Overexpression of rice black-streaked dwarf virus p7-1 in Arabidopsis results in male sterility due to non-dehiscent anthers.

Feng Sun,Yijun Zhou,Qiufang Xu,Tong Zhou,Yongjian Fan,Xia Yuan

doi:10.1371/journal.pone.0079514

Abstract

Rice black-streaked dwarf virus (RBSDV), a member of the genus Fijivirus in the family Reoviridae, is propagatively transmitted by the small brown planthopper (Laodelphax striatellus Fallén). RBSDV causes rice black-streaked dwarf and maize rough dwarf diseases, which lead to severe yield losses in crops in China. Although several RBSDV proteins have been studied in detail, the functions of the nonstructural protein P7-1 are still largely unknown. To investigate the role of the P7-1 protein in virus pathogenicity, transgenic Arabidopsis thaliana plants were generated in which the P7-1 gene was expressed under the control of the 35S promoter. The RBSDV P7-1-transgenic Arabidopsis plants (named P7-1-OE) were male sterility. Flowers and pollen from P7-1-transgenic plants were of normal size and shape, and anthers developed to the normal size but failed to dehisce. The non-dehiscent anthers observed in P7-1-OE were attributed to decreased lignin content in the anthers. Furthermore, the reactive oxygen species levels were quite low in the transgenic plants compared with the wild type. These results indicate that ectopic expression of the RBSDV P7-1 protein in A. thaliana causes male sterility, possibly through the disruption of the lignin biosynthesis and H2O2-dependent polymerization pathways.

Highlights

Rice black-streaked dwarf virus (RBSDV), a member of the genus Fijivirus in the family Reoviridae, causes rice black-streaked dwarf and maize rough dwarf diseases, which lead to severe yield losses in crops in China, Japan, Korea, and other Asian countries [1,2,3]
A great deal of effort has been made to elucidate the interactions between the virus, insect vectors, and host and environmental conditions, few RBSDV proteins involved in pathogenesis have been identified, and the biochemical basis of disease symptom development remains largely unknown
Our results suggest that RBSDV P7-1 is a novel determinant of disease symptom development

Summary

Introduction

Rice black-streaked dwarf virus (RBSDV), a member of the genus Fijivirus in the family Reoviridae, causes rice black-streaked dwarf and maize rough dwarf diseases, which lead to severe yield losses in crops in China, Japan, Korea, and other Asian countries [1,2,3]. S1 encodes a putative 169-kDa RNA-dependent RNA polymerase, while S2 and S4 encode a major core structural protein and the outer shell B-spike protein, respectively [6,7,8]. Western blotting analysis of viral particles has suggested that the minor core capsid protein and major outer capsid protein are encoded by S8 and S10, respectively [8,10,11]. Immunoelectron microscopy has revealed that S9 ORF1 P9-1 is a nonstructural protein that accumulates in the intracellular viroplasms in infected plants and insects [8]. The protein encoded by S6 is a viral RNA silencing suppressor and has an intrinsic ability to interact with P9-1 [13,14,15]

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