Acts redundantly with HSP70-7 in the thermotolerance of germinating seeds. Plays an important role in the protein precursor import into chloroplasts. In cooperation with other chaperones, Hsp70s are key components that facilitate folding of de novo synthesized proteins, assist translocation of precursor proteins into organelles, and are responsible for degradation of damaged protein under stress conditions. Interacts with geminivirus movement protein (MP). Variegated cotyledons, malformed leaves, growth retardation and impaired root growth. Defective in protein import into chloroplasts during early developmental stages. Belongs to the heat shock protein 70 (TC 1.A.33) family. DnaK subfamily.