AUTHOR=Meyer Chandler M. , Goldman Irwin L. , Krysan Patrick J. 

TITLE=Chromosome-level changes and genome elimination by manipulation of CENH3 in carrot (Daucus carota)

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1294551

DOI=10.3389/fpls.2023.1294551

ISSN=1664-462X

ABSTRACT=<p>Hybrid cultivars are valuable in many crop species due to their high yield, uniformity, and other desirable traits. Doubled haploids, which have two identical sets of chromosomes, are valuable for hybrid breeding because they can be produced in one generation, in comparison to the multigenerational process typically used to produce inbred parents for hybrid production. One method to produce haploid plants is manipulation of centromeric histone H3 (<italic>CENH3</italic>). This method of producing haploids has so far been successful in <italic>Arabidopsis</italic>, maize (<italic>Zea mays</italic>), and wheat (<italic>Triticum aestivum</italic>). Here we describe modification of <italic>CENH3</italic> in carrot (<italic>Daucus carot</italic>a) to test for the ability of these modifications to induce uniparental genome elimination, which is the basis for haploid induction. Base editing was used to make <italic>cenh3</italic> mutant plants with amino acid substitutions in the region of <italic>CENH3</italic> encoding the histone fold domain. These <italic>cenh3</italic> mutant plants were then outcrossed with <italic>CENH3</italic> wild-type plants. Using PCR-based genotyping assays, we identified two candidates for genome elimination. One candidate was classified as a putative aneuploid plant in which chromosome 7 is in a single copy state. The other candidate was characterized as a putative tetraploid that was likely haploid during its genesis. Our results suggest that this putative tetraploid inherited all of its chromosomes from the <italic>CENH3</italic> wild-type parent and that the genome of the <italic>cenh3</italic> mutant plant was lost. This study provides evidence that modification of <italic>CENH3</italic> in carrot has the potential to induce genome elimination and ploidy changes in carrot.</p>