Acts redundantly with HSP70-6 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. Down-regulated during seed maturation. Up-regulated during germination. By heat shock. Defective in protein import into chloroplasts during early developmental stages. May be due to an intron retention. Belongs to the heat shock protein 70 (TC 1.A.33) family. DnaK subfamily.