Tomato (Solanum lycopersicum L.) is one of the most widely cultivated crops in the world. Tomato is a plant model and the relationship between yield and biotic/abiotic stress has attracted increasing scientific interest. Tomato cultivation under sub-optimal conditions usually negatively impacts growth and development; in particular, heat stress affects several cellular and metabolic processes, such as respiration and photosynthesis. In this work, we studied the effects of chronic heat stress on various cytological and biochemical aspects using the Micro-Tom cultivar as a model. Photosynthetic efficiency decreased during heat stress while levels of post-photosynthetic sugars (sucrose, fructose, glucose and glucose 6-phosphate) oscillated during stress. Similarly, photosynthetic pigments (lutein, chlorophyll a, chlorophyll b and β-carotene) showed an oscillating downward trend with partial recovery during the stress-free phase. The energetic capacity of leaves (e.g. ATP and ADP) was altered, as well as the reactive oxygen species (ROS) profile; the latter increased during stress. Important effects were also found on the accumulation of Rubisco isoforms, which decreased in number. Heat stress also resulted in a decreased accumulation of lipids (oleic and linoleic acid). Photosynthetically alterations were accompanied by cytological changes in leaf structure, particularly in the number of lipid bodies and starch granules. Prolonged heat stress progressively compromised the photosynthetic efficiency of tomato leaves. The present study reports multi-approach information on metabolic and photosynthetic injuries and responses of tomato plants to chronic heat stress, highlighting the plant's ability to adapt to stress.

番茄（Solanum lycopersicum L.）是世界上种植最广泛的农作物之一。番茄是一种植物模型，产量与生物/非生物胁迫之间的关系吸引了越来越多的科学兴趣。次优条件下的番茄种植通常会对生长发育产生负面影响；特别是热应激会影响多种细胞和代谢过程，例如呼吸和光合作用。在这项工作中，我们使用Micro-Tom品种作为模型研究了慢性热应激对各种细胞学和生化方面的影响。在热胁迫期间光合效率降低，而在胁迫期间光合作用后糖（蔗糖，果糖，葡萄糖和6-磷酸葡萄糖）的水平振荡。同样，光合色素（叶黄素，叶绿素a，叶绿素b和β-胡萝卜素）在无应力期呈振荡下降趋势，并部分恢复。叶子的能量容量（例如ATP和ADP）以及活性氧（ROS）谱均发生了变化；后者在压力下增加。还发现了对Rubisco同工型积累的重要影响，其数量减少了。热应激还导致脂质（油酸和亚油酸）的积累减少。光合改变伴随着叶片结构的细胞学变化，尤其是脂质体和淀粉颗粒的数量。长时间的热胁迫逐渐损害了番茄叶片的光合作用效率。本研究报告了关于代谢和光合作用损伤以及番茄植物对慢性热胁迫的反应的多种方法信息，突出了该植物适应胁迫的能力。