科研之友
微信
新浪微博
Facebook
分享链接
摘要
Lettuce plants showing symptoms of lettuce big-vein disease were collected from fields in the Perth Metropolitan region of southwest Australia When root extracts from each plant were tested by polymerase chain reaction (PCR) using primers specific to the rDNA internal transcribed spacer (ITS) legion of Olpidium brassicae and O virulentus. only O vitamins was detected in each of them The nucleotide sequences of the complete rDNA ITS legions of isolates from five of the root samples and 10 isolates of O virulentus from Europe and Japan showed 97 9 to 100% identities However. with the six O brassicae isolates. then identities were only 76 9 to 79 4% On phylogenetic analysis of the complete rDNA-ITS region sequences of the five Australian isolates and 10 others. the Australian isolates fitted within two clades of O virulentus (I and II). and within clade I into two of its four subclades (Ia and Id) Japanese isolates had greatest sequence diversity fitting into both chides and into all of clade 1 subclades except Ib. while European isolates were restricted to subclades Ib and Id When the partial rDNA-ITS region sequences of two additional southwest Australian isolates, four from Europe. and four from the Americas were included in the analyses. the Australian isolates were within O. virulentus subclades la and Id. the European isolates within subclade Ic. and the American isolates wit hut subclades Ia and Ib These findings suggest that there may have been at least three separate introductions of O wildcat's into the isolated Australian continent since plant cultivation was introduced following its colonization by Europeans They also have implications regarding numbers of different introductions to other isolated regions Lettuce big-vein associated virus and Mirafiori lettuce big-vein virus were both detected when symptomatic lettuce leaf tissue samples corresponding to the root samples from southwest Australia were tested using virus-specific primers in reverse transcription PCR. so presence of both viruses was associated with O wildcat's occurrence
- 出版日期2010-5
