S05 - Session O4 - Flower morphology and biometrical aspects in rolB and ORF13a Kalanchoë blossfeldiana 'Molly' lines

Authors: Yan Lin, Nasim Shadmani, Nete Kodahl, Henrik Lütken, Hanne B. Hansen, Bruno Trevenzoli Favero *

Kalanchoë blossfeldiana is one of the most important potted plants in Europe and ranks second in Denmark's best-selling ornamental species. Kalanchoë has a strong market demand, and consumers have an increasing demand for novelty and high quality of Kalanchoë products. At the same time, the flower shape and morphology play a crucial role in the breeding of new varieties. Breeding new traits using natural transformation with Rhizobium rhizogenes successfully introduced compact growth in Kalanchoë by introgression of transfer-DNA fragments of the root-inducing (Ri) plasmid into plants during infection. However, the role and function of individual rol -genes from R. rhizogenes remains unclear. This work aimed at investigating the effect of individual constructs overexpressing rol Band ORF13ain K. blossfeldiana 'Molly' by assessing biometrical and morphological features. Plants transformed with rol B and ORF13a had 30% and 37% less height compared to wild type (WT), respectively, at 90 days after propagation. The rol B line plant diameter showed a reduction of 25% while ORF13a was 34% reduced in comparison to WT. Additionally, the leaf number of rol B and ORF13a was 40% less than WT. Moreover, the flower morphology of rol B and ORF13a showed markedly altered flower shapes compared to the WT. The transgenic lines exhibited lobose corollas, where the four petals were not present in a cross as normal, but instead fan-shaped. In addition, the petal edges of transgenic lines were not smooth as WT, but exhibited curly and irregular edges. Therefore, single gene transformation with rol B and ORF13a resulted in different compactness levels and flower morphological features of K. blossfeldiana 'Molly', demonstrating that unexplored ORFs present a novel feature in terms of dwarfed phenotypes.