The Welwitschia genome reveals a unique biology underpinning extreme longevity in deserts

• Published in: Nature communications Vol. 12; no. 1; pp. 4247 - 15
• Main Authors: Wan, Tao, Liu, Zhiming, Leitch, Ilia J., Xin, Haiping, Maggs-Kölling, Gillian, Gong, Yanbing, Li, Zhen, Marais, Eugene, Liao, Yiying, Dai, Can, Liu, Fan, Wu, Qijia, Song, Chi, Zhou, Yadong, Huang, Weichang, Jiang, Kai, Wang, Qi, Yang, Yong, Zhong, Zhixiang, Yang, Ming, Yan, Xue, Hu, Guangwan, Hou, Chen, Su, Yingjuan, Feng, Shixiu, Yang, Ji, Yan, Jijun, Chu, Jinfang, Chen, Fan, Ran, Jinhua, Wang, Xiaoquan, Van de Peer, Yves, Leitch, Andrew R., Wang, Qingfeng
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12.07.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 38; 38/91; 45; 45/23; 631/158/857; 631/181/2474; 631/208/212/2019; 631/449/2661/2665; Africa; Assembly; Biology; Cell differentiation; Chromosomes; Copy number; Cycadopsida - genetics; Cytosine; Deamination; Desert Climate; Desert plants; Deserts; DNA Methylation - genetics; Evolution, Molecular; Gene expression; Gene families; Genome, Plant; Genomes; Geography; Humanities and Social Sciences; Leaves; Longevity; Meristem - genetics; Molecular Sequence Annotation; Morphology; multidisciplinary; Plant Leaves - genetics; Plants; Rain; Science; Science (multidisciplinary); Sequence Analysis, DNA; Species Specificity; Temperature tolerance; Transcription factors; Transcriptome - genetics; Transcriptomes; Water stress; Welwitschia; Welwitschia mirabilis; Africa
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-24528-4

The gymnosperm Welwitschia mirabilis belongs to the ancient, enigmatic gnetophyte lineage. It is a unique desert plant with extreme longevity and two ever-elongating leaves. We present a chromosome-level assembly of its genome (6.8 Gb/1 C) together with methylome and transcriptome data to explore its astonishing biology. We also present a refined, high-quality assembly of Gnetum montanum to enhance our understanding of gnetophyte genome evolution. The Welwitschia genome has been shaped by a lineage-specific ancient, whole genome duplication (~86 million years ago) and more recently (1-2 million years) by bursts of retrotransposon activity. High levels of cytosine methylation (particularly at CHH motifs) are associated with retrotransposons, whilst long-term deamination has resulted in an exceptionally GC-poor genome. Changes in copy number and/or expression of gene families and transcription factors (e.g. R2R3MYB , SAUR ) controlling cell growth, differentiation and metabolism underpin the plant’s longevity and tolerance to temperature, nutrient and water stress. Welwitschia mirabilis is a unique plant that only has two leaves, but it can survive in hostile conditions of the African desert. Here, the authors report its chromosome-level genome assembly and discuss how gene function and regulation have given rise to its unique morphology and environmental adaptions.