genome, the formation of viral replication complexes, and the propagation of viral particles from cell to cell and throughout the plant. The review (https://doi.org/10.32615/bp.2021.001) is focused on how and under what circumstances plant HSP70 served as host factors helping the viruses. At the same time, the process of thermotherapy is known, when the plant can suppress a viral infection with a long-term elevated temperature (35-42 ° C, 4-6 weeks).
The following figure shows, which factors and conditions determine whether HSP70 will act as host factor accelerating virus replication and spread or as a defense compound.