Strawberry sweetness and consumer preference are enhanced by specific volatile compounds

Breeding crops for improved flavor is challenging due to the high cost of sensory evaluation and the difficulty of connecting sensory experience to chemical composition.The main goal of this study was to identify the chemical drivers of sweetness and consumer liking for fresh strawberries(Fragaria×ananassa).Fruit of 148 strawberry samples from cultivars and breeding selections were grown and harvested over seven years and were subjected to both sensory and chemical analyses.Each panel consisted of at least 100 consumers,resulting in more than 15,000 sensory data points per descriptor.Three sugars,two acids and 113 volatile compounds were quantified.Consumer liking was highly associated with sweetness intensity,texture liking,and flavor intensity,but not sourness intensity.Partial least square analyses revealed 20 volatile compounds that increased sweetness perception independently of sugars;18 volatiles that increased liking independently of sugars;and 15 volatile compounds that had positive effects on both.Machine learning-based predictive models including sugars,acids,and volatiles explained at least 25%more variation in sweetness and liking than models accounting for sugars and acids only.Volatile compounds such asγ-dodecalactone;5-hepten-2-one,6-methyl;and multiple medium-chain fatty acid esters may serve as targets for breeding or quality control attributes for strawberry products.A genetic association study identified two loci controlling ester production,both on linkage group 6 A.Co-segregating makers in these regions can be used for increasing multiple esters simultaneously.This study demonstrates a paradigm for improvement of fruit sweetness and flavor in which consumers drive the identification of the most important chemical targets,which in turn drives the discovery of genetic targets for marker-assisted breeding.

Evolution of the MLO gene families in octoploid strawberry(Fragaria×ananassa)and progenitor diploid species identified potential genes for strawberry powdery mildew resistance

Powdery mildew(PM)caused by Podosphaera aphanis is a major fungal disease of cultivated strawberry.Mildew Resistance Locus O(MLO)is a gene family described for having conserved seven-transmembrane domains.Induced loss-of-function in specific MLO genes can confer durable and broad resistance against PM pathogens.However,the genomic structure and potential role of MLO genes for PM resistance have not been characterized yet in the octoploid cultivated strawberry.In the present study,MLO gene families were characterized in four diploid progenitor species(Fragaria vesca,F.iinumae,F.viridis,and F.nipponica)and octoploid cultivated(Fragaria×ananassa)strawberry,and potential sources of MLO-mediated susceptibility were identified.Twenty MLO sequences were identified in F.vesca and 68 identified in F.×ananassa.Phylogenetic analysis divided diploid and octoploid strawberry MLO genes into eight different clades,in which three FveMLO(MLO10,MLO17,and MLO20)and their twelve orthologs of FaMLO were grouped together with functionally characterized MLO genes conferring PM susceptibility.Copy number variations revealed differences in MLO composition among homoeologous chromosomes,supporting the distinct origin of each subgenome during the evolution of octoploid strawberry.Dissecting genomic sequence and structural variations in candidate FaMLO genes revealed their potential role associated with genetic controls and functionality in strawberry against PM pathogen.Furthermore,the gene expression profiling and RNAi silencing of putative FaMLO genes in response to the pathogen indicate the function in PM resistance.These results are a critical first step in understanding the function of strawberry MLO genes and will facilitate further genetic studies of PM resistance in cultivated strawberry.

A roadmap for research in octoploid strawberry

The cultivated strawberry(Fragaria×ananassa)is an allo-octoploid species,originating nearly 300 years ago from wild progenitors from the Americas.Since that time the strawberry has become the most widely cultivated fruit crop in the world,universally appealing due to its sensory qualities and health benefits.The recent publication of the first highquality chromosome-scale octoploid strawberry genome(cv.Camarosa)is enabling rapid advances in genetics,stimulating scientific debate and provoking new research questions.In this forward-looking review we propose avenues of research toward new biological insights and applications to agriculture.Among these are the origins of the genome,characterization of genetic variants,and big data approaches to breeding.Key areas of research in molecular biology will include the control of flowering,fruit development,fruit quality,and plant–pathogen interactions.In order to realize this potential as a global community,investments in genome resources must be continually augmented.

Correction: Strawberry sweetness and consumer preference are enhanced by specific volatile compounds

Since the publication of this article 1,the corresponding author discovered that an additional researcher contributed data and should be included as an author.Michael L.Schwieterman(Plenty Unlimited,Inc.,South San Francisco,CA 94080,US)has been added as the fifth author.

The strawberry genome:a complicated past and promising future

Within the juicy red flesh of the commercial strawberry lies a deep history that spans at least three continents and hundreds of thousands of years.The genetic heritage of this prized dessert fruit was crafted by nature,with its modern improvement driven by the indigenous Mapuche people of South America,a seafaring a French spy,and a plant-loving teenager that gathered fruits to present to a king.The many stories that punctuate the history of the modern strawberry relate to its contemporary cultivation as well as origins that span a significant portion of the globe1,2.