Conversion between 100-million-year-old duplicated genes contributes to rice subspecies divergence [article]

Jinpeng Wang, Li Wang, Chendan Wei, Jianyu Wang, Jia Teng, Shaoqi Shen, Qimeng Xiao, Shoutong Bao, Yishan Feng, Yan Zhang, Yuxian Li, Sangrong Sun (+6 others)
2020 bioRxiv   pre-print
Extensive sequence similarity between duplicated gene pairs produced by paleo-polyploidization may result from illegitimate recombination between homologous chromosomes. The genomes of Asian cultivated rice Xian/indica (XI) and Geng/japonica (GJ) have recently been updated, providing new opportunities for investigating on-going gene conversion events. Using comparative genomics and phylogenetic analyses, we evaluated gene conversion rates between duplicated genes produced by polyploidization
more » ... polyploidization 100 million years ago (mya) in GJ and XI. At least 5.19%-5.77% of genes duplicated across three genomes were affected by whole-gene conversion after the divergence of GJ and XI at ~0.4 mya, with more (7.77%-9.53%) showing conversion of only gene portions. Independently converted duplicates surviving in genomes of different subspecies often used the same donor genes. On-going gene conversion frequency was higher near chromosome termini, with a single pair of homoeologous chromosomes 11 and 12 in each genome most affected. Notably, on-going gene conversion has maintained similarity between very ancient duplicates, provided opportunities for further gene conversion, and accelerated rice divergence. Chromosome rearrangement after polyploidization may result in gene loss, providing a basis for on-going gene conversion, and may have contributed directly to restricted recombination/conversion between homoeologous regions. Gene conversion affected biological functions associated with multiple genes, such as catalytic activity, implying opportunities for interaction among members of large gene families, such as NBS-LRR disease-resistance genes, resulting in gene conversion. Duplicated genes in rice subspecies generated by grass polyploidization ~100 mya remain affected by gene conversion at high frequency, with important implications for the divergence of rice subspecies.
doi:10.1101/2020.12.22.424042 fatcat:jfpksswe2bddngcgwq6pahzjtq