Department of Pharmaceutical Biology, Julius-von-Sachs-Institute of Biosciences, University of Würzburg, Würzburg, Germany.
Center for Computational and Theoretical Biology, University of Würzburg, Würzburg, Germany.
Plant Cell Environ. 2023 Nov;46(11):3392-3404. doi: 10.1111/pce.14664. Epub 2023 Jul 10.
High-temperature stress limits plant growth and reproduction. Exposure to high temperature, however, also elicits a physiological response, which protects plants from the damage evoked by heat. This response involves a partial reconfiguration of the metabolome including the accumulation of the trisaccharide raffinose. In this study, we explored the intraspecific variation of warm temperature-induced raffinose accumulation as a metabolic marker for temperature responsiveness with the aim to identify genes that contribute to thermotolerance. By combining raffinose measurements in 250 Arabidopsis thaliana accessions following a mild heat treatment with genome-wide association studies, we identified five genomic regions that were associated with the observed trait variation. Subsequent functional analyses confirmed a causal relationship between TREHALOSE-6-PHOSPHATE SYNTHASE 1 (TPS1) and warm temperature-dependent raffinose synthesis. Moreover, complementation of the tps1-1 null mutant with functionally distinct TPS1 isoforms differentially affected carbohydrate metabolism under more severe heat stress. While higher TPS1 activity was associated with reduced endogenous sucrose levels and thermotolerance, disruption of trehalose 6-phosphate signalling resulted in higher accumulation of transitory starch and sucrose and was associated with enhanced heat resistance. Taken together, our findings suggest a role of trehalose 6-phosphate in thermotolerance, most likely through its regulatory function in carbon partitioning and sucrose homoeostasis.
高温胁迫限制了植物的生长和繁殖。然而，植物暴露在高温下也会引发一种生理反应，从而保护植物免受热损伤。这种反应涉及到代谢组的部分重新配置，包括三糖棉子糖的积累。在这项研究中，我们探索了同一种植物在温和热处理后棉子糖积累的种内变异，作为对温度响应的代谢标记，以鉴定有助于耐热性的基因。通过在 250 个拟南芥品系中进行温和热处理后的棉子糖测量，并结合全基因组关联研究，我们鉴定了与观察到的性状变异相关的五个基因组区域。随后的功能分析证实了海藻糖-6-磷酸合酶 1（TPS1）与温暖温度依赖性棉子糖合成之间的因果关系。此外，用功能不同的 TPS1 同工型对 tps1-1 缺失突变体进行互补，在更严重的热胁迫下对碳水化合物代谢有不同的影响。虽然较高的 TPS1 活性与内源蔗糖水平降低和耐热性有关，但破坏海藻糖 6-磷酸信号导致瞬态淀粉和蔗糖的积累增加，并与耐热性增强有关。总之，我们的研究结果表明，海藻糖 6-磷酸在耐热性中起作用，可能是通过其在碳分配和蔗糖稳态中的调节功能。
