Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/21/2005
Publication Date: 3/1/2006
Citation: Harrison Jr, H.F., Peterson, J.K., Snook, M.E. 2006. Simulated drought induces high periderm caffeic acid contents in storage root periderm of greenhouse grown sweetpotatoes. HortScience. 41:277-278. Interpretive Summary: A greenhouse study was conducted to test for the effect of environmental stresses on the level of caffeic acid in sweetpotato skins. Caffeic acid is a natural component of sweetpotato that protects from invasion by insects and diseases. Plants that were exposed to drought stress accumulated much higher levels of caffeic acid than plants that were watered daily; however, caffeic acid levels in plants that were defoliated to simulate insect feeding did not increase. This indicates that environmental factors in addition to genetic differences influence caffeic acid accumulation in sweetpotato skin.
Technical Abstract: This experiment was conducted to determine the effect of simulated drought and insect predation on sweetpotato storage root caffeic acid contents. Average caffeic acid content for the periderm of drought stressed at sweetpotato clones at 1603 µg g dry weight -1 was over twenty five times the average level of non-stressed clones. Periderm caffeic acid levels of all seven clones were higher in periderm of drought stressed plants than of control plants. Periderm caffeic acid contents from sweetpotato plant that were defoliated to simulate insect feeding did not vary from controls. These data suggest that moisture stress may contribute to the variability in periderm caffeic acid contents that we observe in a previous study. Caffeic acid contents in cortex and stele tissue were consistently very low in comparison to periderm levels. Although there were differences in periderm caffeic acid concentration between clones that were not subjected to moisture stress, contents were relatively low for all clones. The differences in caffeic acid contents of moisture stressed sweetpotato clones indicates that under conditions that induce periderm caffeic acid accumulation, there are genetic differences in this capacity. The density of periderm tissue was greater for moisture stressed roots than for control roots for all clones except Jewel and W-325.