Carbohydrate, as a metabolic resource for intermediary metabolism, is related to flower quality and initial ovary growth and retention [3,4,5]. Starch synthesis in rice and maize flowers is essential for mature pollen and flower retention [6,7]. In pepper flowers, defoliation and shading decreased the carbohydrate accumulation in flowers and subsequently caused flower abscission [8,9]. In addition to providing a metabolic resource, sugar acts as a signaling molecule coordinating developmental programs with available carbohydrate via the translation of nutrient status to transcriptional regulation and modulating early reproductive processes [10,11]. However, whether sugar signaling is involved in regulating flower abscission is currently unknown. Trehalose 6-phosphate synthase (TPS) genes showed a different expression pattern in abscising apple fruitlets; however, this has not yet been further investigated