Holger Puchta is director of the Joseph Gottlieb Kölreuter Institute for Plant Sciences at the Karlsruhe Institute of Technology (KIT) in Germany. After his study of biochemistry at the universities of Tübingen and Munich and his PhD at the Max-Planck-Institute for Biochemistry in Munich he joined the laboratory of Barbara Hohn at the Friedrich Miescher Institute in Basel, Switzerland before he became group leader at the Leibnitz Institute for Plant Genetics in Gatersleben (IPK), Germany. In 1993 he was worldwide the first scientist to demonstrate that site-specific nucleases can be applied to induce controlled changes in plant genomes. His group also established CRISPR/Cas mediated plant chromosome engineering. Holger Puchta was awarded twice with an advanced grant of the European Research Council and most recently with the Reinhard Koselleck excellence funding of the German Research Foundation. He is elected member of the German and the European Academy of Science.

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Keynote Details

Monday 29 June

Symposium 8: Gene editing for crop improvement

Crossing borders: From CRISPR/Cas-mediated plant gene editing to chromosome number change

Breeding requires the breaking or establishing genetic linkages on the chromosome level. Before, we were not only able to demonstrate that inversions up to almost chromosome size can be achieved in by application of CRISPR/Cas, but also that meiotic recombination can be redirected this way. By inducing CRISPR/Cas-mediated breaks at subcentromeric and subtelomeric sequences, we were now also able to fuse entire chromosome arms with other chromosomes, obtaining a chromosome number reduction in the process. Thus, the diploid genome of the model plant Arabidopsis thaliana could be reduced from 10 to 8 chromosomes in two different ways. In one line, both arms of chromosome 3 were fused to chromosome 1. In another line, one arm was transferred to chromosomes 1 and the other to chromosome 5. Both chromosome number-reduced lines are fully fertile, and phenotypic as well as transcription analysis reveal no changes in comparison to wild-type plants. The progeny of crosses of the 8-chromosome lines with the wild-type genotype shows reduced fertility. Interestingly, the meiotic recombination patterns of the transferred chromosome arms drastically changed in comparison to 10-chromosome lines. Thus, the directed change of chromosome numbers in plants will enable new breeding strategies as linkage groups can be redefined and genetic barriers newly established. Moreover, our data indicate that plants are highly robust to engineered karyotype changes, proving a central mechanism of plant genome evolution.