Musa balbisiana genome reveals subgenome evolution and functional divergence

First author: Zhuo Wang; Affiliations: Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences (中国热带农业科学院热带生物技术研究所): Haikou, China

Corresponding author: Zhiqiang Jin 

Banana cultivars (Musa ssp.) are diploid, triploid and tetraploid hybrids derived from Musa acuminata and Musa balbisiana. We presented a high-quality draft genome assembly of M. balbisiana with 430 Mb (87%) assembled into 11 chromosomes. We identified that the recent divergence of M. acuminata (A-genome) and M. balbisiana (B-genome) occurred after lineage-specific whole-genome duplication, and that the B-genome may be more sensitive to the fractionation process compared to the A-genome. Homoeologous exchanges occurred frequently between A- and B-subgenomes in allopolyploids. Genomic variation within progenitors resulted in functional divergence of subgenomes. Global homoeologue expression dominance occurred between subgenomes of the allotriploid. Gene families related to ethylene biosynthesis and starch metabolism exhibited significant expansion at the pathway level and wide homoeologue expression dominance in the B-subgenome of the allotriploid. The independent origin of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) homoeologue gene pairs and tandem duplication-driven expansion of ACO genes in the B-subgenome contributed to rapid and major ethylene production post-harvest in allotriploid banana fruits. The findings of this study provide greater context for understanding fruit biology, and aid the development of tools for breeding optimal banana cultivars.

香蕉栽培种是二倍体、三倍体和四倍体的杂交种，源自于小果野蕉和野芭蕉。本文中，作者报道了野芭蕉的高质量参考基因组，大小为430Mb，共11条染色体。作者鉴定了小果野蕉（A基因组）和野芭蕉（B基因组）之间的分化发生在谱系特异性全基因组复制事件之后，并且B基因组对于全基因组之后的缩减过程显得更加敏感。在异源多倍体中，亚基因组A和B之间经常发生同源交换。异源多倍体中，亚基因组B上的乙烯生物合成及淀粉代谢相关基因家族存在显著的扩张，并且亚组间同源基因存在表达优势。亚基因组B上1-氨基环丙烷-1-羧酸氧化酶ACO基因的独立起源以及串联重复驱动的ACO基因扩张作用于异源多倍体植株果实在采后能够快速并大量产生乙烯。本文的发现为深入理解果实生物学提供了新的知识，并且有助于香蕉遗传育种工具的开发。

通讯：金志强 (http://www.catas.cn/rczjk/contents/1850/2.html)

个人简介：1979-1983年，汉中师范学院，生物学专业学士；1990-1993年，华南热带作物学院，作物遗传育种专业硕士；1995-1998年，华南热带农业大学，作物遗传育种专业博士。

研究方向：香蕉抗病、抗逆及果实品质形成的分子机制。

doi: https://doi.org/10.1038/s41477-019-0452-6

Journal: Nature Plants

Published date: July 15, 2019