BackgroundRice 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.MethodsWe 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.ResultsAs 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.ConclusionsThe 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-015-0328-y) contains supplementary material, which is available to authorized users.

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Two novel negative-sense, single-stranded (ss) RNA viruses were identified in watermelon plants and named watermelon crinkle leaf-associated virus 1 and 2 (WCLaV-1 and -2), respectively. The multipartite genomes consist of three RNA molecules of ~6.8, 1.4, and 1.3 kb. The genomes and the deduced proteins of RNA1 and RNA3 show features resembling those of members in the genus Phlebovirus and Tenuivirus; however, the predicted proteins encoded by RNA2 are related to the movement protein (MP) in the genus Ophiovirus and Emaravirus. Furthermore, these two viruses define a novel clade in the family Phenuiviridae, order Bunyavirales, which is phylogenetically related to the viruses in the above four genera. Moreover, after mechanical inoculation with WCLaV-1 seedlings of the natural host watermelon plants develop crinkling similar to those observed in the field. These findings enhance our understanding of the evolution and the classification of ssRNA viruses.