Comprehensive elemental analysis of fruit flesh from European pear ‘La France’ and its giant fruit bud mutant indicates specific roles for B and Ca in fruit development

• GLaF fruits are heavier than WT fruits and suffer from corky spot disorder.
• During fruit development, B, K and Na do not decrease as much as other elements.
• Young GLaF fruits have lower element concentrations compared to WT fruits.
• Element concentrations in ripe GLaF fruits recovered, except for B and Ca.
• GLaF fruits might develop local B or Ca deficiency, leading to corky spot disease.

The concentrations of macro- and microelements in fruits from European pear trees (Pyrus communis ‘La France’) were analyzed at seven developmental stages, ranging from two weeks after flowering to ripe fruits. Additionally, wild-type fruits (WT) were compared to a giant fruit bud mutant (GLaF) which sets 1.5 times bigger fruits compared to WT. With proceeding fruit development element concentrations relative to the dry biomass decreased. Differences in the rate and the degree of element concentration reduction were detected. Concentrations of B, K and Na were found to decrease at a slower rate and to a lesser degree compared to other analyzed elements. In comparison to WT fruits, most elements were detected at a lower concentration in GLaF fruits in early stage samples. During GLaF fruit development most element concentrations recovered, with the exception of B and Ca. Our results highlight common and differential element accumulation patterns in developing pear fruits. We suggest that B, K and Ca play key roles in pear fruit development and propose specific homeostasis mechanisms for these elements. Since GLaF fruits are more susceptible to corky spot disorder and B and Ca are important for the proper formation of the cell wall, we suggest that local B and/or Ca deficiency is responsible for corky spot disorder found in GLaF fruits.