Feng Chao, Wang Jing, Wu Lingqing, Kong Hanghui, Yang Lihua, Feng Chen, Wang Kai, Rausher Mark, Kang Ming
Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
Novogene Bioinformatics Institute, Beijing, 100083, China.
New Phytol. 2020 Aug;227(4):1249-1263. doi: 10.1111/nph.16588. Epub 2020 May 14.
Although whole genome duplication (WGD) has been suggested to facilitate adaptive evolution and diversification, the role of specific WGD events in promoting diversification and adaptation in angiosperms remains poorly understood. Primulina, a species-rich genus with > 180 species associated with limestone karst habitat, constitutes an ideal system for studying the impact of WGD events on speciation and evolutionary adaptation. We sequenced and assembled a chromosome-level genome of the cave-dwelling species P. huaijiensis to study gene family expansion and gene retention following WGDs. We provide evidence that P. huaijiensis has undergone two WGDs since the γ triplication event shared by all eudicots. In addition to a WGD shared by almost all Lamiales (L event), we identified a lineage-specific WGD (D event) that occurred in the early Miocene around 20.6-24.2 Myr ago and that is shared by almost the entire subtribe Didymocarpinae. We found that gene retentions following the D event led to gene family proliferation (e.g. WRKYs) that probably facilitated adaptation to the high salinity and drought stress in limestone karst. Our study highlights the role of lineage-specific WGD in species diversification and adaptation of plants from special habitats.
尽管全基因组复制（WGD）被认为有助于适应性进化和多样化，但特定WGD事件在促进被子植物多样化和适应方面的作用仍知之甚少。报春苣苔属是一个物种丰富的属，有超过180种与石灰岩喀斯特生境相关，是研究WGD事件对物种形成和进化适应影响的理想系统。我们对洞穴居住物种怀集报春苣苔的染色体水平基因组进行了测序和组装，以研究WGD后的基因家族扩张和基因保留情况。我们提供的证据表明，自所有真双子叶植物共享的γ三倍化事件以来，怀集报春苣苔经历了两次WGD。除了几乎所有唇形目植物共享的一次WGD（L事件）外，我们还确定了一次谱系特异性WGD（D事件），该事件发生在约2060 - 2420万年前的中新世早期，几乎整个长蒴苣苔亚族都有发生。我们发现，D事件后的基因保留导致了基因家族的增殖（如WRKY基因家族），这可能促进了对石灰岩喀斯特高盐度和干旱胁迫的适应。我们的研究突出了谱系特异性WGD在特殊生境植物物种多样化和适应中的作用。
