苎麻根际土壤水浸提液化感潜力评价

【目的】通过苎麻根际土壤水浸提液有机化合物的分离鉴定及生物学实验，探讨了苎麻败蔸与化感作用的关系。【方法】运用气相色谱-质谱联用技术 (GC-MS)，对苎麻根际土壤的不同极性有机溶剂萃取液进行了物质成分分析；采用室内生物测定方法，研究了不同浓度苎麻根际土壤水浸提液对萝卜、油菜、拟南芥 3 种植物的化感效应；并应用实时定量 PCR 技术 (QPCR)，测定了不同浓度根际土壤水浸液处理后拟南芥其抗逆基因 RD29A (AT5G52310) 和 RD29B (AT5G52300) 及生长素合成相关基因 YUC1 (AT4G32540) 的相对表达水平。【结果】四种不同极性有机溶剂萃取液经 GC-MS 检测共鉴定出 51 种有机化学物质，包括烃类及其衍生物、甾类化合物、苯甲酸及其衍生物、酚类、萜类、含氮类等已被报道具有化感活性的化合物。不同浓度苎麻根际土壤水浸液对 3 种不同植物的下胚轴长及根长的化感效应具有差异性，随着浸提液浓度增加，对油菜及拟南芥抑制作用越显著，但对萝卜的影响不显著。QPCR 检测结果表明，拟南芥的 RD29A、RD29B、YUC1 这 3 种基因的表达量随水浸提液浓度增加均降低。【结论】苎麻根际土壤中含有抑制自身生长的潜在化感物质豆甾-4-烯-3,6-二酮，2,5-二叔丁基苯酚，邻苯二甲酸二乙酯，6,6-二甲基-1,3-庚二烯-5-醇，羊毛甾-8,24-二烯-3,22-二醇。高浓度苎麻根际土壤水浸提液对供试三种植物下胚轴长及根长具有抑制效果，因此，连作导致的化感物质累积可能是连作导致苎麻败蔸的原因之一。

Allelopathic potential evaluation of water extracts from ramie rhizosphere soil

[Objectives] To study the relationship between root-rot and allelopathy of ramie,the organic compounds and allelopathic effect of rhizosphere oil water extracts were determined.[Methods] The GC-MS was used to identify the compounds of the different polarity organic solvent extracts.The allelopathy potentials of different concentrations of rhizosphere soil water extract were bioassayed for Raphanus sativus,Brassica rapa and Arabidopsis thaliana;and QPCR was applied to determine the gene expression (RD29A,RD29B,YUC1),which was related to stress tolerance and auxin synthesis.[Results] Fifty-one compounds in four different polar organic solvent extracts were identified,including hydrocarbons and their derivatives,steroid compounds,benzoic acid and its derivatives,phenols,terpenoids,nitrogenous substances and so on,and part of them is allelophathic substance.The different concentrations of rhizosphere soil water extracts had obvious allelopathy on hypocotyl and root length of three plants to different extent.The inhibition to Brassica rapa and Arabidopsis thaliana was more significant with the increase of concentration of water extracts,less significant to Raphanus sativus.The QPCR testing results showed that the gene expression relative quantity of RD29A,RD29B and YUC1 generally decreased with the increase of the concentration of water extracts.[Conclusions] Raime rhizosphere soil is proved containing potential allelochemicals of cholest-4-ene-3,6-dione,phenol,2,5-bis(1,1-dimethylethyl)-,diethyl phthalate,6,6-dimethyl-1,3-heptadien-5-ol,lanosta-8,24-diene-3,22-diol.The hypocotyl and root length are mainly allelopathic effected at higher concentrations of rhizosphere soil water extracts.Therefore,we infered the allelopathy is one of the causes associated with ramie succession cropping obstacle and root-rot.