The genome of Magnolia hypoleuca provides a new insight into cold tolerance and the evolutionary position of magnoliids

Luojing Zhou; Feixia Hou; Li Wang; Lingyu Zhang; Yalan Wang; Yanpeng Yin; Jin Pei; Cheng Peng; Xiaobo Qin; Jihai Gao

doi:10.3389/fpls.2023.1108701

The genome of Magnolia hypoleuca provides a new insight into cold tolerance and the evolutionary position of magnoliids

Front Plant Sci. 2023 Feb 10:14:1108701. doi: 10.3389/fpls.2023.1108701. eCollection 2023.

Authors

Luojing Zhou¹, Feixia Hou¹, Li Wang², Lingyu Zhang¹, Yalan Wang¹, Yanpeng Yin¹, Jin Pei¹, Cheng Peng¹, Xiaobo Qin^{3

4}, Jihai Gao¹

Affiliations

¹ State Key Laboratory of Southwestern Chinese Medicine Resources, Chengdu University of Traditional Chinese Medicine, Chengdu, China.
² Sichuan Academy of Forestry Sciences, Chengdu, China.
³ Sichuan Provincial Academy of Natural Resource Sciences, Chengdu, China.
⁴ School of Preclinical Medicine, Chengdu University, Chengdu, China.

Abstract

Magnolia hypoleuca Sieb. & Zucc, a member of the Magnoliaceae of magnoliids, is one of the most economically valuable, phylogenetic and ornamental tree species in Eastern China. Here, the 1.64 Gb chromosome-level assembly covers 96.64% of the genome which is anchored to 19 chromosomes, with a contig N50 value of 1.71 Mb and 33,873 protein-coding genes was predicted. Phylogenetic analyses between M. hypoleuca and other 10 representative angiosperms suggested that magnoliids were placed as a sister group to the eudicots, rather than sister to monocots or both monocots and eudicots. In addition, the relative timing of the whole-genome duplication (WGD) events about 115.32 Mya for magnoliid plants. M. hypoleuca was found to have a common ancestor with M. officinalis approximately 23.4 MYA, and the climate change of OMT (Oligocene-Miocene transition) is the main reason for the divergence of M. hypoleuca and M. officinalis, which was along with the division of Japanese islands. Moreover, the TPS gene expansion observed in M. hypoleuca might contribute to the enhancement of flower fragrance. Tandem and proximal duplicates of younger age that have been preserved have experienced more rapid sequence divergence and a more clustered distribution on chromosomes contributing to fragrance accumulation, especially phenylpropanoid, monoterpenes and sesquiterpenes and cold tolerance. The stronger selective pressure drived the evolution of tandem and proximal duplicates toward plant self-defense and adaptation. The reference M. hypoleuca genome will provide insights into the evolutionary process of M. hypoleuca and the relationships between the magnoliids with monocots and eudicots, and enable us to delve into the fragrance and cold tolerance produced by M. hypoleuca and provide more robust and deep insight of how the Magnoliales evolved and diversified.

Keywords: Magnolia hypoleuca; Magnoliaceae; cold tolerance; comparative genomics; evolutionary; floral scent.

Grants and funding

This work was supported by National Interdisciplinary Innovation Team of Traditional Chinese Medicine (ZYYCXTD-D-202209), Major increase and decrease of expenditure at the central level (2060302), Talent Project in Chengdu University of TCM (QNXZ2018017, QNXZ2019001), Multi-dimensional evaluation of characteristic traditional Chinese medicine resources and product development innovation team (2022C001), and Science and Technology Planning Project of Sichuan Provincial Department of Science and Technology (22CXTD0009), Sichuan Provincial Administration of Traditional Chinese Medicine Project(2021MS236).