【作者】 杨莉；

【导师】 杨利民；

【作者基本信息】 吉林农业大学 ， 药用植物， 2011， 博士

【摘要】 加拿大蓬(Erigeron canadensis)为菊科飞蓬属植物,原产于北美洲,是早期传入我国的外来入侵种,目前广泛分布于我国南北各省区,已成为农田、荒地的恶性杂草。化感作用是外来种入侵的重要机制之一,也是实现其资源化利用,变被动防除为主动控制的重要手段。本文对加拿大蓬的化感作用和资源化利用等进行了相关研究,主要研究结果如下：1.研究了渗透胁迫对化感作用研究的干扰,建立了较为规范的水溶物化感作用生物测定方法。以此为前提,采用多个受体植物测定了加拿大蓬水提液的化感作用潜力。结果表明：加拿大蓬水提液对种子的化感作用表现为种子萌发率降低、种子萌发时间延迟；对幼根生长具有广谱的抑制作用；对幼茎生长的影响因种而异,呈现为抑制或“低促高抑”；对成熟植株主茎生长有抑制作用,改变光合产物在受体植物根、茎、叶等部位的分配,并造成其生物量积累障碍。以玉米为例,加拿大蓬水提液对其不同生长发育时期的影响大小排列顺序为：幼苗期>吐丝期>灌浆期>成熟期>种子萌发阶段。采用半密闭容器法对加拿大蓬挥发油的化感作用进行了生物测定,并对采用挥发、淋溶2种不同途径释放挥发油中次生代谢产物对受体植物造成的影响进行了差异比较。结果发现：挥发油对种子萌发和幼苗生长具有不同程度的抑制作用。其中,以挥发的方式作用于受体植物时,茎长生长存在“低促高抑”现象,对根长的抑制作用明显强于茎长；而挥发油淋溶物(以下简称芳香水)同时抑制了幼根、幼茎的发育。3种受体植物中小白菜对加拿大蓬挥发油的化感作用最为敏感,苦苣受芳香水的影响最大。说明以不同途径释放加拿大蓬挥发油中化感物质时,其化感作用存在差异。将加拿大蓬植株进行自然腐解,研究其腐解物对土壤中微生物数量的影响,结果显示：腐解物对细菌有抑制作用,细菌比例减小；对真菌和放线菌数量增加有促进作用,其比例增大,含有加拿大蓬腐解物的土壤有从“细菌型”土壤向“真菌型”土壤转变的趋势。其次,以混有加拿大蓬自然腐解物的土壤进行试验,结果发现受体植物种子萌发率和株高降低,但叶面积和生物量显著增加,受体表现出“粗、矮”的特点。通过上述研究证明,加拿大蓬淋溶物、挥发油、芳香水、腐解物均具有不同程度的化感作用潜力,加拿大蓬化感作用的释放途径是多种多样的。2.采用3种受体植物、3个检测指标调查了生育期内加拿大蓬3种主要化感物质(淋溶物、挥发油、芳香水)的化感作用动态变化,并对其相关影响因素进行了分析。结果表明27条曲线相似性较低,其变化趋势因受体、检测指标、供体生长发育阶段等出现了多种变化。总体看来,加拿大蓬主茎旺盛生长时化感作用最强,幼苗期和孕蕾期-始花期是加拿大蓬化感作用最弱的两个时期。研究发现,浓度、受体植物种类、受体生长发育阶段、化感物质种类及释放途径、化感物质间的交互作用、加拿大蓬各部位生长发育、加拿大蓬次生代谢物质积累、土壤及植株本身矿质元素含量以及气象因子都与加拿大蓬化感作用变化存在显著或极显著的相关关系。3.对加拿大蓬入侵群落中结构特征进行分析,结果显示：在加拿大蓬生育期内,翼化感作用降低时,样方内Sinpson指数、Shannon指数和Brillouin指数增加,推测加拿大蓬化感作用影响了种群调节。相关分析结果显示加拿大蓬淋溶物的化感作用与物种数、多样性指数、均匀度指数等达到显著或极显著负相关,其数学模型呈指数关系,最高拟合系数可达0.734,具有显著意义,说明淋溶物是加拿大蓬的入侵是群落中中多样性和均匀度变化的重要影响因素。除此之外,样方内加拿大蓬表现出较大优势度还与其光合能力有关。虽然与伴生种北山莴苣等相比,加拿大蓬不具有光合优势,但随着生育进程的发展,其净光合速率增加、蒸腾速率减小、水分利用效率增加,表明其具有较强的光合能力和抗旱能力,更适应向阳撂荒地夏季高温干旱的生境,从而表现出较强的入侵性。4.对加拿大蓬中化感物质进行活性追踪,结果表明：加拿大蓬挥发油的化感作用与其含有丰富的萜类物质有关,其中主要的化感活性物质为柠檬烯,其在挥发油中相对含量达到55.49%。水提液中主要化感活性物质为苯甲酸类衍生物,包括苯甲酸、苯乙酸、香草醛、香草酸、丁香醛、丁香酸等物质。利用HSCCC、HPLC和反复柱层析,从加拿大蓬水提液中分离得到了4个单体物质,分别是：化合物A(香草酸)、化合物B、化合物C(槲皮素)、化合物D(木犀草素)。其中香草酸为首次从该植物中得到。5.通过加拿大蓬对受体植物幼苗和成株化感作用机制的研究,表明加拿大蓬对幼苗的化感作用机制包括影响种子吸水作用,可溶性蛋白含量、激素水平(GH、GA、CTK、ABA)和保护酶活性(POD、SOD、CAT)。对成株的化感机制包括影响受体光合色素含量,受体叶片结构参数和气体交换参数,以及改变光合产物的分配。6.加拿大蓬水提液除对杂草具有抑制活性外,还对食源性细菌和真菌具有抑菌活性。水提液的氯仿萃取物对链球菌、丙酮萃取物对沙门氏菌的抑菌效果最好；正丁醇萃取物对真菌有较好的抑菌效果。20g/L的正丁醇物对人参立枯病的抑菌率为88.63%,相当于10 g/L代森锰锌对人参立枯病的抑菌效果。加拿大蓬挥发油对6种食源性致病菌有良好的广谱抗菌作用,其中对志贺氏菌的MIC为5 g/L,为高度敏感。对人参2种致病真菌的抑菌效果较明显,挥发油10、20 g/L溶液分别相当于代森锰锌5、10 g/L对人参立枯病的杀菌效果,其20 g/L的溶液对人参黑斑病的抑菌率为100%。更多还原

【Abstract】 Erigeron canadensis is an exotic, invasive species from North American, which has now spread into many regions of China. This plant shows strong allelopathy to native species, which endangers agricultural production, biodiversity and so on. So it is very important to research its chemical invasion mechanism to prevent its spread to more zones. On the other hand, finding methods of rational development and sustained utilization of E. Canadensis may be a more scientific approach to controlling this rich natural resource.Therefore, both the allelopathy and the utilization of E. Canadensis, as well as the results, are discussed below.1. To establish a formal bioassay of eluviated matter, the effect of osmotic stress on biossay of allelopathy was first studied. Taken its results as a premise,the allelopathic potential of water extracts of Erigeron canadensis (WEEC) was investigated, using several receptors. The results showed that WEEC had many adverse effects on seeds and seedlings, such as a decline in germination rate, a delay in germination time; growth inhibition of roots; high concentrations caused the caulicle to be inhibited, while low concentrations caused the caulicle either to be inhibited or to be accelerated, depending on the species of the specimen.The stems of adult plants were lower and more slender when irrigated with WEEC; the distribution of photosynthetic products in root, stem, leaves and other parts was changed, and the dry matter accumulation was also restrained. Take maize as an example, the influence of WEEC on different growing development periods was:seedling stage>silking stage>filling period>ripening period> seed germination.Allelopathy of volatilility from E. canadensis was studied in a semi-closed container, and the effects of its allelochemicals released with volatilization or eluviations on acceptor plants were compared. The results showed that the seed germination and seedling growth were affected differently by volatile oil (VOEC) and its eluviations (abbreviate:aqua aromatic, AAEC). The acceptors’stem lengths were accelerated with low VOEC concentration and inhibited with high concentration, and the inhibitation of the stems was significantly smaller than that of the radix. In the treatment of AAEC, both stems and roots were strongly inhibited. Brassica cantpestris spp. Chinens was the most sensitive plant to the chemical components of VOEC, while the Sonchus oleraceus L. was the most easily influenced by AAEC. All these showed that the allelochemicals released with different modes could result in different responses of acceptors.The effects of naturally decomposed of E. canadensis plants on soil microbial communities, seed germination and seedling growth were also studied. It was found that, compared with th control samples, allelochemicals of decaying substance (DSEC) changed microbial communit structures with a decrease of bacteria ratio, and an increase of actinomyces and fungi ratios. Th results indicated that soil mixed with DSEC had a tendency to be changed from "bacteria-rich’ to "fungi-rich". Furthermore, the acceptors cultured on the soil with DSEC showed a decrease o germination rate and stem height, but the leaf area and biomass increased significantly.The results above indicated that WEEC, VOEC, AAEC, DSEC had different allelopathic potential, and the releasing mode of E. canadensis was various.2. Allelopathy dynamic changes of 3 main allelochemicals in E. canadensis (WEEC, VOEC, AAEC) were investigated with 3 acceptors,3 indexes during the growing season, and the relativity was analyzed between the changes and influence factors. It was found that the 27 curves were dissimilar, they were changed with the acceptors, indexes, growing periods. In general, the period that main stem growing quickest stage had the strongest allelopathy, and the bud stage was the weakest period. It also found that, besides the influence factors mentioned above, there some other factors showing significant correlated relationship with dynamic changes of allelochemicals in E. canadensis, such as solution concentration, releasing mode, interaction of allelochemicals, growth of different plant parts, mineral elements in soil and plants, and weather.3. The population structure and dynamics with which E. canadensis invaded was analyzed. The result indicated that Simpson index, Shannon index, Brillouin index of quadrats increased when allelopathy of E. Canadensis decreased, which suggested the allelopathy of E. Canadensis participated in the self-regulation of population. The correlation analysis showed significant or highly significant negative correlations between allelopathy and indexes. The relationship between them was exponential(p<0.05), which means the eluviated matter of E. Canadensis was an influential factor in the change of evenness and species diversities in plant communities having a dominant presence of E. canadensis.Photosynthetic capacity of E. canadensis was one reason for its marked dominance in various plant communities.Thoughitsnet photosynthetic rate was not any greater than that of accompanying species, such as Lactuca sibicica, the water use efficiency of E. canadensis increased and its transpiration rate decreased with its growth, which means the plant had strong photosynthetic ability and drought resistance, it was more adapted to high temperatures and dry environmental conditions in summer, thus showing a greater biological invasion ability.4. Allelochemicals extraction and separation of E. canadensis withthe bioactivity-guided fractionation and isolation principle were carried out. The result showed that there were abundant terpenoids, especially monoterpene, in VOEC. The most important allelochemicalwas limonene with the relative content of 55.49%. Allelochemicals in WEEC were benzoic acid and its derivatives, including phenylacetic acid, vanillin, vanillic acid, syringaldehyde, syringic acid, etc. Four compounds were isolated from water extract of E. canadensis with HSCCC, HPLC and repeating column chromatography. Thestructures of 3 compounds were determined by using chemical and spectral methods as syringaldehyde, luteolin, quercetin.5. Allelopathy mechanisms of E. canadensis were investigated. The result suggested the allelopathy mechanism on seedlingsincluded the restraint of water-absorbing capacity in seed germination, a decline in the content of soluble proteins, activity of SOD, POD, CAT and plant hormones (GH、GA、CTK、ABA) level changed. The effect on adult plants were the damage of photosynthesis, including the influence on the content of photosynthetic pigments, structure parameter and gas exchange parameters of leaves, and distribution of photosynthate.6. Except the activity of weed controlling, water extract of E. Canadensis showed an antagonistic activity on bacterial and fungal growth. The antibacterial activities of chloroform extract on streptococcus, acetone extract on salmonella, n-butanol extract on fungi, were the best. The inhibitory percentage of 20 g/L n-butanol extract on Alternaria anax Whetz was 88.63%, which showed similar bacteriostatic effects with 10 g/L mancozeb.The results of the antimicrobial test of essential oil showed that VOEC had a significant broad spectrum of antimicrobial activity against all 6 food-borne pathogens and 2 fungi tested. Especially, Shigella dysenteriae, Alternaria panax Whetz and Rhizoctonia solani were most sensitive to it. The inhibitory percentage of 20 g/L VOEC on Rhizoctonia solani was 100%, and 10,20 g/L VOEC showed similar bacteriostatic effect with 5,10 g/L mancozeb to Alternaria panax Whetz.更多还原