Loss of all plastid ndh genes in Gnetales and conifers: extent and evolutionary significance for the seed plant phylogeny
Loss of all plastid ndh genes in Gnetales and conifers: extent and evolutionary significance for the seed plant phylogeny
复制标题
DOI：
10.1007/s00294-009-0249-7
复制
发表时间：
2009-06-01
期刊：
影响因子：
2.5
通讯作者：
Stefanovic, Sasa
中科院分区：
文献类型：
--
作者：
Braukmann, Thomas Werner Anthony;Kuzmina, Maria;Stefanovic, Sasa
买麻藤目是裸子植物中一个小的高度变异的类群，其分子进化速度加快，其系统发育位置的确定是种子植物系统学中最具挑战性的问题之一。最近的结果，从整个质体基因组（ptDNA）测序显示的情况下，整个套件的质体ndh基因在几个物种的买麻藤和松树科（松科）可能突出了一个主要的结构特征，连接这两个群体的所有质体基因的NADH脱氢酶复合物的一致损失。然而，裸子植物ndh基因丢失的精确程度还没有调查。利用狭缝杂交技术，对85个裸子植物属中70个属的162种植物的11个ndh基因进行了检测。我们发现所有的ndh基因在买麻藤目和松科中都不存在，但在裸子植物的任何其他组中都不存在。这一特征代表了由这两个谱系组成的进化枝的主要突触形态，或者不太可能是收敛损失。我们的调查大大扩展了以前的推论的基础上更有限的抽样，如果前进化的解释是正确的，它提供了额外的支持有争议的“gnepine”的假设，这地方买麻藤作为姐妹松科。
The exact phylogenetic position of Gnetales, a small, highly modified group of gymnosperms with an accelerated rate of molecular evolution, is one of the most challenging issues for seed plant systematics. Recent results from entire plastid genome (ptDNA) sequencing revealed the absence of the entire suite of plastid ndh genes in several species of Gnetales and the pine family (Pinaceae) potentially highlighting a major structural feature linking these two groups-concerted loss of all plastid genes for the NADH dehydrogenase complex. However, the precise extent of ndh gene loss in gymnosperms has not been surveyed. Using a slot-blot hybridization method, we probed all 11 ndh genes in 162 species from 70 of 85 gymnosperm genera. We find that all ndh genes are absent across Gnetales and Pinaceae, but not in any other group of gymnosperms. This feature represents either a major synapomorphy for a clade consisting of these two lineages or, less likely, a convergent loss. Our survey substantially extends previous inferences based on more limited sampling and, if the former evolutionary interpretation is correct, it provides additional support for the contentious "gnepine" hypothesis, which places Gnetales as sister to Pinaceae.