Flower traits change in response to infection with ‘Candidatus Phytoplasma mali’ in Nicotiana tabacum as model system

Flower traits such as flower colour, shape and volatile bouquet are shaped by a number of different factors, among them the interactions with pathogens. Infection with the ‘Candidatus Phytoplasma mali’ is associated with apple proliferation disease in Malus x domestica, a serious threat for commercial apple farming. Apple proliferation induces a range of symptoms on the leaves and a very reduced fruit size. However, the effects of this phytoplasma infection on floral traits are unknown. The phytoplasma presence was traced in different flower parts of the model system Nicotiana tabacum and changes in the floral reproductive tissue and other floral traits were explored. ‘Ca. P. mali’ was detected in floral tissues and seeds, and the floral traits changed in response to the infection. If this finding holds for M. domestica, pollinators may be able to discriminate between healthy and infected apple flowers, and their behaviour and thus pollination service may change as a consequence.