環境変動を生き抜くために種子が獲得した環境記憶を明らかに！！～ “種子の記憶”を利用した、地球環境変動下における新しい食料生産技術の構築へ～

2026-05-26 九州大学

Kyushu University農学研究院の研究グループは、イネの登熟期に受けた高温環境が「種子の記憶」としてDNAメチル化に刻まれ、次世代植物の成長や収量に影響する仕組みを明らかにした。高温条件で成熟した種子では、DNAメチル化状態が変化し、その種子から育った後代作物では多数の遺伝子発現が変動していた。後代作物は分げつ数増加、高い気孔密度、早期出穂、早朝開花などの特徴を示し、高温ストレス耐性も向上していた。さらに圃場試験では、こうした「高温登熟種子」由来のイネは収量が約10％増加した。研究では、種子形成時に生じたDNAメチル化状態が後代の器官にも維持されることを確認し、環境情報が“エピゲノム記憶”として継承されることを示した。本成果は、遺伝子組換えを用いず、種子形成期の環境制御だけで農業形質を改善できる可能性を示しており、気候変動下での安定的な食料生産技術への応用が期待される。

＜関連情報＞

イネ（ Oryza sativa L.）では、穀粒成熟温度がDNAメチル化を介して種子のエピメモリーを誘導し、その後の発育を促進する Grain-maturing temperature induces seed epi-memory via DNA methylation for subsequent development in rice (Oryza sativa L.)

Chetphilin Suriyasak,Yui Oyama,Ryusuke Kawaguchi,Ryo Matsumoto,Yuta Sawada,Wun-Jin Chen,Hue Thi Nong,Norimitsu Hamaoka,Yushi Ishibashi
Plant Physiology Published:21 April 2026
DOI:https://doi.org/10.1093/plphys/kiag219

Abstract

High temperature during grain filling diminishes the yield and quality of rice (Oryza sativa L.), but whether and how it affects development and agronomic traits in the subsequent plants remain unclear. In this study, we dissected the DNA methylome of seeds that developed under heat stress (heat-treated during development seeds, HDS) or control seeds (CS), and the transcriptomes of the plants derived from these seeds. Our methylome analysis identified 457 differentially methylated regions in HDS, mostly at the promoter regions of protein-coding genes and transposons. Transcriptome analysis detected 2,824 differentially expressed genes (DEGs) between plants grown from HDS or CS. HDS-derived subsequent plants were shorter, produced more tillers, had greater stomatal density, flowered earlier, and exhibited earlier diurnal floret opening than CS-derived plants. We linked DEGs to these phenotypic changes: OsSLB1 and OsYODA1 were downregulated, promoting abundant tillering and high stomatal density, respectively; OsHd1 and OsAOC1 were upregulated, leading to early flowering and early diurnal floret opening, respectively. In HDS, the OsSLB1 and OsYODA1 promoters were hypermethylated, but the OsHd1 and OsAOC1 promoters were hypomethylated, relative to CS. Notably, these seed methylation differences remained in their derived subsequent plants. Finally, yield was 9.5% higher for HDS-derived plants than for CS-derived plants when cultivated in the field. Our findings suggest the importance of seed epigenetic memory, mediated by DNA methylation, for the development of preferred agronomic traits.