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Genomes of leafy and leafless Platanthera orchids illuminate the evolution of mycoheterotrophy

2022; Nature Portfolio; Volume: 8; Issue: 4 Linguagem: Inglês

10.1038/s41477-022-01127-9

2055-0278

Ming-He Li, Kewei Liu, Zhen Li, Hsiang-Chia Lu, Qin‐Liang Ye, Diyang Zhang, Jieyu Wang, Yufeng Li, Zhi‐Ming Zhong, Xuedie Liu, Xia Yu, Ding-Kun Liu, Xiong-De Tu, Bin Liu, Hao Yang, Xing‐Yu Liao, Yu-Ting Jiang, Weihong Sun, Jinliao Chen, Yanqiong Chen, Ye Ai, Junwen Zhai, Shasha Wu, Zhuang Zhou, Yu‐Yun Hsiao, Wan-Lin Wu, You‐Yi Chen, Yu-Fu Lin, Jui‐Ling Hsu, Chia‐Ying Li, Zhiwen Wang, Xiang Zhao, Wen-Ying Zhong, Xiaokai Ma, Liang Ma, Jie Huang, Gui-Zhen Chen, Ming‐Zhong Huang, Laiqiang Huang, Donghui Peng, Yi‐Bo Luo, Shuangquan Zou, Shipin Chen, Siren Lan, Wen‐Chieh Tsai, Yves Van de Peer, Zhong‐Jian Liu,

Plant Molecular Biology Research

Abstract To improve our understanding of the origin and evolution of mycoheterotrophic plants, we here present the chromosome-scale genome assemblies of two sibling orchid species: partially mycoheterotrophic Platanthera zijinensis and holomycoheterotrophic Platanthera guangdongensis . Comparative analysis shows that mycoheterotrophy is associated with increased substitution rates and gene loss, and the deletion of most photoreceptor genes and auxin transporter genes might be linked to the unique phenotypes of fully mycoheterotrophic orchids. Conversely, trehalase genes that catalyse the conversion of trehalose into glucose have expanded in most sequenced orchids, in line with the fact that the germination of orchid non-endosperm seeds needs carbohydrates from fungi during the protocorm stage. We further show that the mature plant of P. guangdongensis , different from photosynthetic orchids, keeps expressing trehalase genes to hijack trehalose from fungi. Therefore, we propose that mycoheterotrophy in mature orchids is a continuation of the protocorm stage by sustaining the expression of trehalase genes. Our results shed light on the molecular mechanism underlying initial, partial and full mycoheterotrophy.