Barionovi D, Giorgi S, Stoeger A R, Ruppitsch W, Scortichini M
C.R.A.-Istituto Sperimentale per la Frutticoltura, Ciampino Aeroporto, Rome, Italy.
J Appl Microbiol. 2006 May;100(5):1084-94. doi: 10.1111/j.1365-2672.2006.02813.x.
The three main aims of the study were the assessment of the genetic relationship between a deviating Erwinia amylovora strain isolated from Amelanchier sp. (Maloideae) grown in Canada and other strains from Maloideae and Rosoideae, the investigation of the variability of the PstI fragment of the pEA29 plasmid using restriction fragment length polymorphism (RFLP) analysis and the determination of the number of short-sequence DNA repeats (SSR) by DNA sequence analysis in representative strains.
Ninety-three strains obtained from 12 plant genera and different geographical locations were examined by repetitive-sequences PCR using Enterobacterial Repetitive Intergenic Consensus, BOX and Repetitive Extragenic Palindromic primer sets. Upon the unweighted pair group method with arithmetic mean analysis, a deviating strain from Amelanchier sp. was analysed using amplified ribosomal DNA restriction analysis (ARDRA) analysis and the sequencing of the 16S rDNA gene. This strain showed 99% similarity to other E. amylovora strains in the 16S gene and the same banding pattern with ARDRA. The RFLP analysis of pEA29 plasmid using MspI and Sau3A restriction enzymes showed a higher variability than that previously observed and no clear-cut grouping of the strains was possible. The number of SSR units reiterated two to 12 times. The strains obtained from pear orchards showing for the first time symptoms of fire blight had a low number of SSR units.
The strains from Maloideae exhibit a wider genetic variability than previously thought. The RFLP analysis of a fragment of the pEA29 plasmid would not seem a reliable method for typing E. amylovora strains. A low number of SSR units was observed with first epidemics of fire blight.
The current detection techniques are mainly based on the genetic similarities observed within the strains from the cultivated tree-fruit crops. For a more reliable detection of the fire blight pathogen also in wild and ornamentals Rosaceous plants the genetic features of deviating E. amylovora strains have to be studied in detail.
本研究的三个主要目的是评估从加拿大生长的唐棣属植物（苹果亚科）中分离出的一株偏离型梨火疫病菌株与苹果亚科和蔷薇亚科的其他菌株之间的遗传关系，使用限制性片段长度多态性（RFLP）分析研究pEA29质粒的PstI片段的变异性，并通过对代表性菌株进行DNA序列分析确定短序列DNA重复（SSR）的数量。
使用肠杆菌重复基因间共有序列（ERIC）、BOX和重复外显子回文序列（REP）引物组，通过重复序列PCR对从12个植物属和不同地理位置获得的93株菌株进行检测。采用算术平均非加权配对组法分析后，使用扩增核糖体DNA限制性分析（ARDRA）和16S rDNA基因测序对一株来自唐棣属植物的偏离型菌株进行分析。该菌株在16S基因中与其他梨火疫病菌株显示出99%的相似性，并且在ARDRA分析中具有相同的条带模式。使用MspI和Sau3A限制性内切酶对pEA29质粒进行RFLP分析显示，其变异性高于先前观察到的情况，并且无法对菌株进行明确分组。SSR单位的数量重复了2至12次。首次出现火疫病症状的梨园中获得的菌株SSR单位数量较少。
苹果亚科的菌株表现出比先前认为的更广泛的遗传变异性。对pEA29质粒片段进行RFLP分析似乎不是对梨火疫病菌株进行分型的可靠方法。在火疫病首次流行时观察到SSR单位数量较少。
目前的检测技术主要基于在栽培果树作物菌株中观察到的遗传相似性。为了更可靠地检测野生和观赏蔷薇科植物中的火疫病病原体，必须详细研究偏离型梨火疫病菌株的遗传特征。
