Coreless apples generated by the suppression of carpel genes and hormone-induced fruit set

Abstract

Seedless fruits have high consumer appeal and have made seeded varieties obsolete in some crops. In seedless apple varieties, core tissues which normally contain the seed can be unpalatable, reducing the seedless appeal. Apples are accessory fruit with edible flesh derived from hypanthial tissue – a floral tube fused to a compound ovary. Here we show that through suppression of <i>AGAMOUS</i>-like carpel identity genes and hormone induced fruit set, it is possible to generate coreless and therefore seedless apples. Suppression of <i>AGAMOUS</i>-like genes increased petal whorls and fully eliminated carpel development. Treatments with a combination of gibberellin, cytokinin and auxin, rather than single treatments, were required for fruit initiation in these lines. Transcriptomic analysis of <i>agamous</i> RNAi lines suggested conservation of <i>AGAMOUS</i>-dependent gene networks between apple and <i>Arabidopsis</i>. In the absence of all sexual tissues, the developing fruit continues to grow and follow a ripening process similar to that of a regular apple. The coreless phenotype offers a new concept for pipfruit consumers improving convenience and reducing food waste.