During the surveys of caves in the northern Judean desert in 1986-89, the Archaeology Department of the Hebrew University of Jerusalem recovered a seed of unknown identity. Scientists have germinated that seed and revived the full-grown tree. Researchers were able to perform DNA, chemical, and radiocarbon analysis to trace clues of its origin.
According to the radiocarbon analysis, the seed that grew Sheba dates to between A.D. 993 and 1202. It belongs to the Commiphora genus, which is predominantly distributed in Africa, Madagascar, and the Arabian Peninsula. This genus is considered to have economic and ethnobotanical value for its aromatic gum resins or oleoresins.
The seed was well-preserved at the Department of Archaeology of Hebrew University until Dr. Sallon took it as archaeobotanical material. The seed, 1.8 cm long and weighing 0.565 g, labeled as ‘HULMKG1’, was planted at the greenhouse facility at the Center for Sustainable Agriculture (CSA) in 2010. The seedling (dubbed “Sheba”) reportedly appeared 5 weeks after planting. 14 years later, the tree stands 3 meters tall.
Before planting, scientists utilized a few methods to sprout delicate germplasm, such as soaking the seed in water for 24 hours and using gibberellic acid, which encouraged embryonic development. Following this method, the Hormoril T8 solution was used for 6 hours to facilitate rooting. Meanwhile, KF-20 organic fertilizer was used for nutrition. Then, the ancient seed was potted in new sterile potting soil, one cm below the surface at CSA. Eight weeks after the germination, 10 ml/liter of KF-20 was added to the seedling.
Following these efforts, scientists can now finally describe the morphological features of this cryptic tree.
Sheba’s bark is pale green-brown, peeling in thin, papery layers, like peeling a sheet of paper, while the underneath bark is dark green. Leaves are alternate, imparipinnately compound with three to five leaflets. The leaves have a soft, fuzzy texture at the young stage, and they become smoother in maturity. Sheba is a deciduous tree that sheds leaves during the cooler months at a mean local temperature of 24.8 °C. A small amount of oleoresin is produced after wounding the bark. Neither oleoresin nor leaves have fragrance. As Sheba hasn’t flowered yet, scientists have no clear idea of its reproductive material.
Scientists are trying to figure out the Latin name for Sheba, but they face two significant limitations. First, the phylogenetic analysis does not sample all known Commiphora species. The genus has over 200 species spread across remote areas, and only 109 of them are densely sampled to date. Therefore, there is a possibility that the unique genetic fingerprint of “Sheba” might match with some of the un-sampled species. Secondly, Sheba has not yet produced flowers and fruit that would provide distinguishing morphological features.
Researchers are trying to figure out the reason behind Sheba remaining non-reproductive or when flowering might occur in the future. Scientists suspect that its taxon naturally reproduces at a more advanced age or is it the greenhouse environment that is not conducive to its transition from a vegetative to a reproductive state.
What forces enable trees to stand upright?
This recovery of the ancient tree provides a unique opportunity to rediscover the origins of a population that once existed in the ancient southern Levant, offering a better understanding of cultivation and commerce. Reviving historic seeds has gathered a keen interest because of its potential applications, such as bringing back lost taxa, better understanding crop domestication and evolution, and improving current crops.
Journal Reference
- Sallon, S., Solowey, E., Gostel, M. R., Egli, M., Flematti, G. R., Bohman, B., Schaeffer, P., Adam, P., & Weeks, A. (2024). Characterization and analysis of a Commiphora species germinated from an ancient seed suggests a possible connection to a species mentioned in the Bible. Communications Biology, 7(1), 1-13. DOI: 10.1038/s42003-024-06721-5
