Format: ORAL

Abdullah El-nagish1,2, Ludwig Mann1, Seyedeh Sanam Kazemi Shahandashti3,4, Drte Harpke5, Zahra Nemati5, Maximilian W. Schmidt6, Susan Liedtke1, Frank R. Blattner5, Bjrn Usadel3,4, Tony Heitkam1,7

1 Faculty of Biology, Institute of Botany, Technische Universität Dresden, Dresden, Germany 2 Botany and Microbiology Department, Faculty of Science, Sohag University, Sohag, Egypt 3 Institute of Biological Data Science, Heinrich-Heine Universität Düsseldorf, 40225 Düsseldorf, Germany 4 IBG-4 Bioinformatics, Forschungszentrum Jülich, Wilhelm Johnen Str, 52428 Jülich, Germany 5 Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Gatersleben, Germany 6 Department of Grapevine Breeding, Hochschule of Geisenheim University 7 Institute of Biology, NAWI Graz, Karl-Franzens-Universität, 8010 Graz, Austria

Saffron crocus (Crocus sativus L.), a sterile triploid (2n = 3x = 24), is a clonally propagated crop grown for the production of saffron, the highest priced spice of the world. The evolutionary origin of the triploid C. sativus was largely unknown, but debated since the early 20th century. Recent cytogenetic and comparative next-generation sequencing approaches pointed to ancient Greece as a point of origin for saffron and concluded that C. sativus is an autotriploid species solely derived from heterogeneous diploid cytotypes of C. cartwrightianus (Schmidt et al. 2019, Nemati et al. 2019, reviewed in Kazemi-Shahandashti et al. 2022). Here, we target the processes before and after emergence of triploid saffron crocus. With this, we can look into the past, present and future of this clonal line: (1) The past: How is chromosomal variability in the progenitor C. cartwrightianus? We detected large differences in haplotype variability among chromosomes, suggesting that some C. cartwrightianus chromosomes have obtained a higher genetic diversity across the Mediterranean than others. This haplotype diversity is fixed in saffrons karyotype, a testimony to the genetic variability of C. cartwrightianus 5000 years ago. (2) The present: Are there signs of somaclonal variability in the saffron clone? By comparing triploid saffron accessions across the globe, we detect chromosomal variability in three independent instances. We conclude that several saffron lineages evolved somaclonally after emergence of triploid saffron crocus. These saffron lineages have likely spread and are retained by vegetative propagation. (3) The future: Can the global cultivation of the saffron crocus clone serve as a model for the epigenetics of adaptation? As the basis for comparative and epigenetic analyses, we are assembling reference genomes of the triploid saffron crocus and the diploid progenitor C. cartwrightianus. We show the progress of sequencing, assembly and chromosomal anchoring.