Complex patterns of ploidy in a holocentric plant clade (Schoenus, Cyperaceae) in the Cape biodiversity hotspot
Complex patterns of ploidy in a holocentric plant clade (Schoenus, Cyperaceae) in the Cape biodiversity hotspot
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DOI：
10.1093/aob/mcac027
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发表时间：
2022-04-27
期刊：
影响因子：
4.2
通讯作者：
Bures, Petr
中科院分区：
文献类型：
--
作者：
Elliott, Tammy L.;Muasya, Muthama;Bures, Petr
背景和目的目前还不清楚多倍体在最大的全着丝粒植物家族-莎草科中的分布有多广。由于染色体融合和分裂的普遍性，其影响染色体数目但不影响基因组大小，因此仅基于染色体计数数据可能无法区分个体植物是否为全着丝粒谱系中的多倍体。此外，目前还不清楚基因组大小和倍性水平的差异如何与全着丝粒谱系（如莎草科）内的环境相关。方法我们集中我们的分析部落Schoeneae，更具体地说，南部非洲的Schoenus分支。我们研究了大规模的模式，在部落Schoeneae的基因组大小的演变，并更强烈地集中在确定整个南部非洲Schoenus的多倍体的患病率推断倍性水平与程序ChromEvol，以及解释染色体数目和基因组大小的数据。我们进一步调查是否有基因组大小/倍性水平和环境变量之间的关系，在营养不良和夏季干旱的开普生物多样性热点。关键结果我们的结果显示，与Schoeneae部落的其他物种相比，Schoenus的基因组大小大幅增加，但染色体数量没有增加。在Schoenus中，染色体数目和基因组大小之间存在正相关关系，我们的研究结果表明，多倍性是整个南部非洲Schoenus的一个相对常见的过程。在区域尺度的好望角，我们发现，多倍体更经常与干燥的位置，有更多的变化，降水之间的干燥和潮湿的月份，但这些结果是敏感的倍性水平的分类。结论多倍体在南部非洲Schoenus中较为常见，染色体数目与基因组大小呈正相关。因此，全中心植物中多倍性的发生率可能很高，其细胞分裂特性与单中心植物不同。
Background and Aims It is unclear how widespread polyploidy is throughout the largest holocentric plant family - the Cyperaceae. Because of the prevalence of chromosomal fusions and fissions, which affect chromosome number but not genome size, it can be impossible to distinguish if individual plants are polyploids in holocentric lineages based on chromosome count data alone. Furthermore, it is unclear how differences in genome size and ploidy levels relate to environmental correlates within holocentric lineages, such as the Cyperaceae. Methods We focus our analyses on tribe Schoeneae, and more specifically the southern African clade of Schoenus. We examine broad-scale patterns of genome size evolution in tribe Schoeneae and focus more intensely on determining the prevalence of polyploidy across the southern African Schoenus by inferring ploidy level with the program ChromEvol, as well as interpreting chromosome number and genome size data. We further investigate whether there are relationships between genome size/ploidy level and environmental variables across the nutrient-poor and summer-arid Cape biodiversity hotspot. Key Results Our results show a large increase in genome size, but not chromosome number, within Schoenus compared to other species in tribe Schoeneae. Across Schoenus, there is a positive relationship between chromosome number and genome size, and our results suggest that polyploidy is a relatively common process throughout the southern African Schoenus. At the regional scale of the Cape, we show that polyploids are more often associated with drier locations that have more variation in precipitation between dry and wet months, but these results are sensitive to the classification of ploidy level. Conclusions Polyploidy is relatively common in the southern African Schoenus, where a positive relationship is observed between chromosome number and genome size. Thus, there may be a high incidence of polyploidy in holocentric plants, whose cell division properties differ from monocentrics.