The dandelion PARTHENOGENESIS gene dominantly modifies Arabidopsis fertilization and embryogenesis

Parthenogenesis, the asexual reproduction of totipotent egg cells, is a common occurrence across various species, though the mechanisms controlling it are still poorly understood. In the common dandelion, Taraxacum officinale, a gene known as PARTHENOGENESIS (ToPAR) plays a crucial role in this process. This gene produces a protein with C2H2-zinc finger and EAR domain features, which is necessary for parthenogenesis and the production of clonal seeds in apomictic dandelions.

Research has shown that introducing ToPAR into other plants can induce egg cell division and maternal haploid induction, leading to the development of a synthetic apomixis system in hybrid rice.

Up until now, however, there has not been a readily available model system to thoroughly study ToPAR's function, nor has its ability to trigger cell division in non-gametic cells been tested. A recent study has addressed this gap by demonstrating that inserting ToPAR into the egg cells of Arabidopsis thaliana using a specific promoter results in reduced seed set and induces egg cell division without fertilization.

Intriguingly, the transgene derived from ToPAR is rarely passed down through the female line, often causing irregular cell divisions.

Furthermore, when ToPAR is expressed in sexual embryos under a different promoter, it disrupts cell patterning and impairs normal morphogenesis. These findings indicate that Arabidopsis thaliana can serve as a valuable model for understanding the mode of action of ToPAR, and that the involvement of specific co-factors in gamete-triggered processes is not mandatory for its function.