Fruits represent a key evolutionary innovation for seed disposal.The earliest stage of fruit development is controlled by signals generated during fertilization.Successful fertilization produces signals that promote the decision to proceed with fruit development.This earliest stage is referred to as "fruit set".Strawberry has traditionally served as a model for the study of fruit set due to its exposed seeds and ease of manipulation.Fragaria vesca is emerging as a better model than the octoploid garden strawberry due to its diploidy and a recently sequenced genome.Auxin produced from the seed was previously shown to induce receptacle fruit in strawberry,but the underlying molecular mechanisms are not known.Using nextgeneration sequencing,we profiled mRNAs and miRNAs during early stage fruit development.Analysis of auxin and GA biosynthesis genes and their tissue-specific expression revealed that the endosperm and seedcoat may play a more prominent role than the embryo in the synthesis of auxin and GA,the signals required for fruit set.This was supported by auxin measurement in dissected fruit tissues,leading to a model in which phytohormone signals produced in the endosperm and seedcoat coordinate seed,ovary wall,and receptacle fruit development.Genome-wide profiling of miRNAs in Fragaria vesca identified two new clusters of miRNAs that target 94 F-box genes.One of the miRNAs in the new cluster is 22 nt and expressed predominantly in the receptacle fruit.It triggers phasiRNA production from six FBX genes,which amplifies the silencing to additional FBX genes.Transgenic plants are being generated to test the function of these novel miRNAs during fruit development.Together,our studies are beginning to reveal the molecular underpinnings of fruit set and early stage fruit development.Our work has been supported by the US National Science Foundation grants 0923913and 1444987.