IDENTIFICATION OF PROTEINS FROM CAMBIUM TISSUES OF THE CHINESE WHITE POPLAR (POPULUS TOMENTOSA) SAMPLED DURING THE GROWING SEASON

Abstract

Various protein extraction methods have been used to investigate Chinese white poplar (Populus tomentosa) proteomics. However, extracting and characterizing proteins from woody plants remains a challenge. Two-dimensional gel electrophoresis is a powerful, widely used method for the analysis of complex protein mixtures extracted from biological samples. The technique separates mixtures of proteins along two dimensions, by isoelectric point and molecular weight, and can resolve thousands of different proteins. Here, we report a new application of two-dimensional gel electrophoresis to investigate the proteomics of P. tomentosa cambium tissues over the course of a growing season. Of three protein extraction methods that we compared (the Tris-phenol method, trichloroacetic acid-acetone method, and trichloroacetic acid-acetonephenol method), trichloroacetic acid-acetone was the most efficient approach for protein extraction from cambium tissues of P. tomentosa. After extraction, the proteins were separated using two-dimensional gel electrophoresis. The protein quantities of six spots changed over the course of the growing season from February to July. Five spots were identified using matrixassisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry, and the sixth spot was identified by liquid chromatography–mass spectrometry. The proteins included enolase, class Ia chitinase, and four unnamed proteins. Our results show the best approach to proteomics in P. tomentosa and reveal trends in protein activities during a growing season in this tree species.