Tkach Natalia, Nobis Marcin, Schneider Julia, Becher Hannes, Winterfeld Grit, Jacobs Surrey W L, Röser Martin
Department of Systematic Botany, Institute of Biology, Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Halle (Salle), Germany.
Institute of Botany, Faculty of Biology, Jagiellonian University, Kraków, Poland.
Front Plant Sci. 2021 Jan 22;11:630788. doi: 10.3389/fpls.2020.630788. eCollection 2020.
The mainly Australian grass genus (tribe Stipeae) comprising approximately 64 species represents a remarkable example of an evolutionary radiation. To investigate aspects of diversification, macro- and micromorphological variation in this genus, we conducted molecular phylogenetic and scanning electron microscopy (SEM) analyses including representatives from most of 's currently accepted subgenera. Because of its taxonomic significance in Stipeae, we studied the lemma epidermal pattern (LEP) in 34 representatives of Plastid DNA variation within was low and only few lineages were resolved. Nuclear ITS and yielded comparable groupings of taxa and resolved subgenera , , and in a common clade and as monophyletic. In most of the species studied, the LEP was relatively uniform (typical maize-like), but six species had a modified cellular structure. The species representing subgenera , , as well as from subg. were well-separated from all the other species included in the analysis. We suggest recognizing nine subgenera in (with number of species): (4), (2), (36), (2), (10), (5), (2), (2) and the new subgenus (1) encompassing . Two paralogous sequence copies of , forming two distinct clades, were found in polyploid and . We found analogous patterns for our samples of s.str. with their clades strongly separated from those of and . This underlines a previous hypothesis of Tzvelev (1977) that most extant Stipeae are of hybrid origin. We also prepared an up-to-date survey and reviewed the chromosome number variation for our molecularly studied taxa and the whole tribe Stipeae. The chromosome base number patterns as well as dysploidy and whole-genome duplication events were interpreted in a phylogenetic framework. The rather coherent picture of chromosome number variation underlines the enormous phylogenetic and evolutionary significance of this frequently ignored character.
主要分布于澳大利亚的禾本科属（针茅族）包含约64个物种，是进化辐射的一个显著例子。为了研究该属的多样化、宏观和微观形态变异，我们进行了分子系统发育分析和扫描电子显微镜（SEM）分析，其中包括来自该属目前大多数公认亚属的代表。由于其在针茅族中的分类学意义，我们研究了34个代表物种的外稃表皮模式（LEP）。该属内的质体DNA变异较低，仅解析出少数几个谱系。核ITS和其他基因产生了可比的分类群分组，并将亚属、和解析为一个共同的分支且为单系。在大多数研究的该属物种中，LEP相对一致（典型的玉米状），但有六个物种具有改良的细胞结构。代表亚属、以及亚属的物种与分析中包含的所有其他物种明显分开。我们建议在该属中识别出九个亚属（物种数量）：（4个）、（2个）、（36个）、（2个）、（10个）、（5个）、（2个）、（2个）和新亚属（1个），包括。在多倍体和中发现了的两个旁系同源序列拷贝，形成了两个不同的分支。我们在该属狭义样本中发现了类似的模式，其分支与和的分支强烈分开。这强调了Tzvelev（1977）之前的一个假设，即大多数现存的针茅族是杂交起源的。我们还进行了最新的调查，并回顾了我们分子研究的分类群以及整个针茅族的染色体数目变异。在系统发育框架中解释了染色体基数模式以及非整倍体和全基因组复制事件。染色体数目变异相当连贯的情况强调了这个经常被忽视的特征在系统发育和进化方面的巨大意义。
