2026-06-12 北海道大学
隣り合って生育するシロイヌナズナの個体（左：札幌市内の屋外にて佐藤安弘撮影）。五番染色体上の遺伝子座における少数派有利な選択圧（中央）と異なる対立遺伝子の混植による収量増加（右：平均±標準誤差）。右側の二つの図は論文のデータを元に平均値の変動に着目して再作図。
＜関連情報＞
- https://www.hokudai.ac.jp/news/2026/06/post-2325.html
- https://royalsocietypublishing.org/rstb/article/381/1952/20250179/482098/Negative-frequency-dependent-selection-underlies
負の頻度依存選択は隣の遺伝子型の影響を介してシロイヌナズナの収量を増加させる Negative frequency-dependent selection underlies overyielding through neighbour genotypic effects in Arabidopsis thaliana
Yasuhiro Sato
Philosophical Transactions of the Royal Society B Published:11 Jun 2026
DOI:https://doi.org/10.1098/rstb.2025.0179
Abstract
Negative frequency-dependent selection (FDS) can increase both genetic diversity and population-level mean fitness. While the dual consequence of negative FDS has been theoretically recognized, its genomic basis remains unknown. To explore a genetic link between negative FDS and overyielding, I conducted a genome-wide association study (GWAS) of neighbour genotypic effects on the growth of 98 Arabidopsis thaliana genotypes. By incorporating neighbour genotypic similarity, this GWAS analysis detected the most significant single-nucleotide polymorphism (SNP) on the fifth chromosome of A. thaliana, which was 6 kbp from a known locus responsible for indirect genetic effects. I found negative FDS on the most significant SNP, where individual plants increased their biomass in the presence of neighbours with a dissimilar allele. I also observed overyielding in which a biallelic mixture of the most significant SNP showed a 3% increase in biomass compared with monoallelic conditions. Furthermore, I focused on the genomic region near the most significant SNP and found a signature of balancing selection near a negative regulator of ethylene responses, SIRTUIN 2. The present analysis uncovered a quantitative trait locus linking balanced polymorphisms and overyielding in A. thaliana, providing a proof of principle to understand the maintenance of polymorphism and its positive impact on population productivity.
