Comparative transcriptomic analysis of split and non-split atemoya (Annona cherimola Mill. × Annona squamosa L.) fruit to identify potential genes involved in the fruit splitting process

Atemoya (Annona cherimola Mill. × Annona squamosa L.), a popular tree with high medicinal and nutritional properties in fruit, is widely cultivated in tropical South Asia, East Asia and America. As a typical climacteric fruit, atemoya fruit has a short shelf life, and splitting frequently occurs during the postharvest period. However, little information is available on the mechanism underlying fruit splitting. To gain a comprehensive perspective on the splitting process of atemoya fruit, various cDNA libraries were prepared independently for Illumina sequencing. In total, 79,699,184 reads were assembled into 38,518 unigenes. A total of 17,860 genes, including 16,190 up- and 1670 down-regulated genes, were identified as differentially expressed genes (DEGs). A number of DEGs have been assigned to most of the key components involved in different hormonal signaling pathways, indicating that the splitting process of atemoya fruit may be controlled by an intricate hormonal signaling network. Furthermore, the expression levels of most PG-, PME-, and cellulase-encoding genes increased in the split fruits compared with the non-split fruits, which likely contributed to the reduction in skin elasticity. Identification of the DEGs related to phytohormones, and cell wall will facilitate the understanding of the regulatory mechanism underlying the fruit splitting process of atemoya.