Structural variation and parallel evolution of apomixis in citrus during domestication and diversification  

作　　者：Nan Wang Xietian Song Junli Ye Siqi Zhang Zhen Cao Chenqiao Zhu Jianbing Hu Yin Zhou Yue Huang Shuo Cao Zhongjie Liu Xiaomeng Wu Lijun Chai Wenwu Guo Qiang Xu Brandon S.Gaut Anna M.G.Koltunow Yongfeng Zhou Xiuxin Deng 

机构地区：[1]Key Laboratory of Horticultural Plant Biology(Ministry of Education),Huazhong Agricultural University,Wuhan 430070,China [2]Shenzhen Branch,Guangdong Laboratory of Lingnan Modern Agriculture,Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs,Agricultural Genomics Institute at Shenzhen,Chinese Academy of Agricultural Sciences,Shenzhen 518124,China [3]Department of Ecology and Evolutionary Biology,University of California Irvine,Irvine,CA 92697,USA [4]Queensland Alliance for Agriculture and Food Innovation,University of Queensland,Brisbane 4072,Australia

出　　处：《National Science Review》2022年第10期76-91,共16页国家科学评论（英文版）

基　　金：the National Key Research and Development Program of China(2018YFD1000106);the National Natural Science Foundation of China(31630065);the Modern Citrus Industry Technology System of China(CARS26);the Special Project for External Science and Technology Cooperation of Science and Technology Department of Yunnan Province(202003AD150014).

摘　　要：Apomixis,or asexual seed formation,is prevalent in Citrinae via a mechanism termed nucellar or adventitious embryony.Here,multiple embryos of a maternal genotype form directly from nucellar cells in the ovule and can outcompete the developing zygotic embryo as they utilize the sexually derived endosperm for growth.Whilst nucellar embryony enables the propagation of clonal plants of maternal genetic constitution,it is also a barrier to effective breeding through hybridization.To address the genetics and evolution of apomixis in Citrinae,a chromosome-level genome of the Hongkong kumquat(Fortunella hindsii)was assembled following a genome-wide variation map including structural variants(SVs)based on 234 Citrinae accessions.This map revealed that hybrid citrus cultivars shelter genome-wide deleterious mutations and SVs into heterozygous states free from recessive selection,which may explain the capability of nucellar embryony in most cultivars during Citrinae diversification.Analyses revealed that parallel evolution may explain the repeated origin of apomixis in different genera of Citrinae.Within Fortunella,we found that apomixis of some varieties originated via introgression.In apomictic Fortunella,the locus associated with apomixis contains the FhRWP gene,encoding an RWP-RK domain-containing protein previously shown to be required for nucellar embryogenesis in Citrus.We found the heterozygous SV in the FhRWP and CitRWP promoters from apomictic Citrus and Fortunella,due to either two or three miniature inverted transposon element(MITE)insertions.A transcription factor,FhARID,encoding an AT-rich interaction domain-containing protein binds to the MITEs in the promoter of apomictic varieties,which facilitates induction of nucellar embryogenesis.This study provides evolutionary genomic and molecular insights into apomixis in Citrinae and has potential ramifications for citrus breeding.

关 键 词：GENOMICS EVOLUTION population genetics APOMIXIS 

分 类 号：S666[农业科学—果树学]