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Global Analysis of Tomato Gene Expression During Potato spindle tuber viroid Infection Reveals a Complex Array of Changes Affecting Hormone Signaling

April 2012 , Volume 25 , Number  4
Pages  582 - 598

Robert A. Owens,1 Kimberly B. Tech,1 Jonathan Y. Shao,1 Teruo Sano,2 and C. Jacyn Baker1

1Molecular Plant Pathology Laboratory (USDA/ARS), 10300 Baltimore Avenue, Beltsville, MD 20705, U.S.A.; 2Plant Pathology Laboratory, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan

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Accepted 18 December 2011.

Viroids like Potato spindle tuber viroid (PSTVd) are the smallest known agents of infectious disease—small, highly structured, circular RNA molecules that lack detectable messenger RNA activity, yet are able to replicate autonomously in susceptible plant species. To better understand the possible role of RNA silencing in disease induction, a combination of microarray analysis and large-scale RNA sequence analysis was used to compare changes in tomato gene expression and microRNA levels associated with PSTVd infection in two tomato cultivars plus a third transformed line expressing small PSTVd small interfering RNAs in the absence of viroid replication. Changes in messenger (m)RNA levels for the sensitive cultivar ‘Rutgers’ were extensive, involving more than half of the approximately 10,000 genes present on the array. Chloroplast biogenesis was down-regulated in both sensitive and tolerant cultivars, and effects on mRNAs encoding enzymes involved in the biosynthesis of gibberellin and other hormones were accompanied by numerous changes affecting their respective signaling pathways. In the dwarf cultivar ‘MicroTom’, a marked upregulation of genes involved in response to stress and other stimuli was observed only when exogenous brassinosteroid was applied to infected plants, thereby providing the first evidence for the involvement of brassinosteroid-mediated signaling in viroid disease induction.

This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 2012.