Comparative proteomic analysis of two rice cultivars (Oryza sativa L.) contrasting in brown planthopper (BPH) stress resistance

Abstract

The brown planthopper (BPH) is a pest which destroys rice paddy fields. To determine the molecular mechanism of the resistance of rice plants to BPH, the proteomic profiles of two contrasting rice cultivars, TN1 (susceptible) and PTB33 (resistant), were compared. This information was then used to investigate protein expression during BPH feeding. Rice seedlings were inoculated with BPH nymphs to screen for resistance behavior among five selected cultivars. Following inoculation, small BPHs were introduced to the rice seedlings at a ratio of 8:1 (BPH: rice seedling) and the hopperburn symptom on each cultivar was measured over the fourteen day period of observation. The samples demonstrating the highest resistance to BPH (PTB33) and susceptibility (TN1) were then chosen for protein extraction and comparison. An observed total of nineteen protein spots demonstrated significant differences between the two cultivars, with a two-dimensional electrophoresis (2-DE) and mass spectrometry (LC-MS/MS) approach adopted to identify the results of the experiment. The protein spots were then categorized into different groups according to the presence of a carbohydrate metabolism, antioxidants, protein synthesis, ATP synthesis, photosynthesis and stress response proteins. 2-Cys peroxiredoxin BAS1 (2-CysPrx-BAS1), putative inorganic pyrophosphatase (IPPase) and eukaryotic elongation factor 1 (EF-1) were reported to be 2.09, 2.25 and 2.22-fold up-regulated in resistant cultivar, respectively. It has also been shown that fructokinase (FK) and phosphoglyceratemutase (PGmutase) were only found using CBB staining in resistant cultivar, but not in susceptible cultivar. The protein up-regulation observed in the resistant cultivar might promote glycolysis and lignin biosynthesis via the phenylpropanoid pathway, which offers such plants protection against BPH infestation.