Cloning and characterization of a thaumatin-like protein gene PeTLP in Populus deltoides × P . euramericana cv. ‘Nanlin895’

Thaumatin-like protein (TLP) genes constitute a large, highly complex gene family involved in host defense against abiotic stresses, as well as other physiological processes. However, their functions in the abiotic stress-induced defense response in poplar remain largely unknown. In this study, one full-length cDNA from a hybrid poplar ( Populus deltoides × P . euramericana cv. ‘Nanlin895’) that encodes a TLP was isolated by RACE and designated PeTLP . The deduced amino acid sequence of PeTLP encodes a protein of a predicted molecular mass 24.5 kDa and a p I of 8.19. Transcript of PeTLP accumulated in stems, but the gene showed low transcriptional levels in roots and leaves. PeTLP was upregulated in leaves after abiotic treatments, including 200 mM NaCl, 10 % PEG6000, 100 μM gibberellin, 1 mM salicylic acid and 100 μM abscisic acid. Subcellular localization analysis showed that GFP-tagged PeTLP predominantly localizes as discrete points in the cytoplasm and the periphery of the plasma membrane. Recombinant PeTLP obtained using Escherichia coli expression produced antifungal activities to Rhizopus sp., Aspergillus niger and Penicillium citrinum . These results suggest that PeTLP is an abiotic stresses-induced protein and plays roles in physiological processes of poplar development, and is involved in the defense of poplar against abiotic stresses. Manipulation of PeTLP in poplar or other trees should improve their performance under various abiotic stress conditions.