Kolarčik Vladislav, Mirková Mária, Mikoláš Vlastimil
Institute of Biology and Ecology, Faculty of Science, Pavol Jozef Šafárik University, Mánesova 23, SK-041 54 Košice, Slovakia.
Independent Researcher, Hanojská 4, SK-040 13 Košice, Slovakia.
Plants (Basel). 2023 Jan 13;12(2):373. doi: 10.3390/plants12020373.
The remarkable species diversity of the genus is a result of polyploidization and frequent hybridization between interacting species of different cytotypes. Moreover, hybridization is possible between several parental taxa. Gametophytic apomixis, which is common among polyploid taxa, indicates the role of clonal reproduction in the evolutionary stabilization of hybridogeneous genotypes. The precise determination of the origin of seeds and their quantitative evaluation may elucidate inter-cytotype interactions, the potential role of mixed-cytotype populations in evolutionary success, and the long-term survival of some hybrid species. We investigated the reproduction modes of selected species of in mixed-cytotype populations in eastern Slovakia, Central Europe. We determined the pollen quality, seed production rate, and the ploidy level of mature trees, as well as the origin of the embryo and endosperm in seeds of the stenoendemics , , and . The tetraploids and are characterized by regular and highly stainable pollen grains and reproduce predominantly via pseudogamous apomixis. In contrast, triploid usually has oval, heterogenous, and weakly stainable pollen grains, suggesting male meiotic irregularities. Although seeds originate via pseudogamous apomixis in as well, the ploidy level of sperm cells participating in the fertilization of central cells is usually determined by co-occurring species of different cytotypes. This suggests that maintaining mating partners is necessary for the long-term survival of a triploid species. We documented rare B hybrids and the residual sexuality in tetraploids. The distribution of seeds of meiotic and apomeiotic origins in shows bimodal characteristics; however, genotypes with predominantly sexual seed types are rare. Reproduction modes documented in polyploid stenoendemics of and inferred microevolutionary intercytotype relationships highlight the mixed-cytotype populations as the source of biodiversity in apomictic plant complexes. We suggest that conservation efforts should focus on maintaining the species and cytotypic diversity of populations, especially when it comes to the conservation of triploid species.
该属显著的物种多样性是多倍体化以及不同细胞型的相互作用物种之间频繁杂交的结果。此外，几个亲本分类群之间也可能发生杂交。配子体无融合生殖在多倍体分类群中很常见，这表明克隆繁殖在杂交基因型的进化稳定中发挥了作用。种子起源的精确确定及其定量评估可能会阐明细胞型间的相互作用、混合细胞型种群在进化成功中的潜在作用以及一些杂交物种的长期生存情况。我们研究了中欧斯洛伐克东部混合细胞型种群中选定的分类群的繁殖模式。我们确定了成熟树木的花粉质量、种子生产率和倍性水平，以及狭域特有种、和种子中胚和胚乳的起源。四倍体和的特征是花粉粒规则且染色性强，主要通过假配性无融合生殖进行繁殖。相比之下，三倍体的花粉粒通常呈椭圆形、异质且染色性弱，表明雄性减数分裂存在异常。尽管在中种子也是通过假配性无融合生殖产生的，但参与中央细胞受精的精细胞的倍性水平通常由不同细胞型的共存物种决定。这表明维持交配伙伴对于三倍体物种的长期生存是必要的。我们记录了罕见的B杂交种和四倍体中的残余有性生殖现象。中减数分裂起源和无融合生殖起源种子的分布呈现双峰特征；然而，主要为有性种子类型的基因型很少见。在分类群的多倍体狭域特有种中记录的繁殖模式以及推断的微观进化细胞型间关系突出了混合细胞型种群是无融合生殖植物复合体生物多样性的来源。我们建议保护工作应侧重于维持分类群种群的物种和细胞型多样性，特别是在三倍体物种的保护方面。
