How the primrose flowers in such unique formations

For over 150 years, scientists have been working to solve the mystery of the primrose plant and its two unique flowering forms. Famed naturalist Charles Darwin was drawn to the primrose and the inner workings of the plant’s reproduction.

Now in a new study published in the journal Scientific Reports, researchers from the University of East Anglia have successfully sequenced the complete genome of the primrose.

The results help shed some light on the puzzling biology of the plant.

“We started many years ago with a packet of seeds and a vision to understand the molecular genetics and developmental biology of the reproductive system Darwin described in 1862,” said Philip Gilmartin, a member of the research team.

Primula vulgaris flower with a long style and low anthers or short style and long anthers. The style of a plant is one of the main parts of the reproductive organs and allows pollen to reach the ovary via a tube. Anthers produce pollen in the plant.

Researchers have wondered why plants like the primrose flower these two ways, but after sequencing the primrose genome, it was discovered that the answer lies in the in a cluster of genes known as the S (style length) locus.

In the new study, the researchers found that the S-locus controls many genes responsible for development but is absent from half of the plants in the primrose species.

The different patterns of gene expression and activated genes depends on the S-locus which is why there are two different flowering forms.

“Completion of the genome sequence paves the way to identify the genes that are regulated by the S locus, and adds more pieces to the puzzle,” said Gilmartin. “A long line of scientists, from Darwin in the 1860s through Bateson in the early 1900s, to Haldane and Fisher in the mid 1900’s have been gripped and we continue to unravel the mystery piece by piece.”

The researchers plan to continue their investigations and see if there are similar underlying mechanisms at work in buckwheat plants, which also have two distinct flowering forms.

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By Kay Vandette, Earth.com Staff Writer