Table_1_The Effect of Ambient Temperature on Brachypodium distachyon Development.XLSX

Due to climate change, the effect of temperature on crops has become a global concern. It has been reported that minor changes in temperature can cause large decreases in crop yield. While not a crop, the model Brachypodium distachyon can help to efficiently investigate ambient temperature responses of temperate grasses, which include wheat and barley. Here, we use different accessions to explore the effect of ambient temperature on Brachypodium phenology. We recorded leaf initiation, heading time, leaf and branch number at heading, seed set time, seed weight, seed size, seed dormancy, and seed germination at different temperatures. We found that warmer temperatures promote leaf initiation so that leaf number at heading is positively correlated to temperature. Heading time is not correlated to temperature but accessions show an optimal temperature at which heading is earliest. Cool temperatures prolong seed maturation which increases seed weight. The progeny seeds of plants grown at these cool ambient temperatures show stronger dormancy, while imbibition of seeds at low temperature improves germination. Among all developmental stages, it is the duration of seed maturation that is most sensitive to temperature. The results we found reveal that temperature responses in Brachypodium are highly conserved with temperate cereals, which makes Brachypodium a good model to explore temperature responsive pathways in temperate grasses.

受气候变化影响，温度对作物的影响已成为全球关注的热点议题。已有研究表明，微小的温度波动即可导致作物产量大幅下降。尽管二穗短柄草（Brachypodium distachyon）并非作物，但它可用于高效研究温带禾本科植物（涵盖小麦与大麦）对环境温度的响应机制。本研究利用不同种质系，探究环境温度对二穗短柄草物候期的影响。我们在不同温度梯度下记录了叶片起始进程、抽穗期、抽穗时的叶片与分枝数、结实期、种子重量、种子尺寸、种子休眠性以及种子萌发率等指标。研究发现，较高温度可加快叶片起始进程，因此抽穗期的叶片数量与温度呈正相关关系。抽穗期与温度无显著相关性，但不同种质系均存在可使抽穗最早的最适温度。低温会延长种子成熟周期，进而提升种子重量。在上述低温环境下生长的植株所结的后代种子，休眠性更强；而低温吸胀处理可提升种子的萌发率。在所有发育阶段中，种子成熟时长对温度的响应最为敏感。本研究结果表明，二穗短柄草对温度的响应机制与温带谷类作物高度保守，这使其成为研究温带禾本科植物温度响应通路的理想模式体系。