A stable leaf temperature provides plants with a suitable microenvironment for photosynthesis. With global warming, extreme temperatures have become more frequent and severe; therefore, it is increasingly important to understand the fine regulation of leaf temperature under heat stress. In this study, five poplar species (Populus tomentosa, Populus simonii, Populus euphratica, Populus deltoides and Populus trichocarpa) that live in different native environments were used to analyze leaf temperature regulation. Leaf temperatures were more stable in Populus simonii and Populus euphratica (adapted to water-deficient regions) under elevated ambient temperature. Although transpiration contributes strongly to leaf cooling in poplar, the thicker epidermis and mesophyll and lower absorbance of Populus simonii and Populus euphratica leaves also help reduce leaf temperature, since their leaves absorb less radiation. Co-expression network and association analysis of a natural population of P. simonii indicated that PsiMYB60.2, PsiMYB61.2 and PsiMYB61.1 play dominant roles in coordinating leaf temperature, stomatal conductance and transpiration rate in response to heat stress. Individuals with CT-GT-GT genotypes of these three candidate genes have significantly higher water-use efficiency, and balance leaf temperature cooling with photosynthetic efficiency. Therefore, our findings have clarified the genetic basis of leaf cooling among poplar species and laid the foundation for molecular breeding of thermostable, water-conserving poplar varieties.

中文翻译：

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确定在热胁迫下降低杨树叶片温度的转录调控模块。

稳定的叶片温度为植物提供了适合光合作用的微环境。随着全球变暖，极端温度变得更加频繁和严峻。因此，了解热胁迫下叶片温度的精细调节变得越来越重要。在这项研究中，使用五种生活在不同自然环境中的杨树物种（毛白杨，小白杨，胡杨，胡杨和毛果杨）来分析叶片温度调节。西杨和胡杨的叶片温度更稳定（适用于缺水地区）在升高的环境温度下。尽管蒸腾作用大大促进了杨树叶片的降温，但更厚的表皮和叶肉以及较低的西杨和胡杨叶片的吸收也有助于降低叶片温度，因为它们的叶片吸收的辐射较少。共表达网络和的自然群体的关联性分析小叶杨表明PsiMYB60.2，PsiMYB61.2和PsiMYB61.1在协调叶片温度，气孔导度和对热胁迫的蒸腾速率中起主要作用。具有这三个候选基因的CT-GT-GT基因型的个体具有显着更高的用水效率，并且使叶片温度冷却与光合效率达到平衡。因此，我们的发现阐明了杨树种间叶片冷却的遗传基础，并为耐热，节水的杨树品种的分子育种奠定了基础。