Genome sequence and population genomics provide insights into chromosomal evolution and phytochemical innovation of Hippophae rhamnoides

第一作者：Liyang Yu

第一单位：中国林科院林业研究所

第一通讯：Jianguo Zhang

 Abstarct 

背景回顾：Plants of the Elaeagnaceae family are widely used to treat various health disorders owing to their natural phytochemicals. Seabuckthorn (Hippophae rhamnoides L.) is an economically and ecologically important species within the family with richness of biologically and pharmacologically active substances. 

胡颓子科（Elaeagnaceae）的植物因其具有天然的植物化学成分，被广泛用于各种健康问题的治疗。沙棘（Hippophae rhamnoides）是一种在经济和生态上都具有高价值的物种，含有丰富的生物活性和药理活性物质。

主要研究：Here, we present a chromosome-level genome assembly of seabuckthorn (http://hipp.shengxin.ren/), the first genome sequence of Elaeagnaceae, which has a total length of 849.04 Mb with scaffold N50 of 69.52 Mb and 30,864 annotated genes. 

本文中，作者报道了沙棘的基因组，这是胡颓子科第一个报道全基因组的物种，基因组组装大小为849.04Mb，scaffold N50长69.52Mb，共注释了30846个基因。

结果1-基因组演化：Two sequential tetraploidizations with one occurring ~36-41 million years ago (Mya) and the last ~24-27 Mya were inferred, resulting in expansion of genes related to ascorbate and aldarate metabolism, lipid biosynthesis and fatty acid elongation. Comparative genomic analysis reconstructed the evolutionary trajectories of the seabuckthorn genome with the predicted ancestral genome of 14 proto-chromosomes. 

作者鉴定到了两次连续的四倍化事件，一次发生在距今3600～4100万年间，一次发生在2400～2700万年间，导致了与抗坏血酸和aldarate代谢、脂质生物合成以及脂肪酸延伸等相关基因的扩增。比较基因组重构了沙棘基因组的演化过程，预测了其祖先的14条原型染色体。

结果2-比较转录组和代谢组：Comparative transcriptomic and metabonomic analyses identified some key genes contributing to high content of polyunsaturated fatty acids and ascorbic acid. 

比较转录组和代谢组分析鉴定到了一些作用于沙棘含高水平不饱和脂肪酸和抗坏血酸的关键基因。

结果3-群体重测序：Additionally, we generated and analyzed 55 whole-genome sequences of diverse accessions, and identified 9.80 million genetic variants in the seabuckthorn germplasms. Intriguingly, genes in selective sweep regions identified through population genomic analysis appeared to contribute to the richness of ascorbic acid (AsA) and fatty acid in seabuckthorn fruits, among which GalLDH, GMPase and ACC, TER were the potentially major-effect causative genes controlling AsA and fatty acid content of the fruit, respectively. 

另外，作者通过对55份材料的全基因组重测序分析，鉴定到了沙棘种质980万个遗传变异。有趣的是，通过群体基因组分析鉴定到的“选择清除”区域的基因似乎作用于沙棘果实中抗坏血酸和脂肪酸的富集，其中GalLDH和GMPase以及ACC和TER分别是控制沙棘果实中抗坏血酸和脂肪酸含量的主效基因。

结论：Our research offers novel insights into the molecular basis underlying phytochemical innovation of seabuckthorn, and provides valuable resources for exploring the evolution of the Elaeagnaceae family and molecular breeding.

本文的研究结果为沙棘中所含植物化学物质创新的分子基础提供了新的视野，同时为将来胡颓子科植物演化解析和分子育种提供宝贵的遗传资源。

** 张建国 **

doi: https://doi.org/10.1111/pbi.13802

Journal: Plant Biotechnology Journal

Published date: March 04, 2022