Brady Carrie, Arnold Dawn, McDonald James, Denman Sandra
Faculty of Health and Life Sciences, Centre for Research in Bioscience, University of the West of England, Frenchay Campus, Coldharbour Lane, Bristol, BS16 1QY, UK.
School of Biological Sciences, Bangor University, Bangor, Gwynedd, UK.
World J Microbiol Biotechnol. 2017 Jul;33(7):143. doi: 10.1007/s11274-017-2296-4. Epub 2017 Jun 16.
Acute oak decline (AOD) is a relatively newly described disorder affecting native oak species in Britain. Symptomatic trees are characterised by stem bleeds from vertical fissures, necrotic lesions in the live tissue beneath and larval galleries of the two spotted oak buprestid (Agrilus biguttatus). Several abiotic and biotic factors can be responsible for tree death, however the tissue necrosis and stem weeping is thought to be caused by a combination of bacterial species. Following investigations of the current episode of AOD which began in 2008, numerous strains belonging to several different bacteria in the family Enterobacteriaceae have been consistently isolated from symptomatic tissue. The majority of these enterobacteria were found to be novel species, subspecies and even genera, which have now been formally classified. The most frequently isolated species from symptomatic oak are Gibbsiella quercinecans, Brenneria goodwinii and Rahnella victoriana. Identification of these bacteria is difficult due to similarities in colony morphology, phenotypic profile and 16S rRNA gene sequences. Current identification relies heavily on gyrB gene amplification and sequencing, which is time consuming and laborious. However, newer techniques based on detection of single nucleotide polymorphisms show greater promise for rapid and reliable identification of the bacteria associated with AOD.
急性橡树衰退（AOD）是一种相对较新描述的影响英国本土橡树物种的病症。出现症状的树木的特征是从垂直裂缝处茎干出血、下方活组织中的坏死病变以及双斑橡木吉丁虫（Agrilus biguttatus）的幼虫蛀道。几种非生物和生物因素可能导致树木死亡，然而，组织坏死和茎干渗液被认为是由多种细菌共同作用引起的。在对始于2008年的当前这一波AOD疫情进行调查后，从出现症状的组织中持续分离出了许多属于肠杆菌科几种不同细菌的菌株。这些肠杆菌中的大多数被发现是新物种、亚种甚至新属，现在已被正式分类。从出现症状的橡树中最常分离出的物种是栎枯萎吉氏杆菌（Gibbsiella quercinecans）、古德温布伦纳氏菌（Brenneria goodwinii）和维克托利亚拉恩氏菌（Rahnella victoriana）。由于菌落形态、表型特征和16S rRNA基因序列相似，这些细菌的鉴定很困难。目前的鉴定严重依赖于gyrB基因扩增和测序，这既耗时又费力。然而，基于单核苷酸多态性检测的新技术在快速可靠地鉴定与AOD相关的细菌方面显示出更大的前景。
