Author:
Lou Heqiang,Song Lili,Li Xiaolong,Chen Weijie,Gao Yadi,Zheng Shan,Fei Zhangjun,Sun Xuepeng,Wu Jiasheng
Abstract
AbstractSpecies in genusTorreyaare nut trees that produce dry fruits with a wide assortment of functions. Here, we report the 19-Gb chromosome-level genome assembly ofT. grandis.The genome is shaped by an ancient whole genome duplication and recurrent LTR retrotransposon bursts. Comparative genomic analyses reveal key genes involved in reproductive organ development, cell wall biosynthesis and seed storage. Two genes encoding a C18Δ9-elongase and a C20Δ5-desaturase are identified inT. grandisto be responsible for sciadonic acid biosynthesis and both are present in diverse plant lineages except angiosperms. We demonstrate that the histidine-rich boxes of the Δ5-desaturase are crucial for its catalytic activity. Methylome analysis reveals that methylation valleys of theT. grandisseed genome harbor genes associated with important seed activities, including cell wall and lipid biosynthesis. Moreover, seed development is accompanied by DNA methylation changes that possibly fuel energy production. This study provides important genomic resource for gymnosperms and unravels key enzymes for biosynthesis of sciadonic acid as a hallmark metabolite of gymnosperms.
Publisher
Cold Spring Harbor Laboratory