AP2 family identification in blackberry reveals the fruit ripening/color-change-related expression of RuAP2-1 and RuAP2-6 targeted by miR172

Blackberry (Rubus spp.) fruit has high nutritional value and antioxidant effects. The role of miR172 and its target gene APETALA2 (AP2) in regulating plant growth and development and secondary metabolism has been studied. However, the regulatory effects of miR172 and AP2 on blackberry fruit ripening are unclear. Here, based on the transcriptome data from blackberry fruits at different developmental stages, candidate blackberry AP2 members were identified, and their physical and chemical properties, protein structure, and phylogeny were analyzed. Digital gene expression profiles revealed that the transcripts per million of miR172 in unripe and ripe blackberry fruits were different, and the expression levels of the potential target genes AP2-1 and AP2-6 of miR172 were relatively high in unripe blackberry fruits. RT‒qPCR showed similar results. The sequencing results of the degradation group showed that miR172-z could target RuAP2-1 and miR172-y could regulate RuAP2-6. The cleavage sites were 2503 and 2329. The sequences of RuAP2-1 and RuAP2-6 were cloned, and the complementary sequence of miR172 was found. Overall, the miR172–AP2 interaction may be important in regulating the ripening process of blackberry fruit. This study provides information for future research on the posttranscriptional regulation of blackberry AP2 family members.