Chlorogenic acid content in sweetpotato germplasm: Possible role in disease and pest resistance

Fourteen sweetpotato clones representing wide genetic diversity were field grown under low stress conditions. Chlorogenic acid contents were determined in periderm and cortex tissues of these clones. On dry weight basis, chlorogenic acid content in the periderm tissues ranged from 33 to 214 g g⁻¹ dry tissue and in the cortex from 1416 to 4213 g g⁻¹ dry tissue (181 to 1384 g g⁻¹ on fresh weight basis). In vitro bioassays were done to assess the bioactivity of chlorogenic acid seed germination of proso millet (Panicum milliaceum L.), growth of four sweetpotato pathogenic fungi and growth and survival of diamondback moth larvae (Plutella xylostella). The highest levels of chlorogenic acid occurring in sweetpotato cortex tissue, exceeded the lowest concentrations that inhibited the growth and survival of diamondback moth larvae and the growth of three of four sweetpotato pathogenic fungi tested.