Different genomic footprint of small insertion-deletion and structural variants determines the genetic divergence of indica and japonica rice
摘要
As the two main variety groups in improved rice, IND (indica) and JAP (temperate japonica and tropical japonica), extensive studies have utilized (single-nucleotide polymorphisms) SNPs on 233 selected improved rice cultivars to analyze the genetic basis of agronomic traits during their improvement and to compare their similarities and differences. However, the roles of other types of variations, such as insertions and deletions (INDELs) and structural variations (SVs), remain relatively underexplored.
ResultsHere, using resequencing data from 233 improved rice accessions (IND: 142, JAP: 91), we identified 811,646 INDELs and 16,231 SVs in IND, and 652,793 INDELs and 10,533 SVs in JAP. The abundance of INDELs and SVs decreased as their length increased in both variety groups. INDELs and SVs also showed an uneven distribution across the chromosomes of the two variety groups. In IND, 38.92% of INDELs and 44.1% of SVs were located within the 2 kb upstream and downstream of genes; in JAP, this proportion was 38.49% for INDELs and 43.22% for SVs. By performing genome wide association studies (GWAS) using phenotypic data of six agronomic traits (heading date, flag leaf length, flag leaf width, panicle number, plant height, and thousand grain weight) along with INDELs and SVs, we identified 3,222 significant IND-INDELs, 537 significant IND-SVs, 1,996 significant JAP-INDELs, and 286 significant JAP-SVs. Comparison of significant loci revealed that IND and JAP shared only one INDEL associated with flag leaf length and one SV associated with panicle number, suggesting distinct genetic architectures determined by INDELs and SVs for these traits in the two groups. Furthermore, haplotype analysis of candidate genes demonstrated that INDELs and SVs influence key functional genes, such as the gene TAD1 (IND-INDELs) in flag leaf length, RCN2 (IND-SVs) in heading date, PLS2 (JAP-INDELs) in plant height, and OsYLC2 (JAP-SVs) in leaf development.
ConclusionsThis study analyzed the variation patterns of INDELs and SVs during the improvement of IND and JAP varieties, and identified INDELs and SVs associated with agronomic traits. These findings will provide valuable genetic and material resources for rice breeding.