Genomic analyses of primitive, wild and cultivated citrus provide insights into asexual reproduction.

Authors: Wang, Xia and Xu, Yuantao and Zhang, Siqi and Cao, Li and Huang, Yue and Cheng, Junfeng and Wu, Guizhi and Tian, Shilin and Chen, Chunli and Liu, Yan and Yu, Huiwen and Yang, Xiaoming and Lan, Hong and Wang, Nan and Wang, Lun and Xu, Jidi and Jiang, Xiaolin and Xie, Zongzhou and Tan, Meilian and Larkin, Robert M and Chen, Ling-Ling and Ma, Bin-Guang and Ruan, Yijun and Deng, Xiuxin and Xu, Qiang

The emergence of apomixis-the transition from sexual to asexual reproduction-is a prominent feature of modern citrus. Here we de novo sequenced and comprehensively studied the genomes of four representative citrus species. Additionally, we sequenced 100 accessions of primitive, wild and cultivated citrus. Comparative population analysis suggested that genomic regions harboring energy- and reproduction-associated genes are probably under selection in cultivated citrus. We also narrowed the genetic locus responsible for citrus polyembryony, a form of apomixis, to an 80-kb region containing 11 candidate genes. One of these, CitRWP, is expressed at higher levels in ovules of polyembryonic cultivars. We found a miniature inverted-repeat transposable element insertion in the promoter region of CitRWP that cosegregated with polyembryony. This study provides new insights into citrus apomixis and constitutes a promising resource for the mining of agriculturally important genes.

Journal: Nature genetics
DOI: 10.1038/ng.3839
Year: 2017

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