Transcriptomic and Metabolomic Analyses Provide Insights into the Formation of the Peach-like Aroma of Fragaria nilgerrensis Schlecht. Fruits

Abstract

<i>Fragaria nilgerrensis</i> Schlecht. is a wild diploid strawberry species. The intense peach-like aroma of its fruits makes <i>F. nilgerrensis</i> an excellent resource for strawberry breeding programs aimed at enhancing flavors. However, the formation of the peach-like aroma of strawberry fruits has not been comprehensively characterized. In this study, fruit metabolome and transcriptome datasets for <i>F. nilgerrensis</i> (HA; peach-like aroma) and its interspecific hybrids PA (peach-like aroma) and NA (no peach-like aroma; control) were compared. In total, 150 differentially accumulated metabolites were detected. The K-means analysis revealed that esters/lactones, including acetic acid, octyl ester, δ-octalactone, and δ-decalactone, were more abundant in HA and PA than in NA. These metabolites may be important for the formation of the peach-like aroma of <i>F. nilgerrensis</i> fruits. The significantly enriched gene ontology terms assigned to the differentially expressed genes (DEGs) were fatty acid metabolic process and fatty acid biosynthetic process. Twenty-seven DEGs were predicted to be associated with ester and lactone biosynthesis, including <i>A</i><i>AT</i>, <i>LOX</i>, <i>AOS</i>, <i>FAD</i>, <i>AIM1</i>, <i>EH</i>, <i>FAH</i>, <i>ADH</i>, and cytochrome P450 subfamily genes. Thirty-five transcription factor genes were predicted to be associated with aroma formation, including <i>bHLH</i>, <i>MYB</i>, <i>bZIP</i>, <i>NAC</i>, <i>AP2</i>, <i>GATA</i>, and <i>TCP</i><i>family members</i>. Moreover, we identified differentially expressed <i>FAD</i>, <i>AOS</i>, and cytochrome P450 family genes and <i>NAC</i>, <i>MYB</i>, and <i>AP2</i> transcription factor genes that were correlated with δ-octalactone and δ-decalactone. These findings provide key insights into the formation of the peach-like aroma of <i>F. nilgerrensis</i> fruits, with implications for the increased use of wild strawberry resources.