The content of soluble sugars is a vital parameter that indicates the quality of fleshy fruits such as apple ( Borkh.). Studying the patterns of accumulation of soluble sugars and regulatory mechanisms associated with fruit development is crucial for breeding improved fruit varieties. Here, we report that MdCIbHLH1, a low temperature-induced bHLH transcription factor, inhibits the accumulation of soluble sugars by regulating sugar-metabolizing enzyme activities, photosynthetic performance, and the expression of sugar-related genes in developing apple fruits. MdCIbHLH1 inhibits and expression, thus blocking the conversion of acids to sugars in apple fruits. We also discovered that MdCIbHLH1 decreases the photosynthetic rate and carbohydrate accumulation in apple leaves. Our results suggest that soluble sugar accumulation in apple fruits is influenced by multiple factors, including metabolic status, photosynthesis, and carbohydrate allocation. MdCIbHLH1 is critically involved in controlling the accumulation of soluble sugars by coordinating carbohydrate synthesis and allocation, thus influencing sugar transport and its metabolism during the development of apple fruits.

中文翻译：

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MdCIbHLH1通过协调碳水化合物的合成和分配来调节苹果果实中的糖代谢和积累

可溶性糖含量是指示苹果(Borkh.)等肉质水果品质的重要参数。研究可溶性糖的积累模式和与水果发育相关的调控机制对于培育改良水果品种至关重要。在此，我们报道MdCIbHLH1是一种低温诱导的bHLH转录因子，通过调节苹果果实发育中的糖代谢酶活性、光合性能和糖相关基因的表达来抑制可溶性糖的积累。 MdCIbHLH1 抑制 和表达，从而阻止苹果果实中酸向糖的转化。我们还发现 MdCIbHLH1 降低了苹果叶片的光合速率和碳水化合物的积累。我们的研究结果表明，苹果果实中可溶性糖的积累受到多种因素的影响，包括代谢状态、光合作用和碳水化合物分配。 MdCIbHLH1 通过协调碳水化合物的合成和分配来控制可溶性糖的积累，从而影响苹果果实发育过程中的糖转运及其代谢。