The effects of different temperature and humidity conditions on the ripening and cracking of Annona atemoya fruit during storage by regulating the conversion of starch into soluble sugars

Atemoya is prone to soft ripening and cracking and has a short storage life at room temperature in summer and autumn in China. To better understand the mechanisms involved in fruit ripening and cracking, the effects of five temperature and humidity treatments (28 °C + 50%, 28 °C + 70%, 28 °C + 95%, 32 °C + 95%, 15 °C + 95%) were evaluated, and transcriptome analysis of the fruits was performed under storage conditions (stored for 0, 2, 4, and 6 days at 28 and 15 °C) in this study. The transcriptome results revealed that starch and sucrose metabolism was the most enriched KEGG pathway, including 485 DEGs. Compared with the 28 °C + 95% and 28 °C + 70% treatments, which accelerated the fruit ripening and cracking, low-temperature storage (15 °C + 95%) inhibited the expression of starch hydrolase genes such as GWD, LSF2, BAM3, BAM9, ISA3, and DPE2 , decreased the activities of BAM and DBE, increased the concentrations of sucrose and trehalose, slowed down the conversion rate of the starch to soluble sugar, decreased the RWC of the pulp, and effectively delayed ripening and cracking. These results provide a physiology and molecular foundation for explaining fruit softening and cracking and extending the shelf life of atemoya. • Low-temperature and high-humidity delay atemoya fruit ripening and cracking. • Starch and sucrose metabolism is the key pathway involved in atemoya fruit ripening. • GWD , BAM3 , ISA3 and DPE2 are the main starch degradation enzyme genes.