Engineering chromosome number in plants.

Genomic DNA is organized into chromosomes, and different species have different numbers of chromosomes. For example, humans have 23 pairs, whereas the model plant Arabidopsis thaliana only has 5 pairs. Chromosome number is one of the defining features of a species, yet, in most cases, it is not known why the chromosome number is what it is or what the consequences might be if the chromosome number was altered. On page 843 of this issue, Rönspies et al. (1) report directed chromosome fusion in A. thaliana. The authors used CRISPR technology to create fertile plants with a reduced, eight-chromosome karyotype. Their work dem onstrates that plant genomes are resilient to large-scale architectural changes and establishes groundwork for experimentally manipulating plant karyotypes in both basic science and applied contexts. [ABSTRACT FROM AUTHOR]