Genomic characterization of the fruity aroma gene, fafad1, reveals a gene dosage effect on y-decalactone production in strawberry (fragaria ×ananassa)

Authors: OH, YOUNGJAE - University Of Florida; BARBEY, CHRISTOPHER - University Of Florida; CHANDRA, SAKET - University Of Florida; Bai, Jinhe; FAN, ZHEN - University Of Florida; Plotto, Anne; FOLTA, KEVIN - University Of Florida; WHITAKER, VANCE - University Of Florida; LEE, SEONGHEE - University Of Florida

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2021
Publication Date: 5/4/2021
Citation: Oh, Y., Barbey, C.R., Chandra, S., Bai, J., Fan, Z., Plotto, A., Folta, K., Whitaker, V., Lee, S. 2021. Genomic characterization of the fruity aroma gene, fafad1, reveals a gene dosage effect on y-decalactone production in strawberry (fragaria ×ananassa). Frontiers in Plant Science. https://doi.org/10.3389/fpls.2021.639345.
DOI: https://doi.org/10.3389/fpls.2021.639345

Interpretive Summary: Flavor quality is strongly dependent on aroma. This study identified a genetic marker within the complex strawberry genome that regulates an important aroma component of strawberry fruit, '-decalactone. The results of this work can be used by strawberry breeders to select plants that will produce flavorful fruit at an early stage of the breeding process, thus improving breeding efficiency.

Technical Abstract: Strawberry fruit produce numerous volatile compounds that contribute to their unique flavor. Among the many volatiles, '-decalactone ('-D) has the greatest contribution to the characteristic fruity aroma in strawberry fruit. The presence or absence of '-D is controlled by a single locus, FaFAD1. However, this locus has not yet been systematically characterized in the octoploid strawberry genome. It has been also reported that the volatile content greatly varies among the strawberry varieties possessing FaFAD1, suggesting that another genetic factor could be responsible for the different levels of '-D in fruits. In this study, we explored the genomic structure of FaFAD1 and determined the genetic factor that regulates variations of '-D production in cultivated octoploid strawberry. The genome-wide association studies confirmed the major locus FaFAD1 that regulates the '-D production in cultivated strawberry. With the hybrid capture-based next generation sequencing analysis, a major presence-absence variation of FaFAD1 was discovered among '-D producers and non-producers. To explore the genomic structure of FaFAD1 in the octoploid strawberry, three bacterial artificial chromosome (BAC) libraries were developed. A deletion of 8,262 bp was consistently found in the FaFAD1 region of '-D non-producing varieties. With the newly developed InDel-based codominant marker genotyping, along with '-D metabolite profiling data, we revealed the impact of gene dosage effect for the production of '-D in the octoploid strawberry varieties. Altogether, this study provides systematic information of the prominent role of FaFAD1 presence and absence polymorphism in producing '-D, and proposes that both alleles of FaFAD1 are required to produce the highest content of fruity aroma in strawberry fruit.