Submitted to: Physiological and Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 10, 2010
Publication Date: June 10, 2010
Citation: Baker, C.J., Owens, R.A., Whitaker, B.D., Mock, N.M., Deahl, K.L., Roberts, D.P., Averyanov, A.A. 2010. Effect of viroid infection on the dynamics of phenolic metabolites in the apoplast of tomato. Physiological and Molecular Plant Pathology. 74:214-220.
Interpretive Summary: Potato spindle tuber viroid (PSTVd) infects potato and tomato crops causing devastating losses. PSTVd is a very small strand of nucleic acid that can spread throughout the plant causing a systemic infection. We studied this viroid on tomato, measuring biochemical changes as the PSTVd spread from leaf to leaf throughout the plant. We discovered that several unique chemicals are produced only when the PSTVd enters a new area of the tomato and starts to multiply. These chemicals could be critical for PSTVd multiplication and may provide a means to control the disease by interfering with the viroid multiplication. This information will be of use to us and other plant scientists who are devising new strategies to improve disease resistance to viroids.
Plants are capable of producing a wide array of secondary metabolites which serve many functions, due to their bioactive, redox or structural properties. Subtle changes in the external or internal environment can cause significant changes in the array of secondary metabolites presented in the tissue. During the last 10 years we have begun to learn that these metabolites play critical roles both in plant development as well as protection against biological and abiotic stresses. Here we examined changes in the apoplastic phenolics caused by the systemic infection of Potato Spindle Tuber Viroid (PSTVd) as it spreads through the tomato plant. The apoplast fluid from leaves at different distances from the infection site over a 5 week period were examined by HPLC-UV. Three general patterns of change were found in the phenolics, which remained similar to the control, increased transiently at the onset of the viroid infection, or decreased after viroid infection. An important basic finding of this study is that the composition of apoplastic metabolites is dynamic, changing with time and leaf development. In addition it demonstrates that the secondary metabolites of the apoplast respond to the presence of the viroid in the symplast of the cell will affect the phenolics constituents in the apoplast.