Integrated analysis of high-throughput sequencing data shows abscisic acid-responsive genes and miRNAs in strawberry receptacle fruit ripening

The perception and signal transduction of the plant hormone abscisic acid (ABA) are crucial for strawberry fruit ripening, but the underlying mechanism of how ABA regulates ripening-related genes has not been well understood. By employing high-throughput sequencing technology, we comprehensively analyzed transcriptomic and miRNA expression profiles simultaneously in ABA- and nordihydroguaiaretic acid (NDGA, an ABA biosynthesis blocker)-treated strawberry fruits with temporal resolution. The results revealed that ABA regulated many genes in different pathways, including hormone signal transduction and the biosynthesis of secondary metabolites. Transcription factor genes belonging to WRKY and heat shock factor (HSF) families might play key roles in regulating the expression of ABA inducible genes, whereas the KNOTTED1-like homeobox protein and Squamosa Promoter-Binding-like protein 18 might be responsible for ABA-downregulated genes. Additionally, 20 known and six novel differentially expressed miRNAs might be important regulators that assist ABA in regulating target genes that are involved in versatile physiological processes, such as hormone balance regulation, pigments formation and cell wall degradation. Furthermore, degradome analysis showed that one novel miRNA, Fa_novel6, could degrade its target gene HERCULES1 , which likely contributed to fruit size determination during strawberry ripening. These results expanded our understanding of how ABA drives the strawberry fruit ripening process as well as the role of miRNAs in this process. Crop genetics: pathways to ripe strawberries Researchers in China have uncovered the genetic factors through which the plant hormone ABA controls strawberry ripening. Zisheng Luo’s team at Zhejiang University used high-throughput sequencing to compare gene expression in strawberry plants after they were treated with ABA or an ABA-blocker. They discovered that ABA changes the expression of genes related to other hormones, metabolite synthesis, and breaking down cell walls. The team also checked the expression of short RNA molecules which regulate gene expression, known as microRNAs (miRNAs). They found 26 miRNAs which changed expression in response to ABA, six of which were novel, and identified 18 genes regulated by these miRNAs, including a cell wall gene which may be involved in fruit enlargement. These findings clarify the molecular mechanisms linking ABA with strawberry ripening and lay the groundwork for detailed fun