Kaplan D T, Thomas W K, Frisse L M, Sarah J L, Stanton J M, Speijer P R, Marin D H, Opperman C H
J Nematol. 2000 Jun;32(2):134-42.
The nucleic acid sequences of rDNA ITS1 and the rDNA D2/D3 expansion segment were compared for 57 burrowing nematode isolates collected from Australia, Cameroon, Central America, Cuba, Dominican Republic, Florida, Guadeloupe, Hawaii, Nigeria, Honduras, Indonesia, Ivory Coast, Puerto Rico, South Africa, and Uganda. Of the 57 isolates, 55 were morphologically similar to Radopholus similis and seven were citrus-parasitic. The nucleic acid sequences for PCR-amplified ITS1 and for the D2/D3 expansion segment of the 28S rDNA gene were each identical for all putative R. similis. Sequence divergence for both the ITS1 and the D2/D3 was concordant with morphological differences that distinguish R. similis from other burrowing nematode species. This result substantiates previous observations that the R. similis genome is highly conserved across geographic regions. Autapomorphies that would delimit phylogenetic lineages of non-citrus-parasitic R. similis from those that parasitize citrus were not observed. The data presented herein support the concept that R. similis is comprised of two pathotypes-one that parasitizes citrus and one that does not.
对从澳大利亚、喀麦隆、中美洲、古巴、多米尼加共和国、佛罗里达州、瓜德罗普岛、夏威夷、尼日利亚、洪都拉斯、印度尼西亚、科特迪瓦、波多黎各、南非和乌干达采集的57个穿孔线虫分离株的rDNA ITS1核酸序列和rDNA D2/D3扩展片段进行了比较。在这57个分离株中，55个在形态上与相似穿孔线虫相似，7个是寄生于柑橘的。所有假定的相似穿孔线虫的PCR扩增ITS1核酸序列和28S rDNA基因的D2/D3扩展片段的核酸序列均各自相同。ITS1和D2/D3的序列差异与区分相似穿孔线虫与其他穿孔线虫物种的形态差异一致。这一结果证实了先前的观察结果，即相似穿孔线虫的基因组在不同地理区域高度保守。未观察到能将非柑橘寄生型相似穿孔线虫的系统发育谱系与寄生柑橘的谱系区分开来的自近裔性状。本文提供的数据支持相似穿孔线虫由两种致病型组成的概念，一种寄生于柑橘，另一种不寄生于柑橘。
