A Time-Course Proteomic Analysis of Rice Triggered by Plant Activator BTH

Abstract

Benzothiadiazole (BTH) is an artificial inducer of systemic acquired resistance. Due to rice being an important food crop and model plant, we investigated its response to BTH using label-free proteomics technology coupled with bioinformatics. Protein expression levels were verified using the multi-reaction monitoring mode and semi-quantitative RT-PCR. BTH treatment can up- or down-regulate many proteins produced by the rice host at all four periods, with the numbers of proteins being 6/24, 9/10, 14/10, and 8/20, respectively. Compared with mock treatments (phosphate buffered saline with 0.1 % dimethylsulfoxide and 0.5 % Tween-20), some proteins related to plant resistance were only detected after BTH treatments, such as ascorbate peroxidase (POD) 3, chitinase A, thioredoxin-dependent POD 2, beta-1,3-glucanase 2, POD superfamily protein, major facilitator superfamily (MFS) protein, copper/zinc-superoxide dismutase (SOD) 1, pathogenesis-related protein (PR) 1. Other proteins showing up-regulation after BHT treatment included PR-5, glyceraldehyde-3-phosphate dehydrogenase C, plasma-membrane associated cation-binding protein 1, and oxidoreductase family proteins. These results indicated that BTH was involved with inducing rice resistance. Some up-regulated proteins were also involved in other metabolic processes. The activity and expression level of POD, phenylalanine ammonia-lyase (PAL), and SOD, lipoxygenase (LOX), beta-1,3-glucanases, and chitinases were determined using the enzyme activity assay and semi-quantitative RT-PCR. These results indicated that BTH can enhance the activity of beta-1,3-glucanases, LOX, PAL, and POD. BTH can also induce up-regulation of the copper/zinc-SOD, ascorbate POD, glutathione POD 1, Chitinase, and LOX1 genes.