Diversity of endophytic bacterial populations and their interaction with Xylella fastidiosa in citrus plants
Diversity of endophytic bacterial populations and their interaction with Xylella fastidiosa in citrus plants
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DOI：
10.1128/aem.68.10.4906-4914.2002
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发表时间：
2002-10-01
影响因子：
4.4
通讯作者：
Azevedo, JL
中科院分区：
文献类型：
--
作者：
Araújo, WL;Marcon, J;Azevedo, JL
柑桔杂色褪绿病（Citrus variegated chlorosis，CVC）是由苛养木杆菌（Xylella fastidiosa）引起的一种植物病原细菌，可侵染所有的柑桔品种。通过培养和非培养技术研究了健康、抗性和受CVC影响的柑橘植物的内生细菌群落。采用平板培养和变性梯度凝胶电泳（DGGE）技术，对表面消毒处理后的柑橘枝条内生真菌群落进行了研究。通过脂肪酸甲酯分析，鉴定出优势菌株为短小芽孢杆菌、软化短杆菌、阴沟肠杆菌、甲基杆菌。（包括扭脱甲基杆菌（Methylobacterium extorquens）、M. fujisawaense，M. mesophilicum，M. radiotolerans和M. zatmanii），诺卡氏菌属，成团泛菌和野油菜黄单胞菌。我们观察到CVC症状与甲基杆菌属物种分离频率之间的关系，甲基杆菌属是我们最常从有症状的植物中分离的属。相比之下，我们从无症状植物中比从具有CVC症状的那些植物中显著更频繁地分离出柔枝假单胞菌，而成团假单胞菌经常从柑橘（Citrus reticulata）和甜橙（Citrus reticulata）分离。sinensis）植物，无论植物是否有症状或无症状或显示CVC的症状。DGGE分析16S rRNA基因片段的扩增从总的植物DNA中产生的几个条带匹配的细菌分离物，表明DGGE图谱可以用来检测一些内生细菌的柑橘植物。然而，有些带与任何分离物都不匹配，表明存在其他不可培养或尚未培养的内生细菌。只有在无症状植株中才观察到一条G+C比值高的特异带。无症状植物中更高频率的柔枝梭菌表明该生物体在植物对CVC的抗性中的作用。
Citrus variegated chlorosis (CVC) is caused by Xylella fastidiosa, a phytopathogenic bacterium that can infect all Citrus sinensis cultivars. The endophytic bacterial communities of healthy, resistant, and CVC-affected citrus plants were studied by using cultivation as well as cultivation-independent techniques. The endophytic communities were assessed in surface-disinfected citrus branches by plating and denaturing gradient gel electrophoresis (DGGE). Dominant isolates were characterized by fatty-acid methyl ester analysis as Bacillus pumilus, Curtobacterium flaccumfaciens, Enterobacter cloacae, Methylobacterium spp. (including Methylobacterium extorquens, M. fujisawaense, M. mesophilicum, M. radiotolerans, and M. zatmanii), Nocardia sp., Pantoea agglomerans, and Xanthomonas campestris. We observed a relationship between CVC symptoms and the frequency of isolation of species of Methylobacterium, the genus that we most frequently isolated from symptomatic plants. In contrast, we isolated C.flaccumfaciens significantly more frequently from asymptomatic plants than from those with symptoms of CVC while P. agglomerans was frequently isolated from tangerine (Citrus reticulata) and sweet-orange (C. sinensis) plants, irrespective of whether the plants were symptomatic or asymptomatic or showed symptoms of CVC. DGGE analysis of 16S rRNA gene fragments amplified from total plant DNA resulted in several bands that matched those from the bacterial isolates, indicating that DGGE profiles can be used to detect some endophytic bacteria of citrus plants. However, some bands had no match with any isolate, suggesting the occurrence of other, nonculturable or as yet uncultured, endophytic bacteria. A specific band with a high G+C ratio was observed only in asymptomatic plants. The higher frequency of C.flaccumfaciens in asymptomatic plants suggests a role for this organism in the resistance of plants to CVC.