Location: Floral and Nursery Plants ResearchTitle: Selective interaction between Chloroplast B ATPase and TGB1 retards severe symptoms caused by Alternanthera mosaic virus infection) Author
Submitted to: Plant Pathology Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/27/2014
Publication Date: 4/4/2014
Citation: Seo, E., Nam, J., Kim, H., Lakshman, D.K., Bae, H., Hammond, J., Lim, H. 2014. Selective interaction between Chloroplast B ATPase and TGB1 retards severe symptoms caused by Alternanthera mosaic virus infection. Plant Pathology Journal. 11736-11743. Interpretive Summary: Plant viruses cause significant disease losses in many crops; an understanding of the mechanisms of virus interactions with their hosts necessary for infection and systemic movement may lead to methods for interfering with the infection process, thus reducing losses to disease. The Triple Gene Block 1 (TGB1) protein of a potexvirus, Alternanthera mosaic virus (AltMV), is required by the virus for multiple functions, including cell-to-cell movement and suppression of RNA silencing (a means of overcoming innate host plant resistance mechanisms). Examination of the interactions between the TGB1 protein and host proteins demonstrated that the TGB1 protein interacts with several chloroplast proteins, with a differential response of one chloroplast protein to TGB1 variants from ‘mild’ and ‘severe’ isolates of AltMV. These interactions may be important for functions of TGB1 in both cell-to-cell movement of the virus, and in RNA silencing suppression, and in suppression of the basal defense responses of the plant, allowing more efficient viral invasion. This information will initially be of most interest to other scientists studying virus:host interactions and movement, and may eventually lead to development of methods to interfere with virus infection or systemic movement within infected plants.
Technical Abstract: The multifunctional triple gene block protein 1 (TGB1) of the Potexvirus Alternanthera mosaic virus (AltMV) has been reported to have silencing suppressor, cell-to-cell movement, and helicase functions. Yeast two hybrid screening using an Arabidopsis thaliana cDNA library with TGB1 as bait, and co-purification with TGB1 inclusion bodies identified several host proteins which interact with AltMV TGB1. Host protein interactions with TGB1 were confirmed by Bimolecular Fluorescence Complementation, which showed positive TGB1 interaction with mitochondrial ATP synthase delta' chain subunit (ATP synthase delta'), light harvesting chlorophyll-protein complex I subunit A4 (LHCA4), chlorophyll a/b binding protein 1 (LHB1B2), chloroplast-localized IscA-like protein (ATCPISCA), and chloroplast ß ATPase. However, chloroplast ß ATPase interacts only with TGB1L88, and not with weak silencing suppressor TGB1P88. This selective interaction indicates that chloroplast ß ATPase is not required for AltMV movement and replication; however TRV silencing of chloroplast ß ATPase in Nicotiana benthamiana induced severe tissue necrosis when plants were infected by AltMV TGB1L88 but not AltMV TGB1P88, suggesting that ß ATPase selectively responded to TGB1-L to induce defense responses.