松材线虫侵染对马尾松苗不同部位内生细菌菌群结构的影响

  目的  探究松材线虫Bursaphelenchus xylophilus侵染下松干、松针与根系部位内生细菌菌群的结构变化，可充分挖掘马尾松Pinus massoniana内生细菌资源。  方法  采用变性梯度凝胶电泳(DGGE)及高通量测序技术，对松材线虫侵染下3年生马尾松不同部位内生细菌的结构多样性进行分析。  结果  ①马尾松不同部位内生细菌菌群结构存在较大差异，菌群多样性从大到小依次为松干、松针、根系。②松干部位部分细菌属在侵染15 d时丰度明显增加，但苗木表面并不表现任何症状。③马尾松体内共检测到内生细菌442属，分属35门49纲110目210科。其中松干与松针部位的甲基杆菌属Methylobacterium、假平胞菌属Sphingomonas、薄层菌属Hymenobacter、泛菌属Pantoea、假单胞菌属Sphingomonas与短小杆菌属Curtobacterium在侵染过程中相对丰度变化较大。  结论  松材线虫侵染下，马尾松根部基本不受影响，但松干部位内生细菌菌群结构变化极显著，其次是松针。部分内生细菌可能对松材线虫病具有潜在生防效果，有助于后期生防菌株的挖掘。在侵染高峰期实时监测干部内生细菌菌群结构变化，有助于松材线虫病的早期诊断。图5表1参25

Effect of Bursaphelenchus xylophilus infection on the endophytic bacterial community structure in different parts of Pinus massoniana seedlings

  Objective  With an investigation of the structural changes of the endophytic bacterialflora of pine stems, pine needles and pine roots, this study is aimed to fully explore the endophytic bacterial resources of Pinus massoniana.  Method  DGGE and high-throughput sequencing technology was employed in the exploration of the structural changes of endophyticbacterial flora of three-year-old P. massoniana trees upon the infection of Bursaphelenchus xylophilus disease.  Result  (1) There was a significant diversity in the endophytic bacterial community structure in different parts of P. massoniana trees with the diversity decreasing from the pine stem to pine needles and to the root system. (2) There was significant increase in parts of the bacterial genera in pine stems after 15 days of infection, whereas there were no symptoms shown on the surface of the seedlings. (3) Of the 442 genera of endophytic bacteria detected in P. massoniana that fall into 35 phyla, 49 classes, 110 order and 210 families, the relative abundance of Methylobacterium, Sphingomonas, Hymenobacter, Pantoea, Sphingomonas and Curtobacterium in pine stems and pine needles varies greatly throughout the infection process.  Conclusion  The effect of the infection of B. xylophilus disease on the structure of the endophytic bacterial flora varies from none to pretty significant to extremely significant in roots, pine needles and pine stems respectively. And some endophytic bacteria may have potential biocontrol effects on B. xylophilus disease, which is conducive to the excavation of later biocontrol strains. In addition, real-time monitoring of changes in the bacterial community structure of pine stems during the peak period of infection is helpful to the early diagnosis of B. xylophilus disease. Ch, 5 fig. 1 tab. 25 ref.]