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首页> 外文学位 >Interactive effects of drought and infection by a xylem-limited bacterial pathogen on the ecophysiology of a liana and on subsequent attack by an insect herbivore.
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Interactive effects of drought and infection by a xylem-limited bacterial pathogen on the ecophysiology of a liana and on subsequent attack by an insect herbivore.

机译：干旱和木质部受限细菌病原体感染对藤本植物的生态生理以及随后被食草动物侵袭的相互作用的影响。

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摘要

Two stresses of particular importance to plants are drought and pathogens. One major plant pathogen is Xylella fastidiosa, a xylem-limited bacterial pathogen. This organism causes leaf scorch symptoms across its extensive host range. Previous observations suggested that leaf scorch symptoms were more severe if plants were experiencing other environmental stresses simultaneously. However, no experimental studies have tested this hypothesis. Parthenocissus quinquefolia, Virginia creeper, is a widespread liana throughout the eastern half of the United States. This species is an important component of natural forest communities, as well as ornamental plantings. It is susceptible to infection by X. fastidiosa, and displays prominent leaf scorch symptoms. My objectives in this study were to test the interaction between X. fastidiosa-infection and drought using P. quinquefolia as the host plant. I also wanted to assess how pathogen and water stress induced changes in P. quinquefolia affected subsequent susceptibility to attack by a non-vector insect herbivore. In two experiments in 1999 and 2000, I manipulated soil moisture levels and pathogen infection. Leaf scorch symptoms of infected plants were more severe and progressed further along the stem in low water compared to high water treatments. P. quinquefolia growth was additively reduced by low water and infection. Whole shoot hydraulic conductance and xylem vessel lengths were reduced by both low water and infection, while only low water increased embolism and reduced vessel diameter. Thus, the major effect of infection on hydraulic conductance was caused by clogging of vessels. P. quinquefolia responded initially to low water and infection by reducing stomatal conductance. This response maintains relatively high leaf water potentials during drought. Chlorophyll fluorescence measurements showed that P. quinquefolia has an efficient means of dissipating excess light energy, avoiding irreversible photoinhibitory damage. However, severe stress induced by infection and low water eventually led to decreases in photosynthesis and accelerated leaf senescence. Low water and infection treatments reduced relative water content and leaf nitrogen contents of leaves, while increasing the carbon:nitrogen ratio. In whole leaf assays, Japanese Beetles (Popillia japonica) preferred and consumed the most leaf tissue in high water, non-infected treatments compared to stressed treatments.
机译：对植物特别重要的两个压力是干旱和病原体。一种主要的植物病原体是木糖受限的细菌病原体，即木糖。这种生物在其广泛的宿主范围内引起叶片焦烧症状。以前的观察结果表明，如果植物同时遭受其他环境胁迫，则叶子的焦烧症状会更加严重。但是，没有实验研究证明了这一假设。爬山虎爬山虎（Parthenocissus quinquefolia），弗吉尼亚爬山虎，在美国东半部广泛分布于藤本植物中。该物种是天然森林社区以及观赏性植物的重要组成部分。它很容易被黑僵菌感染，并表现出明显的叶子焦烧症状。我在这项研究中的目标是使用西洋参假单胞菌作为寄主植物来测试耐腐假单胞菌感染与干旱之间的相互作用。我还想评估病原体和水分胁迫如何导致西洋参假单胞菌的变化影响随后的非媒介昆虫食草动物的易感性。在1999年和2000年的两个实验中，我控制了土壤湿度和病原体感染。与高水处理相比，在低水情况下，被感染植物的叶子焦烧症状更为严重，并且沿茎部进一步发展。低水和感染会进一步增加西洋参的生长。低水和低感染都降低了整苗的水力导通和木质部血管的长度，而只有低水会增加栓塞和减小血管直径。因此，感染对水力传导的主要影响是由血管阻塞引起的。西洋参最初通过降低气孔导度来应对低水和感染。这种反应在干旱期间保持较高的叶片水势。叶绿素荧光测量表明，西洋参具有消散多余光能的有效方法，可避免不可逆的光抑制损伤。然而，由感染和低水诱导的严重胁迫最终导致光合作用降低和叶片衰老加速。低水分和感染处理降低了叶片的相对水含量和叶片氮含量，同时增加了碳氮比。在全叶分析中，与胁迫处理相比，日本甲虫（Popillia japonica）在高水，未感染处理中更喜欢并消耗最多的叶子组织。

著录项

  • 作者

    McElrone, Andrew J.;

  • 作者单位

    University of Maryland, College Park.;

  • 授予单位 University of Maryland, College Park.;
  • 学科 Biology Botany.;Biology Plant Physiology.;Biology Ecology.
  • 学位 Ph.D.
  • 年度 2001
  • 页码 128 p.
  • 总页数 128
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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