Key message

We found a correlation between large pollens and selfing and between psilate pollen walls and cleistogamy.

Abstract

Flowering plants display extraordinary diversity in pollen morphology, yet the functional significance of this variation is not well understood. Zygophylloideae is a lineage characterized by high diversity of breeding systems, ranging from obligate selfing to facultative selfing and further to facultative outcrossing. This group is particularly suitable for testing hypotheses about the influence of breeding system on pollen morphology. We studied pollen morphology in 20 species of Zygophylloideae and one species of Tribuloideae as an outgroup. A phylogeny of Zygophylloideae was created based on available DNA sequences and used to trace the evolution of pollen characters. We performed a phylogenetic analysis of correlated evolution between breeding system and several pollen characters. Three types of pollen morphology were found in the studied species. Tricolporate pollen with a small apocolpium, microreticulate ornamentation and medium size was determined as the ancestral state in Zygophylloideae. The correlation analysis indicated an association between large pollens and selfing and between psilate pollen wall and cleistogamy. We hypothesize that large size of pollen in selfing species is mainly associated with the low number of produced pollen indicating a trade-off between pollen size and number. The independence from pollen vector in cleistogamous flowers accounts for the evolution of smooth pollen walls in these species.

中文翻译：

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繁殖系统会影响花粉形态吗？霸王科的一个案例研究。

关键信息

我们发现大花粉与自交之间，以及普拉提花粉壁与清除异型之间存在相关性。

抽象

开花植物在花粉形态上显示出非同寻常的多样性，但是这种变化的功能意义尚未得到很好的理解。霸王亚科是一系，其特征是繁殖系统的多样性很高，从专性自交到兼性自交，再到兼性异型交配。该小组特别适合检验关于繁殖系统对花粉形态的影响的假设。我们研究了20种Zygophylloideide科和一种Tribuloideae科的花粉形态。基于可用的DNA序列创建了Zygophylloideae的系统发育史，并用于追踪花粉特征的演变。我们对育种系统和一些花粉特性之间的相关进化进行了系统发育分析。在所研究的物种中发现了三种类型的花粉形态。在小叶藻科中，具有小顶杆，小网状装饰和中等大小的三colporate花粉被确定为祖先状态。相关性分析表明，大花粉与自交之间以及psilate花粉壁与清除性配子之间存在关联。我们假设自交物种中较大的花粉主要与产生的花粉数量少有关，表明花粉大小和数量之间存在权衡。杂种花朵中花粉载体的独立性解释了这些物种中光滑花粉壁的演变。相关性分析表明，大花粉与自交之间以及psilate花粉壁与清除性配子之间存在关联。我们假设自交物种中较大的花粉主要与产生的花粉数量少有关，表明花粉大小和数量之间存在折衷。杂种花朵中花粉载体的独立性解释了这些物种中光滑花粉壁的演变。相关性分析表明，大花粉与自交之间以及psilate花粉壁与清除性配子之间存在关联。我们假设自交物种中较大的花粉主要与产生的花粉数量少有关，表明花粉大小和数量之间存在权衡。杂种花朵中花粉载体的独立性解释了这些物种中光滑花粉壁的演变。