【作者】 李永华；

【导师】 孔垂华；

【作者基本信息】 中国农业大学 ， 生态学， 2015， 博士

【摘要】 以次生代谢物变化为主要特征的植物间化学识别与响应,是植物行为生态学研究的主要问题之一。揭示并阐明植物间化学识别与响应机制,对拓宽植物种间化学相互作用的认识具有重要意义。本研究针对化感小麦对与其共存植物的化学识别与响应,探讨异种植物对小麦化感物质的诱导机制。结果显示：(1)小麦和异种植物以相同的比例(1：1,3：3,5：5,10：10,15：15,20：20)共存时,伴生植物对小麦化感物质DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one)的诱导率取决于密度水平；在密度比为5：5时诱导率达到最高。同一密度下不同植物对小麦DIMBOA的诱导率取决于伴生植物的种类。小麦对伴生植物生物量的抑制率在5：5时达到最高,但随着小麦与伴生植物整体播种密度的增加,小麦对伴生植物的抑制逐渐减弱。(2)小麦密度保持5株/盆不变,小麦和异种植物以不同的比例(5：1,5：2,5：3,5：4,5：5,5：6,5：7,5：8,5：9,5：10)共存,10种伴生植物对小麦组织DIMBOA的诱导率与伴生植物种类和密度紧密相关,其中马唐、苘麻、牛筋草、大豆和萝卜在与小麦密度比5：5时,对小麦组织DIMBOA的诱导率达到最高,而稗草、反枝苋、节节麦、野燕麦和日本看麦娘在与小麦密度比8：5时,对小麦组织DIMBOA的诱导率达到最高。(3)小麦对不同播种时期伴生植物的响应显著不同,小麦DIMBOA浓度表现为：先播种伴生植物>同时播种伴生植物和小麦>后播种伴生植物；小麦生物量表现为：先播种伴生植物<同时播种伴生植物和小麦<后播种伴生植物。小麦与伴生植物在根系不分隔及30μm和0.45μm膜分隔三种条件下,小麦对伴生植物均做出可塑性化学响应。而根系在塑料膜完全分隔条件下,伴生植物对小麦组织DIMBOA无诱导效应。表明小麦与伴生植物间识别与响应,是通过地下根系分泌的化学信号物质在土壤中的传递引起的。(4)伴生植物的根系分泌物可诱导小麦DIMBOA的合成,但诱导效应与根分泌物浓度和添加时间显著相关。高浓度根分泌物显著诱导小麦DIMBOA,最大诱导率发生在添加根系分泌物后的第6-9小时。以上结果表明,小麦能够识别异种植物的存在,并通过化感物质DIMBOA的合成及含量变化对伴生植物做出可塑性化学响应。而且这一行为是通过根系分泌的化学信号物质在土壤中的传递进行的,伴生植物对小麦组织DIMBOA的诱导率取决于伴生植物的种类和密度。更多还原

【Abstract】 Chemical recognition and response between plant individuals are critical topics of research on plant behaviors, the main characteristics of which are described by the variation of secondary metabolites in plants. Investigating the mechanisms of recognition and response between plants will contribute to the understanding of interspecific interaction. In this study, the mechanisms of inductive effects of heterogenous plants on the production of allelochemical in wheat were investigated.The results showed that:(1) The proportions between wheat and its coexisting heterogenous plants were1:1,3:3,5:5,10:10,15:15and20:20. The production of DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) in wheat were induced by heterogenous plants, and the inductive effects varied with the density levels. The largest increase was observed at the proportion of5:5. At the same density level, the inductive effects varied with plants species. Wheat suppressed the growth of neighboring heterogenous plants, the largest inhibition rate was observed at the proportion of5:5. The inhibition rate then decreased as densities increased.(2) Keep wheat at the density of5plants/pot, the proportions between wheat and its coexisting heterogenous plants were5:1,5:2,5:3,5:4,5:5,5:6,5:7,5:8,5:9and5:10. The inductive effects of the coexisting plants on the production of DIMBOA in wheat were closely related to the plants species. As densities of coexisting plants increased the concentration of DIMBOA increased at first and then decreased. The largest increase was observed at the density of5plants/pot for the coexisting plants including Digitaria sanguinalis, Abutilon theophrasti, Elensine indica, Glycine max, and Raphanus sativus. While for the coexisting plants Echinochloa crusgalli, Amaranthus retroflexus, Aegilops tauschii, Avena fatua and Alopecurus japonicus, the largest increase was observed at the density of8plants/pot.(3) Seeding time of coexisting heterogenous plants showed significant influence on the production of DIMBOA in wheat and the biomass. The concentration of DIMBOA from high to low was:sowing coexisting plants early> sowing coexisting plants and wheat at the same time> sowing coexisting plants late. The wheat biomass from high to low was:sowing coexisting plants early<sowing coexisting plants and wheat at the same time<sowing coexisting plants late. When the heterogenous plants and wheat were planted with the treatments of root contact and root separation (30um nylon mesh,0.45μm nylon mesh), wheat could recognize the coexisting heterogenous plants and make a biochemical response to them. When the roots of the heterogenous plants and wheat were separated completely (plastic film), no inductive effects of the production of DIMBOA in wheat were observed. (4) The production of DIMBOA in wheat could be induced by the root exudates of the coexisting plants, while the inductive effects were significantly correlated with the addition time and concentration of the exudates. High concentration of root exudates increased the DIMBOA concentration, and the significant increase occurred at6h and at9h of incubation.The results suggested that wheat could recognize the coexisting heterogenous plants, and make a plastic chemical response by the variation of allelochemical DIMBOA in wheat. Wheat recognized and response to the coexisting heterogenous plants through information chemicals in the soil released from the roots of the coexisting plants. The inductive effects of heterogenous plants on the production of DIMBOA in wheat varied with the density levels and species of coexisting plants.更多还原