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首页> 外文学位 >'Candidatus Liberibacter' in four indigenous Rutaceous species from South Africa.
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'Candidatus Liberibacter' in four indigenous Rutaceous species from South Africa.

机译：来自南非的四种本土芸香科物种中的“ Candidatus Liberibacter”。

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摘要

Greening disease in South Africa is associated with a phloem-limited member of the Alphaproteobacteria known as 'Candidatus Liberibacter africanus' (Laf). Spread of this bacterium is assisted by the flight and feeding activities of its triozid vector, Trioza erytreae. In addition to Laf, 'Candidatus Liberibacter africanus subsp. capensis' (LafC) has been described from this country. LafC is widely associated with Calodendrum capense, an indigenous Rutaceous species. This dissertation aims to determine (i) whether reservoir hosts exist for Laf amongst indigenous rutaceous species that also act as native hosts to T. erytreae and (ii) whether LafC can be transmitted vertically through Ca. capense seeds. To achieve the first aim, a total of 234 Clausena anisata, 289 Vepris lanceolata and 231 Zanthoxylum capense specimens were assessed for the presence of Liberibacter by making use of a Liberibacter generic real-time PCR assay. Positive samples were further characterized by using a multi-gene phylgenetic approach based on the nucleotide sequences for the 16S, rplJ and omp genes, which respectively encode the 16S ribosomal RNA (rRNA) subunit, 50S ribosomal subunit protein L10 and the outer membrane protein. The tree host species from which Liberibacter sequences were obtained were DNA barcoded using standard procedures. Of the trees tested, 33 Cl. anisata, 17 V. lanceolata, 9 Z. capense and 1 Zanthoxylum davyi, tested positive for Liberibacter. Phylogenetic analysis of the rplJ and omp gene regions, revealed unique Liberibacter clusters associated with each tree species. Phylogenetic analysis of 16S data indicated that the strains detected in V. lanceolata and Cl. anisata were grouped with LafC, while those from Zanthoxylum species grouped separately. The presence of these bacteria in indigenous Rutaceous species should be further investigated to determine whether they are capable of being transmitted to and causing disease on commercial citrus species. To address the second aim of the study, seeds of Ca. capense were collected from two mother trees with known LafC infection. Following total DNA extraction from the midribs of leafs grown from these seeds, a LafC directed real-time PCR system was used to detect the bacterium. However, none of the samples had Ct values <35, the positive/negative threshold. From this study, no indication of seed-transmission was obtained within the limited number of samples which could be tested. The lack of vertical transmission of both Laf and LafC is seeminly a characteristic shared amongst African Liberibacter species.
机译：南非的绿化病与被称为“非洲假丝酵母”（Laf）的变形杆菌有限的韧皮部成员有关。该细菌的传播是通过其三唑类载体Trioza erytreae的飞行和进食活动来辅助的。除拉夫外，'Candidatus Liberibacter africanus亚种。已经从这个国家描述了capensis'（LafC）。 LafC与本土的芸苔属植物Calodendrum capense广泛相关。本文的目的是确定（i）在同样作为黑麦草的天然寄主的土生rutaceous物种中是否存在Laf的储层宿主，以及（ii）LafC是否可以通过Ca垂直传播。种子。为了实现第一个目标，通过使用利比里亚细菌通用实时PCR分析法对总共234例茴香芥，289头尖螺旋藻和231种花椒进行了评估。通过基于16S，rplJ和omp基因的核苷酸序列的多基因系统学方法进一步表征阳性样品，这些基因分别编码16S核糖体RNA（rRNA）亚基，50S核糖体亚基蛋白L10和外膜蛋白。使用标准程序对从其获得解放杆菌序列的树宿主物种进行DNA条形码编码。在测试的树木中，有33 Cl。 anisata，17 V. lanceolata，9 Z. capense和1 Zanthoxylum davyi对Liberibacter测试呈阳性。 rplJ和omp基因区域的系统发育分析，揭示了与每种树种相关的独特的Liberibacter簇。对16S数据的系统发育分析表明，在轮叶圆弧菌和Cl中检出了菌株。茴香与LafC分组，而花椒属的则分别分组。这些细菌在本地芸苔属物种中的存在应进一步调查，以确定它们是否能够传播至商业柑橘物种并引起其疾病。为了解决研究的第二个目标，钙的种子。从已知有LafC感染的两棵母树中收集了苯丙胺。从这些种子生长的叶片中脉中提取总DNA后，使用LafC指导的实时PCR系统检测细菌。但是，没有一个样品的Ct值小于35（正/负阈值）。从这项研究中，在可以测试的有限数量的样本中没有获得种子传播的迹象。 Laf和LafC都缺乏垂直传播，这似乎是非洲Liberibacter菌种共有的特征。

著录项

  • 作者

    Viljoen, Ronel.;

  • 作者单位

    University of Pretoria (South Africa).;

  • 授予单位 University of Pretoria (South Africa).;
  • 学科 Microbiology.;Plant sciences.
  • 学位 M.S.
  • 年度 2013
  • 页码 132 p.
  • 总页数 132
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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