For the first time ever, scientists have sequenced the genome of a resurrected plant that went extinct 2000 years ago. Last seen in biblical times, the date palm has risen indeed.
Previously, a specimen called Methuselah was grown from germinated seeds of the once extinct Judean date palm (Phoenix dactylifera L). The ancient seeds were retrieved from an archaeological site in the Levant region – eastern Mediterranean – and were radiocarbon-dated to be from the 4th century BCE to the 2nd century CE.
Key research points
- Previously extinct plant resurrected from 2000-year-old seeds
- The genome of the Judean date palm was sequenced.
- It contains genes from Crete date palms which shows Roman influence in Middle East.
Now, most excitingly, researchers from New York University sequenced the genome of some of these palms and found that they had received increasing amounts of genes from another species, Phoenix theophrasti, which is grown in Crete and southern Turkey today.
“We are fortunate that date palm seeds can live a long time – in this case, more than 2,000 years – and germinate with minimal DNA damage, in the dry environment of the region,” says Michael D. Purugganan, who led the study.
“This ‘resurrection genomics’ approach is a remarkably effective way to study the genetics and evolution of past and possibly extinct species like Judean date palms.
“By reviving biological material such as germinating ancient seeds from archaeological, paleontological sites, or historical collections, we can not only study the genomes of lost populations but also, in some instances, rediscover genes that may have gone extinct in modern varieties.”
The Levant region includes present day Jordan, Israel, Palestine, Syria, Lebanon, and large parts of Turkey. Dates were a commonly eaten and traded species that, spread more widely, would end up breeding together and sharing genes.
Genomic sequencing of ancient, cultivated plants can show human migration and trade routes because the number of unique genes can be traced from their origin. When a cultivated plant has many foreign genes, migration and mixing may have occurred, but it is often difficult to know when this happened without ancient genomes.
In this paper, published in PNAS, the team shows that the Judean date palms started to increasingly collect genes from date palms from Crete and surrounding regions between the 4th century BCE to the 2nd century CE.
The team suggests that the Judean date palms likely received the foreign genes as the Roman empire expanded down into the Middle East, bringing with them dates and seeds from the Greek isles. This may have led to hybridisation of the two species.
This kind of genomic data shows the increasing influence of the Roman empire in the Levant region, the team suggests, and that more studies on ancient or resurrected plant genomes could reveal interesting patterns of migration and cultivation in history.
Dr Deborah Devis is a science journalist at The Royal Institution of Australia.
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