Michael Todd P, Ernst Evan, Hartwick Nolan, Chu Philomena, Bryant Douglas, Gilbert Sarah, Ortleb Stefan, Baggs Erin L, Sree K Sowjanya, Appenroth Klaus J, Fuchs Joerg, Jupe Florian, Sandoval Justin P, Krasileva Ksenia V, Borisjuk Ljudmylla, Mockler Todd C, Ecker Joseph R, Martienssen Robert A, Lam Eric
Plant Molecular and Cellular Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
Genome Res. 2021 Feb;31(2):225-238. doi: 10.1101/gr.266429.120. Epub 2020 Dec 23.
Rootless plants in the genus are some of the fastest growing known plants on Earth. have a reduced body plan, primarily multiplying through a budding type of asexual reproduction. Here, we generated draft reference genomes for (Benth.) Hartog & Plas, which has the smallest genome size in the genus at 357 Mb and has a reduced set of predicted protein-coding genes at about 15,000. Comparison between multiple high-quality draft genome sequences from clones confirmed loss of several hundred genes that are highly conserved among flowering plants, including genes involved in root developmental and light signaling pathways. has also lost most of the conserved nucleotide-binding leucine-rich repeat (NLR) genes that are known to be involved in innate immunity, as well as those involved in terpene biosynthesis, while having a significant overrepresentation of genes in the sphingolipid pathways that may signify an alternative defense system. Diurnal expression analysis revealed that only 13% of genes are expressed in a time-of-day (TOD) fashion, which is less than the typical ∼40% found in several model plants under the same condition. In contrast to the model plants and rice, many of the pathways associated with multicellular and developmental processes are not under TOD control in , where genes that cycle the conditions tested predominantly have carbon processing and chloroplast-related functions. The genome and TOD expression data set thus provide insight into the interplay between a streamlined plant body plan and optimized growth.
该属的无根植物是地球上已知生长最快的一些植物。它们具有简化的身体结构，主要通过一种出芽式的无性繁殖方式进行增殖。在这里，我们为哈托格氏藓（Benth.）Hartog & Plas 生成了参考基因组草图，其基因组大小在该属中最小，为357兆碱基对，预测的蛋白质编码基因数量减少，约为15000个。对多个高质量的哈托格氏藓克隆基因组序列进行比较后发现，数百个在开花植物中高度保守的基因发生了丢失，包括参与根发育和光信号通路的基因。哈托格氏藓还丢失了大部分已知参与先天免疫以及萜类生物合成的保守核苷酸结合富含亮氨酸重复序列（NLR）基因，同时鞘脂途径中的基因显著过量表达，这可能意味着存在一种替代防御系统。昼夜表达分析表明，哈托格氏藓只有13%的基因以日节律（TOD）方式表达，这低于在相同条件下几种模式植物中典型的约40%的比例。与模式植物拟南芥和水稻不同，在哈托格氏藓中，许多与多细胞和发育过程相关的途径不受日节律控制，在测试条件下呈周期性表达的基因主要具有碳处理和叶绿体相关功能。因此，哈托格氏藓的基因组和日节律表达数据集为简化的植物体结构与优化生长之间的相互作用提供了见解。
