**Pilar Prieto**

Plant Breeding Department, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Alameda del Obispo s/n, Apartado 4084, 14080 Córdoba, Spain; pilar.prieto@ias.csic.es; Tel.: +34-957-499-293

Received: 27 October 2020; Accepted: 29 October 2020; Published: 2 November 2020

**Abstract:** The transfer of genetic variability from related species into crops has been a main objective for decades in breeding programs. Breeders have used interspecific genetic crosses and alien introgression lines to achieve this goal, but the success is always dependent on the interspecific chromosome associations between the alien chromosomes and those from the crop during early meiosis. In this Special Issue, the strength of chromosome manipulation in a breeding framework is revealed through research and review papers that combine molecular markers, cytogenetics tools and other traditional breeding techniques. The papers and reviews included in this Special Issue "Chromosome manipulation for plant breeding purposes" describe the development and/or characterization of new plant material carrying desirable traits and the study of chromosome associations and recombination during meiosis. New tools to facilitate the transfer of desired traits from a donor species into a crop can be developed by expanding the knowledge of chromosome associations during meiosis.

**Keywords:** meiosis; chromosome engineering; chromosome pairing; non-homologous recombination; cytogenetics; alien chromosome; polyploidy; aneuploidy
