Submitted to: Canadian Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2016
Publication Date: 11/15/2016
Citation: Wallis, C.M., Sudarshana, M.R. 2016. Effects of grapevine red blotch-associated virus (GRBaV) infection on foliar metabolism of grapevines. Canadian Journal of Plant Pathology. 38:358-366.
Interpretive Summary: Little is known about how Grapevine red blotch-associated virus (GRBaV) affects grapevine hosts to ultimately cause symptoms of red blotch disease. Therefore, host foliar chemistry was compared between GRBaV-infected and non-infected plants. GRBaV infection resulted in consistent increases in certain amino acids, sugars, and phenolics, which could be associated with host defense induction as well as contribute to symptom expression. These results could lead to the identification of GRBaV tolerance markers by finding germplasm that does not respond to viral infection with host physiology changes. In addition, these findings could contribute to the development of remote sensing technologies to identify early red blotch disease cases via spectral sensing of phenolic compound profiles associated with GRBaV infections.
Technical Abstract: Red blotch disease, caused by Grapevine red blotch-associated virus (GRBaV), is an emerging problem for grapevine production in the United States. However, very little is known about how viruses, such as GRBaV, affect host physiology even though it is crucial to understanding host-pathogen interactions, symptom development, and potential effects on other pathogens and insect pests including potential vectors. Thus, foliar levels of amino acids, sugars, phenolics, and terpenoids were examined in healthy or GRBaV-infected Cabernet Franc (CF) or Cabernet Sauvignon (CS) grapevines both before and after development of red blotch symptoms, in July and September, respectively. Particular amino acids were increased both before and after symptom development for both cultivars, with some of these amino acids having previously defined associations with host defenses. Fructose and glucose were increased in GRBaV-infected CF at both sampling times. However, for CS only glucose was increased in infected grapevines and only when pre-symptomatic. Phenolic levels were greater in GRBaV-infected CF and CS after symptom expression. Terpenoids were greater in infected CF in July only, with no other apparent differences. These results suggest that GRBaV infection induced host defense responses, as characterized by increased amino acids and phenolic compound levels. Defense induction appeared limited to salicylic acid-mediated responses, as jasmonic acid-associated terpenoids were unaffected in September and inconsistently affected in July. Taken together, these results demonstrate the effects of GRBaV infection on host physiology, with shifts potentially associated with symptom development and changes in resistance to other organisms.