Chromosomal Rearrangement: From Induction by Heavy-Ion Irradiation to <i>in Vivo</i> Engineering by Genome Editing

Abstract

Chromosomal rearrangements are thought to play a role in speciation, adaptation and evolution. The effects of chromosomal rearrangements on gene expression have been reported in many species and their close relatives, and may illustrate the consequences of adaptation. To investigate the effects of chromosomal rearrangements on phenotypic changes directly, studies of experimentally induced rearrangements are required; they allow gene expression and epigenetic states to be compared between mutants and wild-types. We have developed an effective method for inducing chromosomal rearrangements with heavy-ion beam irradiation, which is a sort of ionizing radiation. Reconstruction of such rearrangements by genome editing will enable reproducible studies on the effects of chromosomal rearrangements. In the future, therefore, these techniques will usher in a new era in which researchers can create novel species with designer chromosomes.

Genomic view of heavy-ion-induced deletions associated with distribution of essential genes in Arabidopsis thaliana

“…For instance, disruption of TAGs was achieved by induction of large deletions using g-ray irradiation (Morita et al, 2007) as a forward genetic approach and Zinc Finger Nucleases as a reverse genetic approach (Qi et al, 2013). It has been also reported that C-ion or Ar-ion beam with higher LET value at 290 keV mm -1 can induce deletions ranging from several hundred bp to several Mbp, which are large enough to disrupt TAGs (Hirano et al, 2012(Hirano et al, , 2015Kazama et al, 2018;Abe et al, 2021).…”

Comprehensive effects of heavy-ion beam irradiation on sweet potato (<i>Ipomoea batatas</i> [L.] Lam.)

“…Heavy-ion beams have also been used for mutation breeding and functional studies as a powerful physical mutagen (Abe et al 2015;Hirano et al 2022;Kazama et al 2018;Tanaka et al 2010;Yamaguchi 2018). Linear energy transfer (LET; keV µm −1 ) is the amount of energy that an ionizing particle transfers to the material traversed per unit distance and is used as an index for expressing the radiation quality.…”

Effects of fertilization of male gametes with heavy-ion beam irradiation on embryo and endosperm development in <i>Cyrtanthus mackenii</i>

“…The heavy-ion beam is a type of ionizing radiation and is composed of accelerated ions heavier than helium. Thus far, mutation-inducing techniques using heavy-ion beams have been developed mainly in plants (Tanaka et al 2010;Kazama et al 2018;Abe et al 2021;Hirano et al 2022). One of the characteristics of heavy-ion beams is their high linear energy transfer (LET, keV µm 1 ), which is a unit of energy deposited per unit length along the pass of the radiation through a substance.…”