Ministry of Education Key Laboratory of Biodiversity Sciences and Ecological Engineering and State Key Laboratory of Genetic Engineering, Institute of Biodiversity Sciences and Institute of Plant Biology, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai 200438, China.
Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain, Guangxi Institute of Botany, Guangxi Zhuangzu Autonomous Region and Chinese Academy of Sciences, Guilin 541006, China.
Mol Plant. 2020 Aug 3;13(8):1117-1133. doi: 10.1016/j.molp.2020.05.011. Epub 2020 May 20.
The ability of climbing plants to grow upward along others to reach the canopy for photosynthesis is hypothesized as a key innovation in flowering plants. Most members of the Cucurbitaceae, a family containing ∼1000 species and many important crops, are climbers and have characteristic tendrils and pepo fruits. Here, we present 127 newly sequenced transcriptomes and genomes along with other datasets for a total of 136 cucurbits representing all tribes to establish a robust Cucurbitaceae phylogeny containing eight highly resolved major clades. We analyzed whole-genome duplication, diversification dynamics, and ancestral morphologies, and found that after early genome duplication event(s), a burst of diversification and morphological innovations in flower, fruit, and root characters occurred under the climate optimum in the Early Eocene. Species radiation during the Mid-Eocene Climatic Optimum also coincided with several morphological changes shared by 80% of cucurbits. We found that the cucurbit-specific tendril identity gene TEN originated from a paleo-polyploidization event at the origin of the family. Our results support the hypothesis that cucurbit diversifications were probably driven by increased genetic diversity following polyploidizations and by trait morphological innovations under paleo-climate upheavals. Our study provides a phylogenetic framework and new insights into morphological and genomic changes underlying the adaptive evolution of Cucurbitaceae.
攀缘植物能够沿着其他植物向上生长以到达冠层进行光合作用，这被假设为开花植物的一个关键创新。葫芦科包含约 1000 个物种和许多重要的作物，大多数成员都是攀缘植物，具有特征性的卷须和 pepo 果实。在这里，我们提供了 127 个新测序的转录组和基因组，以及其他 136 个葫芦科数据集，代表了所有的部落，以建立一个稳健的葫芦科系统发育，其中包含 8 个高度解析的主要分支。我们分析了全基因组复制、多样化动态和祖先形态，发现早期的基因组复制事件发生后，在早始新世的气候最佳时期，花、果和根特征发生了多样化和形态创新的爆发。中始新世气候最佳时期的物种辐射也与 80%的葫芦科共享的几个形态变化相吻合。我们发现，葫芦科特有的卷须识别基因 TEN 起源于家族起源时的古多倍体化事件。我们的研究结果支持这样一种假设，即葫芦科的多样化可能是由多倍体化后遗传多样性的增加以及古气候剧变下形态特征的创新所驱动的。我们的研究为葫芦科适应性进化的形态和基因组变化提供了一个系统发育框架和新的见解。
