iTRAQ-based quantitative proteomics analysis of rice leaves infected by Rice stripe virus reveals several proteins involved in symptom formation

Rice plants infected by Rice stripe virus (RSV) usually leads to chlorosis and death of newly emerged leaves. However, the mechanism of RSV-induced these symptoms was not clear. We used an iTRAQ approach for a quantitative proteomics comparison of non-infected and infected rice leaves. RT-qPCR and Northern blot analyses were performed for assessing the transcription of candidate genes. As a whole, 681 (65.8% downregulated, 34.2% upregulated infected vs. non-infected) differentially accumulated proteins were identified. A bioinformatics analysis indicated that ten of these regulated proteins are involved in chlorophyll biosynthesis and three in cell death processes. Subsequent RT-qPCR results showed that downregulation of magnesium chelatase was due to reduced expression levels of the genes encoding subunits CHLI and CHLD, which resulted in chlorophyll reduction involved in leaf chlorosis. Three aspartic proteases expressed higher in RSV-infected leaves than those in the control leaves, which were also implicated in RSV-induced cell death. Northern blot analyses of CHLI and p0026h03.19 confirmed the RT-qPCR results. The magnesium chelatase and aspartic proteases may be associated with RSV-induced leaf chlorosis and cell death, respectively. The findings may yield new insights into mechanisms underlying rice stripe disease symptom formation.