Sundin G W, Demezas D H, Bender C L
Department of Plant Pathology, Oklahoma State University, Stillwater 74078.
Appl Environ Microbiol. 1994 Dec;60(12):4421-31. doi: 10.1128/aem.60.12.4421-4431.1994.
We examined the genetic and plasmid diversity within natural populations of Pseudomonas syringae isolated from three ornamental pear nurseries in eastern Oklahoma. The bactericide spray regimen differed at each nursery; copper and streptomycin, only copper, and no bactericides were applied at nurseries I, II, and III respectively. Resistance to copper (Cur) and resistance to streptomycin (Smr) were determined for 1,938 isolates of P. syringae; isolates from nurseries I and II were generally Cur Sms; whereas most isolates from nursery III were Cus Sms. The plasmid profiles of 362 isolates were determined, and six, one, seven, and four plasmid profiles were obtained for Cur, Smr, Cur Smr, and Cus Sms isolates, respectively. All Smr plasmids contained sequences homologous to the strA and strB Smr genes from broad-host-range plasmid RSF1010 and were associated with Smr transposon Tn5393. Plasmids were placed into two groups on the basis of hybridization to the oriV and par sequences from pOSU900, a cryptic plasmid in P. syringae pv. syringae. A total of 100 randomly chosen P. syringae isolates from nurseries I and III were analyzed for genetic diversity by using the arbitrarily primed PCR (AP-PCR) technique. An analysis of chromosomal genotypes by AP-PCR revealed a high degree of genetic diversity among the isolates, and the results of this analysis indicated that the isolates could be clustered into two distinct groups. The plasmid profiles were specific to isolates belonging to particular AP-PCR groups. Within each AP-PCR group, identical plasmid profiles were produced by isolates that had different chromosomal genotypes, implying that plasmid transfer has played an important role in the dissemination of Cur and Smr within the populations studied.
我们研究了从俄克拉荷马州东部三个观赏梨苗圃分离出的丁香假单胞菌自然种群中的遗传和质粒多样性。每个苗圃的杀菌剂喷洒方案不同；在苗圃I、II和III中分别施用了铜和链霉素、仅铜以及不施用任何杀菌剂。对1938株丁香假单胞菌进行了铜抗性（Cur）和链霉素抗性（Smr）测定；来自苗圃I和II的分离株通常为Cur Sms；而来自苗圃III的大多数分离株为Cus Sms。测定了362株分离株的质粒图谱，Cur、Smr、Cur Smr和Cus Sms分离株分别获得了六种、一种、七种和四种质粒图谱。所有Smr质粒都含有与来自广宿主范围质粒RSF1010的strA和strB Smr基因同源的序列，并与Smr转座子Tn5393相关。根据与丁香假单胞菌丁香致病变种中一个隐蔽质粒pOSU900的oriV和par序列杂交情况，将质粒分为两组。通过任意引物PCR（AP-PCR）技术对从苗圃I和III中随机选择的总共100株丁香假单胞菌分离株进行了遗传多样性分析。通过AP-PCR对染色体基因型的分析揭示了分离株之间高度的遗传多样性，该分析结果表明分离株可聚类为两个不同的组。质粒图谱特定于属于特定AP-PCR组的分离株。在每个AP-PCR组内，具有不同染色体基因型的分离株产生相同的质粒图谱，这意味着质粒转移在所研究的种群中Cur和Smr的传播中发挥了重要作用。
