Sometimes life (or in this case, science) is stranger than fiction. Take, for instance, the story of the aptly named Jekyll gene. In this issue of The Plant Journal, Radchuk and colleagues describe that Jekyll, required for sexual reproduction in barley, is lineage-specific and exists in two highly divergent but functionally conserved allelic forms (Radchuk, 2019). The discovery sheds light into the process of speciation within the Triticeae tribe. Jekyll regulates seed filling in barley by promoting the nourishment of the endosperm (Radchuk et al., 2006). The gene encodes a small, toxic protein associated with programmed cell death (PCD) of the nucellar projection (NP) in the developing grain. The NP, which forms from nucellus tissue, has a tightly regulated pattern of cell division, differentiation, and disintegration to ensure nutrient supply to the growing endosperm. The release of nutrients from the NP is partially associated with PCD; in the female sporophyte, Jekyll is upregulated precisely in the nucellar cell layers that are attached to the gametophyte and programmed for autolysis. Jekyll seems to be essential for the establishment of the nucellus and NP structures in the barley developing grain and plays a crucial role in flower development and seed set. The new study, by the same group that discovered the gene, now focuses on its evolutionary history and demonstrates that Jekyll is lineage-specific. The lead author, Volodymyr Radchuk, is a scientist in the Assimilate Allocation and NMR group at the Institute of Plant Genetics and Crop Plant Research (IPK) in Gatersleben, Germany. The group's leader, Ljudmilla Borisjuk, is the senior author in the study. Inspired by the contrasting nature of the gene's function (required for plant fertility, but shifts cell fate to death), Borisjuk named the gene Jekyll, in reference to the famous gothic novella “The Strange Case of Dr. Jekyll and Mr. Hyde, “in which the character Dr. Jekyll suffers from dual personality; one good, the other evil. When the authors named the Jekyll gene back in 2006, little did they know that the gene itself also has, so to speak, an interesting case of ‘dual personality’. To be precise, dual allelic state. As it often happens in science, serendipity was the route to discovery. According to Radchuk, one day he needed to amplify a Jekyll fragment and took DNA from cultivar Morex, instead of Barke as usual. Strangely, his PCR failed over and over, but when he went back to Barke DNA, it worked again. Intrigued, Radchuk tried more accessions and found others that also did not seem to contain a Jekyll sequence similar to Barke. When he expanded the search to a barley EST collection (Zhang et al., 2004), he realized that the presence of one sequence excluded the other and vice-versa, which led him to the hypothesis of allelic variation. To prove the hypothesis, the group recruited the help of colleagues with expertise in cytology, genetics, genomics, and magnetic resonance imaging (MRI). Using in situ hybridization and genetic mapping, they demonstrate that the alleles, named Jek1 and Jek3, are located on the same chromosomal locus and are inherited in a monogenic Mendelian fashion. Jek3, which encodes a protein with 51% identity to the one encoded by Jek1, can complement Jek1-deficient plants. The two allelic variants are almost equally distributed in a collection of 485 wild and domesticated barley accessions, and there is no indication that one or the other is under selection. For now, the biological implications of the high level of divergence between Jek1 and Jek3 remain unknown. The study also investigated the evolution of Jekyll genes in other species within the grass family Poaceae and demonstrated that Jekyll is found only in genomes of the closely related Triticeae and Bromeae tribes. Jekyll likely emerged de novo in the progenitor of these tribes and may have been a driver for the separation of these lineages from Brachypodieae. Genes that mediate sexual reproduction are often rapidly evolving and lineage-specific. These genes facilitate reproductive isolation, which is essential for speciation and the formation of new evolutionary lineages (Swanson and Vacquier, 2002). The role of Jekyll on the structural and functional arrangement of the grain provides a clue as to how this differentiation may have occurred: using MRI, the authors previously identified the NP as the main route for sucrose allocation to the endosperm (Melkus et al., 2011). In this study, they expand the MRI analysis to the mature seeds of many different species (see Figure) and demonstrate that the structure of the NP region differs in Triticeae and Bromeae species from the other grasses. They have uncovered the interesting phenomenon of allelic diversity, but Radchuk and his colleagues say that many questions are still waiting to be answered. For example, how did this allelic diversity arise, and why has it been preserved during evolution? Perhaps Jek1 and Jek3 are at least in part functionally distinct (e.g., operate under different environments or stress conditions)? Will one of the alleles turn out to be more like Jekyll and the other, more like Hyde?