Journal Article

Genomic basis of the giga-chromosomes and giga-genome of tree peony Paeonia ostii

Jian, Jianbo, Xu, Jiabao, Xu, Chunyan, Wu, Zhangyan, Wang, Chongzhi, Jing, Yi, Zhang, Xiaoxiao, Chen, Haixin, Hu, Yonghong, Fu, Tao, Wang, Hongqi, Li, Juan, Zhang, Linjuan, Zhang, Xiao, Lin, Lihong, Huang, Liangbo, Jiang, Sanjie, Yu, Shuiyan, Chen, Xiao-Ya, Yue, Zhen, Zhang, Ying, Liu, Mingyu, Hong, Deyuan, Yuan, Junhui

2022

Overview

Tree peony ( Paeonia ostii ) is an economically important ornamental plant native to China. It is also notable for its seed oil, which is abundant in unsaturated fatty acids such as α-linolenic acid (ALA). Here, we report chromosome-level genome assembly (12.28 Gb) of P. ostii . In contrast to monocots with giant genomes, tree peony does not appear to have undergone lineage-specific whole-genome duplication. Instead, explosive LTR expansion in the intergenic regions within a short period (~ two million years) may have contributed to the formation of its giga-genome. In addition, expansion of five types of histone encoding genes may have helped maintain the giga-chromosomes. Further, we conduct genome-wide association studies (GWAS) on 448 accessions and show expansion and high expression of several genes in the key nodes of fatty acid biosynthetic pathway, including SAD , FAD2 and FAD3 , may function in high level of ALAs synthesis in tree peony seeds. Moreover, by comparing with cultivated tree peony ( P. suffruticosa ), we show that ectopic expression of class A gene AP1 and reduced expression of class C gene AG may contribute to the formation of petaloid stamens. Genomic resources reported in this study will be valuable for studying chromosome/genome evolution and tree peony breeding. Tree peony ( Paeonia ostii ) has the largest chromosome of any sequenced plants to date. Here, the authors assemble its genome and reveal the association of a list of candidate genes with fatty acid biosynthesis and the possible contribution of transposon and histone expansion to maintain the giga-chromosomes.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 38/39 / 38/43 / 38/88 / 42/35 / 45/111 / 45/15 / 45/23 / 45/90 / 45/91 / 631/208/8 / 631/449/1870 / 631/449/2653/1359 / 631/45/320 / Biosynthesis / C gene / Chromosomes / Economic importance / Ectopic expression / Fatty acids / Gene expression / Genes / Genome-wide association studies / Genome-Wide Association Study / Genomes / Genomics / Histones / Humanities and Social Sciences / Linolenic acid / multidisciplinary / Oils & fats / Ornamental plants / Paeonia / Paeonia - genetics / Plant Breeding / Science / Science (multidisciplinary) / Seeds / Stamens / Transcription factors / Trees