Conserved and novel responses to cytokinin treatments during flower and fruit development in Brassica napus and Arabidopsis thaliana

Hormones are an important component in the regulatory networks guiding plant development. Cytokinins are involved in different physiological and developmental processes in plants. In the model plant Arabidopsis thaliana, cytokinin application during gynoecium development produces conspicuous phenotypes. On the other hand, Brassica napus, also known as canola, is a crop plant belonging to the Brassicaceae family, as A. thaliana. This makes B. napus a good candidate to study whether the cytokinin responses observed in A. thaliana are conserved in the same plant family. Here, we observed that cytokinin treatment in B. napus affects different traits of flower and fruit development. It increases ovule and seed number, affects stamen filament elongation and anther maturation, and causes a conspicuous overgrowth of tissue in petals and gynoecia. Furthermore, cytokinin recovers replum development in both wild type B. napus and in the A. thaliana rpl ntt double mutant, in which no replum is visible. These results indicate both conserved and novel responses to cytokinin in B. napus. Moreover, in this species, some cytokinin-induced phenotypes are inherited to the next, untreated generation, suggesting that cytokinins may trigger epigenetic modifications.