title: Isolation and identification of a potent allelopathic substance in rice root exudates.
abstract: A search for growth inhibitors in rice root exudates was undertaken in order to clarify the allelopathic system in rice (Oryza sativa L.). Rice seedlings inhibited the growth of cress (Lepidium sativum L.) and lettuce (Lactuca sativa L.) seedlings when the cress and lettuce were grown with rice seedlings. The putative compound causing the inhibitory effect of rice seedlings was isolated from their culture solution, and the chemical structure of the inhibitor was determined by spectral data as momilactone B. Momilactone B inhibited the growth of cress and lettuce seedlings at concentrations greater than 3 and 30 microM, respectively. The concentration of momilactone B was 3.4 and 1.1 nmol per seedling in the culture solutions of husked and non-husked rice seedlings, respectively. These results suggest that rice seedlings may release momilactone B into the environment and the stress caused by the husk-treatment may increase the amount of momilactone B released. Thus, momilactone B may play an important role in rice allelopathy.
authors.affiliation: Department of Biochemistry and Food Science, Faculty of Agriculture, Kagawa University, Miki, Kagawa 761-0795, Japan Department of Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi, Yokohama 223-0061, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kato-Noguchi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ino
authors.forename: Noriko
authors.initials: N
authors.lastname: Sata
authors.forename: Shosuke
authors.initials: S
authors.lastname: Yamamura