| Summary: | 碩士 === 國立中興大學 === 生物科技學研究所 === 100 === Satellite RNAs (satRNAs) are subviral agents which depend on helper viruses and host factors for replication, encapsidation and movement. Bamboo mosaic virus (BaMV), a member of the genus Potexvirus, is the only potexvirus that naturally associates with a satRNA, designated satBaMV, which encodes a 20 kDa RNA-binding protein (P20) involved in efficient long-distance movement and replication of satBaMV. The aims of this study were to investigate the abilities of other non-cognate viruses in supporting the replication of satBaMV and to explore the effects of P20 phosphorylaion on the movement of satBaMV. Dimeric satBaMV transgenic plant lines expressing P20 fused with green fluorescent protein (GFP) either at N- or C- terminus were generated. BaMV and two non-cognate viruses, Potato virus X (PVX) and Foxtail mosaic virus (FoMV), were inoculated onto the transgenic plant to monitor their abilities in supporting satBaMV. Through the examination of GFP expressions in the inoculated transgenic plants, it was confirmed that the non-cognate helper FoMV marginally supports the replication of satBaMV, whereas PVX does not. Plasmids harboring GFP fused to the N- or C-terminus of P20 protein with mutations on the serine at amino acid position 11 (S11) to inhibit or mimic the phosphorylation state of P20 were constructed, and there cell-to-cell movement ability were examined in Chenopodium quinoa by fluorescent microscopy. The results revealed that both mutations of P20 reduced the cell-to-cell movement of satBaMV, corroborating the previous finding that phosphorylation of S11 is important for the expression and movement of satBaMV.
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