Analysis of metabolites in root exudates from allelopathic and non allelopathic rice seedlings

摘要

The root exudates of two rice accessions [allelopathic rice (PI312777) and non-allelopathic (rice Lemont)] seedlings, planted in sand under natural condition, were collected using a circulation system. The diethyl ether extracts from the root exudateswere detected with GC-MS and the individual compounds were identified by comparing their mass spectra with those from NIST and Wiley Library of mass spectral database. Sixty three compounds were detected in root exudates of PI312777 and 77 compounds inLemont. The substances were terpenoids, phenols (quinones), aldehydes (ketones), heterocyclic alcohols, ethers, hydrocarbons etc. The differences existed in quantity, content and chemical structure of compounds in the metabolites of both rice accessions.There were 28 homogeneous compounds, accounting for 91.11% of the total content in PI312777 and 73.95% of the total content in Lemont, respectively. Thus both rice accessions possess the same or similar metabolic pathway. The rice allelopathy might result from the suitable combination of all substances in rice root exudates. Based on these results, the inhibitory activity of five oxygenic cyclomonoterpenoids (molecular formulae and molecular structures similar to compounds detected in rice root exudates) were confirmed in bioassay. Most of the oxygenic cyclomonoterpenoids were inhibitory to root length of barnyardgrass at higher concentration (>5 ppm) but stimulatory at lower concentration (