|TADYCH, MARIUSZ - Rutgers University|
|VORSA, NICHOLI - Rutgers University|
|WANG, YIFEI - Rutgers University|
|BERGEN, MARSHALL - Rutgers University|
|JOHNSON-CICALESE, JENNIFER - Rutgers University|
|WHITE, JAMES - Rutgers University|
Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2015
Publication Date: 8/14/2015
Publication URL: https://handle.nal.usda.gov/10113/61591
Citation: Tadych, M., Vorsa, N., Wang, Y., Bergen, M., Johnson-Cicalese, J., Polashock, J.J., White, J. 2015. Interactions between cranberries and fungi: the proposed function of organic acids in virulence suppression of fruit rot fungi. Frontiers in Microbiology. 35:177. doi: 10.3389/fmicb.2015.00835.
Interpretive Summary: Cranberry is very susceptible to fruit rot that is caused by a number of different fungal pathogens. Losses to fruit rot in the field can reach 100% without the use of effective fungicides. One goal of our research program is to develop varieties that are rot resistant. We examined the possibility that certain organic acids in cranberry fruit suppress development of fruit rot in resistant selections. We found that benzoic and quinic acids, which naturally occur in cranberry fruit, suppressed fungal growth and development of fruit rot. We propose that variation in the levels of these compounds in the fruit influence development of rot, with varieties high in these compounds being more rot resistant. This offers a target for breeding rot resistant cranberry with the goal of reducing fungicide use. These results will be useful to cranberry research scientists and breeders as well to research scientists studying other fruits that are susceptible to fruit rot pathogens.
Technical Abstract: Cranberry fruit are a rich source of bioactive compounds that may function as constitutive or inducible barriers against rot-inducing fungi. The content and composition of these compounds change as the season progresses. Several necrotrophic fungi cause cranberry fruit rot disease complex. These fungi remain mostly asymptomatic until the fruit begins to mature in late August. Temporal fluctuations and quantitative differences in selected organic acid profiles between fruit of six cranberry genotypes during the growing season were observed. The concentration of benzoic acid in fruit increased while quinic acid decreased throughout fruit development. In general, more rot-resistant genotypes showed higher levels of benzoic acid early in fruit development and more gradual decline in quinic acid levels than that observed in the more rot-susceptible genotypes. We evaluated antifungal activities of selected cranberry constituents and found that most bioactive compounds either had no effects or stimulated growth or reactive oxygen species (ROS) secretion of four tested cranberry fruit rot fungi, while benzoic acid and quinic acid reduced growth and suppressed secretion of ROS by these fungi. We propose that variation in the levels of ROS suppressive compounds, such as benzoic and quinic acids, may influence virulence by the fruit rot fungi. Selection for crops that maintain high levels of virulence suppressive compounds could yield new disease resistant varieties. This could represent a new strategy for control of disease caused by necrotrophic pathogens that exhibit a latent or endophytic phase.