Suriyasak Chetphilin, Kawaguchi Ryosuke, Matsumoto Ryo, Sawada Yuta, Nong Hue Thi, Hamaoka Norimitsu, Ishibashi Yushi
Faculty of Agriculture, Kyushu University, Fukuoka, 819-0395, Japan.
Graduate School of Bioresource and Environmental Sciences, Kyushu University, Fukuoka, 819-0395, Japan.
Sci Rep. 2025 Apr 23;15(1):14135. doi: 10.1038/s41598-025-99146-x.
Rice grain chalkiness occurs when grains fill under heat stress, greatly reducing grain quality. But the effects of heat stress during grain filling on the subsequent development and adaptive traits remain to be elucidated. Here, we evaluated the effects of heat stress during parental grain filling on the thermotolerance of subsequent plants grown under heat stress after anthesis. Subsequent plants were grown from control (25 °C) and heat-exposed (30 °C) parental seeds under natural conditions until anthesis. Then plants were divided into three treatment groups-control [parental plants] - control [subsequent plants] (CC, 25 °C), control-heat (CH, 30 °C), and heat-heat (HH, 30 °C). Plants grown from heat-stressed seeds had thicker and shorter flag leaves, which delayed leaf senescence and improved photosynthesis under heat stress. HH plants also had significantly less chalkiness than those of CH plants. DNA methylation analysis revealed that heat stress during grain filling significantly hypomethylated promoters of starch biosynthesis genes and hypermethylated those of α-amylase genes. Consequently, HH plants had significantly higher expression of starch biosynthesis genes and suppressed expression of starch-degrading α-amylase genes than CH plants under heat stress. We propose that heat stress during grain filling induces adaptive transgenerational memory that allows subsequent plants to better cope with heat stress.
当谷粒在热胁迫下灌浆时会出现稻米垩白，这会大大降低稻米品质。但是灌浆期热胁迫对后续发育和适应性性状的影响仍有待阐明。在此，我们评估了亲本灌浆期热胁迫对花后在热胁迫下生长的后续植株耐热性的影响。后续植株由对照（25℃）和热暴露（30℃）的亲本种子在自然条件下生长至开花。然后将植株分为三个处理组——对照[亲本植株] - 对照[后续植株]（CC，25℃）、对照 - 热（CH，30℃）和热 - 热（HH，30℃）。由热胁迫种子长成的植株旗叶更厚且更短，这延迟了叶片衰老并改善了热胁迫下的光合作用。HH植株的垩白也明显少于CH植株。DNA甲基化分析表明，灌浆期热胁迫显著降低了淀粉生物合成基因启动子的甲基化水平，并增加了α -淀粉酶基因启动子的甲基化水平。因此，在热胁迫下，HH植株淀粉生物合成基因的表达显著高于CH植株，而淀粉降解α -淀粉酶基因的表达受到抑制。我们提出，灌浆期热胁迫诱导了适应性跨代记忆，使后续植株能够更好地应对热胁迫。
