AsIB259 encodes a putative non-specific lipid transfer protein in Astragalus sinicus.AsIB259 protein was overexpressed in Escherichia coli Rosetta 2(DE3) and the kinetics of the recombinant protein binding to P-96 fluorescence probe was examined.Simultaneously,its capacity of binding to different fatty acids and fatty acid derivatives was measured as well.Furthermore,the symbiotic phenotype associated with AsIB259 overexpression was investigated.The results showed that AsIB259 displayed high binding activity toward fatty acids with 16-22 carbon chain length；and its overexpression in hairy roots led to an increase of 1.5-fold nodule number,but to a decrease of nitrogenase activity.The results indicated that AsIB259 may play an important role in nodulation and nitrogen fixation.