Accumulation and Antifungal Spectrum of Rhaphiolepsin as a Second New Phytoalexin in Rhaphiolepis umbellata Makino

Abstract

Accumulation and antifungal activity of a second newly isolated phytoalexin of Rhaphiolepis umbellata Makino, rhaphiolepsin, were described. The phytoalexin was accumulated in the leaves infected with Entomosporium mespili or Pestalotiopsis sp. The accumulation of 4'-methoxyaucuparin, the first phytoalexin of R. umbellata, was started one day after inoculation and it remained stably for about 6 days and then declined during the next 6 days. On the other hand, rhaphiolepsin started to accumulate in the leaves at the 8th and reached the maximum accumulation of 2.147μg/g fresh leaves at 28th days after inoculation. The inhibitory action of rhaphiolepsin against the fungi was stronger than that of 4'-methoxyaucuparin.