title: Rice seedlings release momilactone B into the environment.
abstract: Since the growth inhibitor momilactone B was found recently in root exudates of rice (Oryza sativa L.), 3-day-old rice seedlings were transferred to hydroponic culture and the level of momilactone B released into the environment from the seedlings was measured. At day 15 after transfer, the level of momilactone B in the culture solution was 1.8 nmol per seedling compared with endogenous levels of 0.32 and 0.63 nmol per root and shoot, respectively, suggesting that rice seedlings actively releases momilactone B into the culture solution. This release must occur from the roots because only rice roots were immersed in the culture solution. Momilactone B inhibited the growth of ten cress (Lepidium sativum L.) seedlings at concentrations greater than 3 microM. Ten rice seedlings were incubated with ten cress seeds in a Petri dish containing 1 ml of medium, the medium contained 18 nmol of momilactone B, which came to 18 microM. This level of momilactone B was enough to reveal growth inhibition of the cress seedlings. Release level of momilactone B and its effectiveness as a growth inhibitor suggest that it 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. hisashi@ag.kagawa-u.ac.jp
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kato-Noguchi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ino
mesh_terms: D019607:Brassicaceae / Q000187:drug effects / Q000254:growth & development; D004224:Diterpenes / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D004777:Environment; D018527:Hydroponics; D007783:Lactones / Q000378:metabolism* / Q000494:pharmacology; D015394:Molecular Structure; D012275:Oryza / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D036226:Seedlings / Q000378:metabolism*
chemical_list: D004224:Diterpenes; D007783:Lactones; C477203:momilactone B