Growth stimulatory substances for vesicular-arbuscular mycorrhizal fungi in citrus juice sediment extracts.

ISHII, TAKAAKI¹, MAKOTO KURAMOTO², NAOKI NAKAMURA³, MASARU YANO³, KAZUO SANO³, JIRO AIKAWA⁴, LEONARD SAMITA WAMOCHO¹, ISAO MATSUMOTO⁴ & KAZUOMI KADOYA⁴

¹Fac. Educ., Ehime Univ., JAPAN, ²Adv. Instr. Center Chem. Anal., Ehime Univ., JAPAN, ³ Fruit Growers' Coop. Assn. Ehime Prefect., JAPAN, ⁴Fac. Agri., Ehime Univ., JAPAN.

We reported that the 25% methyl alcohol (MeOH) eluates of citrus juice sediment greatly stimulated the hyphal growth of vesicular-arbuscular mycorrhizal (VAM) fungi and the VAM development of citrus roots (Aikawa et al, 1997). In this study, we tried to isolate and identify some of the VAM-stimulatory substances in citrus juice sediment extracts.

Two kinds of VAM-stimulatory substances were isolated from the 25% MeOH eluates of satsuma mandarin juice sediment fractionated by flash chromatography and high pressure liquid chromatography. One of them was identified as hesperetin-7-fÁ-rutinoside (hesperidin), and the other was naringenin-7-fÁ-rutinoside (narirutin). These flavonoids significantly stimulated the in vitro hyphal growth of Gigaspora margarita.

These results suggest that some flavonoids which are contained in plant tissues may act as signal molecules in VAM symbiosis.