New progress on the key regulatory mechanism of sugar accumulation and ripening in rose myrtle fruits

Rhodomyrtus tomentosa (Ait.) Hasskis an emerging berry fruit crop widely distributing across tropic and subtropic regions. The fruits of R. tomentosa, which contain abundant anthocyanins and sugar,are consumed freshly or processed as beverages, jams, and jellies. Owing to the thin skins and soft flesh, the berries decay rapidly after ripening and cannot be stored well at normal temperature. Although freezing can extend their shelf life, it raises production costs and thus reduces economic returns. Therefore, improving fruit quality and prolonging the post-harvest storage life of berries are of great practical importance for the quality improvement of Rhodomyrtus tomentosa.

The SWEET (Sugars Will Eventually be Exported Transporters) family members play essential roles in sugar allocation and accumulation in plants. Based on the genome and transcriptome, researchers identified the SWEET gene family from Rhodomyrtus tomentosa and found that RtSWEET6 was a hexose transporter highly expressed during the green fruit stage. Heterologous expression of RtSWEET6 in tomato advanced flowering, slowed ripening, and enhanced the accumulation of glucose and sucrose. In R. tomentosa berries, RtSWEET6 promotes sugar accumulation and suppresses ripening by altering the expression of ripening-related genes. This study characterized SWEET transporters in R. tomentosa and demonstrated that RtSWEET6 simultaneously enhanced source-to-sink sugar allocation and delayed ripening by repressing ripening-related genes, uncovering a novel connection between carbohydrate metabolism and berry development. The dual function of RtSWEET6 also enables a precise breakthrough toward the two key objectives of R. tomentosa quality improvement—high sugar content and extended shelf life.

The research findings were recently published in the Industrial Crops and Products with a title “RtSWEET6 drives the carbohydrate source-sink allocation and prevents berry ripening in Rhodomyrtus tomentosa”. This work was supported by grants from the National Natural Science Foundation of China and the Natural Science Foundation of Guangdong Province. Article link: https://doi.org/10.1016/j.indcrop.2025.122506

Figure. RtSWEET6 mediates the sugar accumulation and fruit ripening.（Image by DENG et al.）