Development of gene expression system in egg cells and zygotes isolated from rice and maize

Assessing the function of genes active in zygotes and egg cells is difficult due to the inaccessibility of the target tissues.  Koiso et al. isolated rice egg cells and maize zygotes using a method similar to that for extracting leaf protoplasts.  They then optimized a PEG-Ca²⁺ transfection protocol to introduce plasmid DNA for transient expression in the isolated cells.  The transfection efficiency and transgene expression level were sufficient to assess subcellular localization of the proteins encoded on the plasmid.  In addition, some of the maize zygotes were successfully regenerated into plantlets, although none demonstrated integration of the transgene into genomic DNA. However, the authors observe that this method could be employed for transient expression of CRISPR/Cas9 genome editing system. (Summary by Mike Page) Plant Direct 10.1002/pld3.10