Zhong Yuan, Du Ming-Jie, Ji Run-Ze, Cheng Fang-Yun
State Key Laboratory of Efficient Production of Forest Resources, National Engineering Research Center for Floriculture, Peony International Institute, School of Landscape Architecture, Beijing Forestry University, Beijing, China.
Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture, Peony International Institute, School of Landscape Architecture, Beijing Forestry University, Beijing, China.
Front Plant Sci. 2025 May 12;16:1586225. doi: 10.3389/fpls.2025.1586225. eCollection 2025.
Polyploidization is not only an important driving force for plant speciation and evolution, but also an effective approach for plant domestication and improvement. Polyploid taxa are quite common in section (herbaceous peonies), but very rare in section (tree peonies), which are known as the 'king of flowers'.
In this paper, we studied the origination of a tetraploid tree peony, 'Golden Era' ('GE', AABB), by comparing its karyotype with its seed parent, 'Golden Isles' ('GI', AB), based on genomic hybridization (GISH) and rDNA fluorescence hybridization (FISH). The meiosis behaviors of 'GI' were observed to make clear the cytogenetic process of unreduced (2) gamete generation.
Four chromosomes with inter-genome translocations were identified in 'GE', two of which might be reciprocal translocations. The 2 female gametes first division restitution (FDR) from 'GI' might play an important role in tetraploidization of 'GE'.
The distant hybridization between intersterile species from different subsections of section probably promotes the tetraploidization of tree peonies by facilitating 2 gamete production. The mechanism of tetraploidization in section is highly consistent with that in section , but is inseparable with the assist from mankind. The divergence of life history between tree peonies and herbaceous peonies is speculated to contribute to the different level of polyploidization, and distinct tempo of speciation and evolution, between section and section in genus . These findings bring new insights to polyploid breeding, speciation and evolution in genus .
多倍体化不仅是植物物种形成和进化的重要驱动力，也是植物驯化和改良的有效途径。多倍体类群在芍药组（草本芍药）中很常见，但在被誉为“花中之王”的牡丹组（木本芍药）中却非常罕见。
本文通过基于基因组原位杂交（GISH）和核糖体DNA荧光原位杂交（FISH），将四倍体牡丹‘金辉’（‘GE’，AABB）与其种子亲本‘金岛’（‘GI’，AB）的核型进行比较，研究了其起源。观察了‘GI’的减数分裂行为，以明确未减数（2n）配子产生的细胞遗传学过程。
在‘GE’中鉴定出4条具有基因组间易位的染色体，其中2条可能是相互易位。来自‘GI’的2n雌配子第一次分裂 restitution（FDR）可能在‘GE’的四倍体化过程中起重要作用。
牡丹组不同亚组间不育物种的远缘杂交可能通过促进2n配子产生来推动木本芍药的四倍体化。牡丹组的四倍体化机制与芍药组高度一致，但离不开人类的协助。推测木本芍药和草本芍药生活史的差异导致了芍药属牡丹组和芍药组在多倍体化水平、物种形成和进化速度上的不同。这些发现为芍药属的多倍体育种、物种形成和进化带来了新的见解。
