The tetraploid Camellia oleifera genome provides insights into evolution, agronomic traits, and genetic architecture of oil Camellia plants

Authors: ZHANG, XINGTAN - Chinese Academy Of Agricultural Sciences; ZHANG, LIN - Central South University Of Forestry And Technology; SHI, YAN - Guangxi University; GONG, WENFANG - Guangxi University; ZHAO, GUANG - Central South University Of Forestry And Technology; XIAO, SHIXIN - Central South University Of Forestry And Technology; LIN, HAI - Central South University Of Forestry And Technology; LI, YANMIN - Central South University Of Forestry And Technology; LIAO, ZHENYANG - Chinese Academy Of Agricultural Sciences; HU, GUANXING - Central South University Of Forestry And Technology; YE, ZIQI - Central South University Of Forestry And Technology; WANG, HAIFENG - Guangxi University; XIA, ZHIQIANG - Hainan University; Cao, Heping

Submitted to: Cell Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/8/2024
Publication Date: 11/26/2024
Citation: Zhang, X., Zhang, L., Shi, Y., Gong, W., Zhao, G., Xiao, S., Lin, H., Li, Y., Liao, Z., Hu, G., Ye, Z., Wang, H., Xia, Z., Cao, H. 2024. The tetraploid Camellia oleifera genome provides insights into evolution, agronomic traits, and genetic architecture of oil Camellia plants. Cell Reports. 43(11) Article 114902. https://doi.org/10.1016/j.celrep.2024.114902.
DOI: https://doi.org/10.1016/j.celrep.2024.114902

Interpretive Summary: Camellia oleifera is a top woody oil plants and extensively cultivated to produce high-quality edible oil. However, the complex ploidy and lack of genome information have seriously hindered molecular breeding of C. oleifera. In this paper, we report a haplotype-resolved, chromosome-level genome assembly of an tetraploid C. oleifera . We also performed comprehensive analyses of genome evolution, haplotypic variations and allelic imbalance, and origin and genetic diversity. The genome information would offer valuable resources for accelerating the genomic improvement of C. oleifera to meet the increasing global consumption of high-quality edible oil.

Technical Abstract: Camellia oleifera, an economically important woody oil plant, is widely cultivated to produce high-quality edible oil. As a polyploid species, however, complex ploidy and lack of genomic information have seriously hindered molecular breeding of C. oleifera. Here, we present an 11.43 Gb haplotype-resolved, chromosome-level genome assembly of tetraploid C. oleifera (COL-tetra) which is the first reported polyploid genome in Theaceae family. We demonstrated that COL-tetra was an autotetraploid rather than allotetraploid, and high content of transposable elements led to heavy genomic methylation and altered the methylation levels of genic regions. DNA methylation was observed to play a significant role in non-balanced expression between alleles, seed development and oil biosynthesis in COL-tetra. Phylogenetic analysis and genomic in situ hybridization analysis indicated that the COL-tetra probably originated from genome doubling of diploid C. brevistyla. In-depth analyses of genetic divergence revealed significant signals of differentiation for flowering time in C. yuhsienensis, in accordance with the florescence difference, which probably accounted for reproductive isolation between C. yuhsienensis and other oil Camellia plants. Strong introgression signals were detected between COL-tetra and C. sasanqua, and between C. vietnamensis and COLhexa. The introgressed regions harbored key genes related to oil biosynthesis, floral development and response to cold, which might have affected the development of agronomic traits and adaptability to the environment. This genome of autotetraploid C. oleifera provides important insights into evolution, agronomic traits development and genetic architecture of oil Camellia plants.