Identification and characterization of a small heat shock protein 17.9-CII gene from faba bean (Vicia faba L.)

We cloned and characterized the full-length coding sequence of a small heat shock protein 17.9 gene from faba bean encoding 160 amino acids and containing the conserved a-crystallin domain at the C-terminus. Homology and phylogenetic analysis suggested its proximity with the class II sHsp members of fabaceae family. Therefore, we name this gene as VfHsp17.9-CII. The VfHsp17.9-CII transcript showed a clear heat stress induction pattern in leaves of young seedlings and flowering plants. Transient expression of VfHsp17.9-CII fused with green fluorescent protein reporter indicated its nuclear localization. Overexpression of recombinant VfHsp17.9CII protein in Escherichia coli cells increased tolerance of the bacterial cells to heat and arsenic stresses. The reduction of faba bean pollen viability in response to heat stress correlated with the accumulation pattern of VfHsp17.9-CII transcript in heat stressed pollen. It is suggested that VfHsp17.9-CII protein plays a key role in heat and heavy metal stress tolerance.