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It’s good to be green: A link between photosynthesis and polerovirus infection revealed by high-resolution mass spectrometry
S. L. DEBLASIO (1), R. Johnson (2), J. Chavez (2), M. Alexander (3), K. Parks (4), J. Ramsey (4), A. Karasev (5), S. M. Gray (6), J. E. Bruce (2), M. J. MacCoss (2), M. Cilia (7). (1) USDA-Agricultural Research Service; Boyce Thompson Institute for Plant Research, Ithaca, NY, U.S.A.; (2) Department of Genome Sciences, University of Washington, Seattle, WA, U.S.A.; (3) Department of Plant Pathology and Plant-Microbe Biology, Cornell

Repression of photosynthesis is a common signature of virus infection. Poleroviruses are among the best-studied, phloem-restricted viruses. Symptoms are characterized by general leaf or interveinal chlorosis associated with a reallocation of carbohydrates and starch deposition in chloroplasts. However, the direct effects of infection on the host photosynthetic machinery are not well described. Using a combination of chemical cross-linking and affinity purification coupled to high-resolution mass spectrometry, we identified over 300 plant proteins with plastid-related functions including 126 involved in photosynthesis pathways, to directly or indirectly bind with the major and/or minor polerovirus capsid proteins or the P1 replication-associated protein. Virus-induced gene-silencing (VIGS) of phytoene desaturase, a key enzyme in chlorophyll biosynthesis, resulted in an increase in virus titer during plant infection whereas silencing of <i>PSBQ2, </i>a component of the oxygen-evolving complex identified as directly binding to virus, had a negative effect on virus titer indicating that poleroviruses may use different strategies to manipulate photosynthesis to ensure successful propagation in plants. Understanding the mechanisms involved in photosynthetic regulation of polerovirus infection could be useful in developing strategies to prevent infection and/or viral transmission.

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