Abstract
Differential proteomics is considered as one of the most powerful tools for evaluating relative expression of molecular moieties either in plants or animals. The present study focuses first on optimizing a rapid and sensitive protocol for the isolation of high quality protein to be used in two dimensional gel electrophoresis (2DE) from date palm samples, and then comparing differentially expressed peptides associated with red palm weevil (RPW) infestation of this plant using uninfested plants as control. Among the several methodologies we used for optimization, it was revealed that Phenol/ SDS extraction followed by methanolic ammonium acetate precipitation (designated as protocol 3 in this study) yielded high quality protein. Moreover, 2DE protein analysis demonstrated both qualitative and quantitative differences between control and infested date palm samples. Our differential proteomic methodologies showed 22 differential spots having modulation level = 1.5 fold. Subsequently, these differentially expressed peptides were subjected to MALDI-TOF peptide mass fingerprinting analysis for their characterization. The 11 peptides identified through these methodologies fall into three major functional groups including stress/ defense (5), photosynthesis (2), ion transport (1) related proteins and three with other functions. Our data revealed that proteins related to date palm defense or stress response were up-regulated in infested samples while the proteins involved in photosynthetic activities were down regulated. The present results indicated that RPW infestation of date palm plants induced molecular changes manifested through differential expression of proteins. Differentially expressed peptides besides increasing our understanding relevant to RPW infestation will help us in developing methodologies for early detection of RPW infestation beneficial for curbing this problem in economically important date palm trees.