Necchi Orlando, Oliveira Mariana Cabral
Zoology and Botany Department, São Paulo State University, Rua Cristóvão Colombo, 2265, 15054-000 São José do Rio Preto, São Paulo, BrazilBotany Department, São Paulo University, Rua do Matão, 277, 05508-900 São Paulo, São Paulo, Brazil.
J Phycol. 2011 Jun;47(3):680-686. doi: 10.1111/j.1529-8817.2011.00997.x. Epub 2011 May 9.
This study evaluated the phylogenetic relationship among samples of "Chantransia" stage of the Batrachospermales and Thoreales from several regions of the world based on sequences of two genes-the plastid-encoded RUBISCO LSU gene (rbcL) and the nuclear SSU ribosomal DNA gene (SSU rDNA). All sequences of "Chantransia macrospora" were shown to belong to Batrachospermum macrosporum based on both molecular markers, confirming evidence from previous studies. In contrast, nine species are now associated with "Chantransia pygmaea," including seven species of the Batrachospermales and two of the Thoreales. Therefore, the presence of "C. macrospora" in a stream can be considered reliable evidence that it belongs to B. macrosporum, whereas the occurrence of "C. pygmaea" does not allow the recognition of any particular species, since it is associated with at least nine species. Affinities of "Chantransia" stages to particular taxa were congruent for 70.5% of the samples comparing the rbcL and SSU analyses, which were associated with the same or closely related species for both markers. Sequence divergences have been reported in the "Chantransia" stage in comparison to the respective gametophyte, and this matter deserves further attention.
本研究基于两个基因的序列，即质体编码的核酮糖-1,5-二磷酸羧化酶大亚基基因（rbcL）和核糖体DNA小亚基基因（SSU rDNA），评估了来自世界几个地区的串珠藻目和索藻目的“串珠藻属”阶段样本之间的系统发育关系。基于这两种分子标记，所有“大孢串珠藻”的序列均显示属于大孢串珠藻，这证实了先前研究的证据。相比之下，现在有九个物种与“矮小串珠藻”相关联，其中包括七个串珠藻目物种和两个索藻目物种。因此，溪流中出现“大孢串珠藻”可被视为其属于大孢串珠藻的可靠证据，而“矮小串珠藻”的出现则无法识别任何特定物种，因为它与至少九个物种相关联。在比较rbcL和SSU分析时，70.5%的样本中“串珠藻属”阶段与特定分类群的亲缘关系是一致的，这两种标记都与相同或密切相关的物种相关联。与各自的配子体相比，“串珠藻属”阶段已报道存在序列差异，此事值得进一步关注。
