Format: ORAL

Joan Pere Pascual-Daz1,2, Neus Besol1, Ivn Prez-Lorenzo1, Sophie Maiwald3, Tony Heitkam3,4, Ronen Shtein5, Jordi Lpez-Pujol1, Neus Nualart1, Daniel Vitales1, Snia Garcia1

1 Institut Botànic de Barcelona (IBB), CSIC-CMCNB, Passeig del Migdia s/n, 08038 Barcelona, Spain. 2 Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia - Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain. 3 Faculty of Biology, Technische Universität Dresden, D-01069 Dresden, Germany. 4 Universität Graz, Institute of Biology, Holteigasse 6, AT-8010 Graz, Austria. 5 The Steinhardt Museum of Natural History, Tel Aviv University, Klausner St 12, Tel Aviv-Yafo, Israel.

Invasive alien species pose a significant threat to global biodiversity, and ornamental plant trade is one of the primary causes of introducing alien plants. One such plant is Kalanchoe houghtonii, a purpoted artificial hybrid created from the crossing between K. daigremontiana and K. tubiflora. The two parental species are native to Madagascar, but together with the hybrid have become naturalised and a threat in several regions worldwide, particularly in Mediterranean climate areas. Kalanchoe houghtonii has four morphotypes, two of which are of known synthetic origin, and the other two which may occur naturally and could be derived from spontaneous gene flow between sympatric populations of the parentals. Reproduction is primarily promoted by propagules produced by the plant. From the cytogenetic point of view, K. tubiflora is tetraploid (2n=4x=68), while K. daigremontiana is diploid (2n=2x =34). For the hybrids, there are at least two cytotypes, a triploid (2n=3x= 51) and a tetraploid (2n=4x= 68). This study aims to elucidate the interplay between invasiveness, cytotype, and genetic diversity in Kalanchoe xhoughtonii. We sampled individuals from several wild locations of the Mediterranean basin, and we complemented the sampling with herbarium and cultivar samples from different regions of the globe. We performed whole genome sequencing and analysed the plastid and nuclear genomes including the repetitive DNA content and the diversity of ribosomal DNAs to infer the genomic composition of the hybrid complex. To better understand the contribution of each parental species in the different hybrid cytotypes, we enhanced the study with fluorescent in situ hybridisation (FISH) using 18S and 5S ribosomal DNA probes. Combining genomics, molecular data, and cytogenetics, we aim to provide a holistic understanding of the evolutionary history and the invasiveness of this new and aggressive hybrid complex in the Mediterranean habitats.