Gibberellic acid induced parthenocarpic ‘Honeycrisp’ apples (Malus domestica) exhibit reduced ovary width and lower acidity

Abstract

Apples: Seedless ‘Honeycrisp’ fruit develop small cores with less acidity Apple trees sprayed with a plant growth hormone called gibberellic acid develop seedless fruit that show morphological differences explained by changes in gene expression profiles. Ann Callahan from the US Department of Agriculture in Kearneysville, West Virginia, and colleagues showed that gibberellic acid induces flowers of the ‘Honeycrisp’ apple variety to develop fruit without fertilization, a process known as parthenocarpy. These fruit were seedless, with a thinner ovary at the fruit’s core and a lower acid content compared to normally pollinated controls. The researchers analyzed gene activity patterns 18 days after hormone treatment. They found differences in the expression levels of genes involved in cell division, hormone metabolism and cell wall dynamics, plus lower levels of an acidity-associated gene during early ovary development. The findings show that parthenocarpic Honeycrisp apples are possible, although they exhibit quality differences.