Fu Weirui, Liu Xiaoqing, Zhang Naixin, Song Zhiping, Zhang Wenju, Yang Ji, Wang Yuguo
Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Sciences, Institute of Biodiversity Science, Fudan UniversityShanghai, China.
Front Plant Sci. 2017 Aug 15;8:1380. doi: 10.3389/fpls.2017.01380. eCollection 2017.
Orobanchaceae is the largest family among the parasitic angiosperms. It comprises non-parasites, hemi- and holoparasites, making this family an ideal test case for studying the evolution of parasitism. Previous phylogenetic analyses showed that holoparasitism had arisen at least three times from the hemiparasitic taxa in Orobanchaceae. Until now, however, not all known genera of Orobanchaceae were investigated in detail. Among them, the unknown phylogenetic positions of the holoparasites and are the key to testing how many times holoparasitism evolved. Here, we provide clear evidence for the first time that they are members of the tribe Orobancheae, using sequence data from multiple loci (nuclear genes ITS, , and plastid genes K). is an independent lineage whereas should be merged into genus section . Our results unambiguously support the hypothesis that there are only three origins of holoparasitism in Orobanchaceae. Divergence dating reveals for the first time that the three origins of holoparasitism were not synchronous. Our findings suggest that holoparasitism can persist in specific clades for a long time and holoparasitism may evolve independently as an adaptation to certain hosts.
列当科是寄生被子植物中最大的科。它包括非寄生植物、半寄生植物和全寄生植物，这使得该科成为研究寄生现象进化的理想案例。先前的系统发育分析表明，全寄生现象在列当科中至少从半寄生类群中独立出现过三次。然而，直到现在，并非所有已知的列当科属都得到了详细研究。其中，全寄生植物和的未知系统发育位置是检验全寄生现象进化了多少次的关键。在这里，我们首次利用多个基因座（核基因ITS、和叶绿体基因K）的序列数据，明确证明它们是列当属的成员。是一个独立的谱系，而应并入属组。我们的结果明确支持了列当科中全寄生现象只有三个起源的假说。分歧时间估计首次揭示全寄生现象的三个起源并非同步。我们的研究结果表明，全寄生现象可以在特定的分支中持续很长时间，并且全寄生现象可能作为对某些宿主的一种适应而独立进化。
