Tushabe Donam, Altmann Franziska, Koehler Erik, Woods Sebastian, Kahl Sandra, Rosbakh Sergey
Ecology and Conservation Biology, Institute of Plant Sciences University of Regensburg Regensburg Germany.
Biodiversity Research/Systematic Botany, Institute of Biochemistry Und Biology University of Potsdam Potsdam Germany.
Ecol Evol. 2025 Mar 30;15(4):e71199. doi: 10.1002/ece3.71199. eCollection 2025 Apr.
Climate change-induced heat waves often reduce seed yields and quality via high-temperature effects in the gametophytic phase. Yet, in contrast to model and crop species, the ability of pollen and ovules to adapt or acclimate to heat stress in wild plants remains poorly understood. To address this gap, we examined the adaptation and acclimation potential of six gametophytic traits in 11 wild populations across a temperature gradient in Europe. First, we cultivated plants in a common garden to reveal differences in gametophytic traits indicative of adaptation. Next, we assessed their acclimation potential by subjecting flowering plants to two chronic heat stress (CHS) treatments: moderate (35°C/30°C) and severe (40°C/35°C) for 18 days. Also, we estimated the CHS effects on seed quantity and quality. The common garden experiment showed no intraspecific variation in gametophytic traits across the temperature gradient, suggesting these traits may not influence reproductive adaptation to local habitats. During CHS, the female gametophyte was less temperature-sensitive than the male. Moderate CHS led to larger ovaries with more large-sized ovules, while severe CHS reduced ovule numbers but increased their size. Both CHS treatments decreased pollen grain numbers, size, and anther length, with severe CHS causing greater reductions. These reductions in gametophytic traits led to lower seed yield and quality. Under both CHS treatments, acclimation potential did not vary along the temperature gradient, except for pollen size under severe CHS, which was larger in warmer climates. Our findings revealed the lack of adaptation and acclimation mechanisms in the gametophytic traits (except for pollen size) of wild populations along the temperature gradient. These findings suggest that plants may rely on alternative strategies, such as shifts in gametophyte physiology and biochemistry or flowering phenology, to respond to thermal stress associated with heat waves.
气候变化引发的热浪常常通过配子体阶段的高温效应降低种子产量和质量。然而，与模式植物和作物物种不同，野生植物中花粉和胚珠适应或适应热胁迫的能力仍知之甚少。为了填补这一空白，我们在欧洲的一个温度梯度上，研究了11个野生种群中六个配子体性状的适应和适应潜力。首先，我们在一个共同的花园中种植植物，以揭示表明适应的配子体性状差异。接下来，我们通过对开花植物进行两种慢性热胁迫（CHS）处理来评估它们的适应潜力：中度（35°C/30°C）和重度（40°C/35°C），持续18天。此外，我们估计了CHS对种子数量和质量的影响。共同花园实验表明，在温度梯度上配子体性状没有种内变异，这表明这些性状可能不会影响对当地栖息地的生殖适应。在CHS期间，雌配子体比雄配子体对温度更不敏感。中度CHS导致子房更大，有更多大尺寸的胚珠，而重度CHS减少了胚珠数量，但增加了它们的大小。两种CHS处理都减少了花粉粒数量、大小和花药长度，重度CHS导致的减少更大。这些配子体性状的减少导致种子产量和质量降低。在两种CHS处理下，适应潜力除了在重度CHS下花粉大小在温暖气候中更大外，沿温度梯度没有变化。我们的研究结果揭示了野生种群在温度梯度上配子体性状（除花粉大小外）缺乏适应和适应机制。这些发现表明，植物可能依靠其他策略，如配子体生理和生化的变化或开花物候的变化，来应对与热浪相关的热胁迫。
