Scientists traced roses’ thorny origins and solved a 400 million-year-old mystery

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In addition to their romantic connotations, roses are well-known for their thorns - projections on the stem that deter animals from eating the buds.

The bramble shrub, responsible for producing raspberries and blackberries, has sharp thorns, similar to certain crops like tomatoes, eggplants, barley, and rice.

in the journal Science.

These discoveries open up opportunities for scientists to develop thistle-free varieties, while also shedding new light on the evolutionary past of an incredibly diverse group of plants.

The evolution of prickles

how hair grows.

Prickles have been around for at least 400 million years - dating back to when ferns and their relatives first appeared, some of which had prickles on their stems. However, the trait has come and gone at different times in the evolution process, stated Zachary Lippman, a plant biologist and professor of genetics at Cold Spring Harbor Laboratory on Long Island, New York.

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investigator.

Quills and thorns have evolved to be a defense mechanism against herbivores - animals that eat plants - and also help with growth, competition between plants, and water retention, according to the study. Researchers had previously not known exactly how some ferns and various other unrelated plants grew the quills. The study's authors have now found that an ancient gene family known as the Lonely Guy, or LOG, has acted as a controller for the trait, turning it on and off in different species over millions of years.

Lonely Guy genes

According to Lippman, the genes control the production of a hormone called cytokinin, which plays a crucial role in a plant's fundamental cellular activities, such as cell division and growth, ultimately influencing the plant's overall development.

Lippman explained that the evolutionary history of prickles isn't one of a single ancestor gaining the trait 400 million years ago, only to lose it randomly over time. Instead, it seems that prickles can appear relatively easily in different evolutionary lineages. Now, the main question is whether the traits and the genes that create them converge by chance, or is this process more common than that?

He added, “Our study, I believe, is probably the first to truly show the strength of these tools (genetic and genome sequencing) in bridging a significant evolutionary gap to answer a fundamental question about convergent evolution in the development of organisms, whether plant or animal.”

This research provides a valuable technique for scientists to study how well thorns help plants protect themselves from herbivores. Evaluating the effectiveness of this defense system has been a problem in the past because manually removing thorns from mature plants can harm the plant and compromise its health, according to Tyler Coverdale, a professor in the University of Notre Dame's biological sciences department who wasn’t involved in this new study.

We can better understand the ecological role that physical plant defenses play by removing prickles through targeted genetic mutations," Coverdale said in an email. "Prickles are a crucial evolutionary development that enable plants to withstand herbivory, which is why many of the thorny Solanum plants are found in areas with high past diversity of large herbivores. Without this important innovation, Solanum would likely have a much more limited range and diversity.

Genetically removing prickles

Before discovering the method, growers tried to develop thornless roses by cross-breeding them with a rose variety that already didn't have prickles.

Now that the gene behind the prickles has been pinpointed, experts can remove the prickles using genome editing tools such as CRISPR, a technique researchers use to manipulate an organism's DNA. With targeted gene editing, it becomes easier to create new variations and has fewer negative effects on the plant's growth and fruit production, Coverdale said.

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Research shows that prickles form in various plant species and are also lost in those where they are absent. "There may be multiple paths, at many different levels, that result in the formation of prickles, and also where they are lost in lineages. It's possible that nature's role is simply to use past adaptations in new ways," she noted in an email.

Removing thorns could make harvesting easier and open up the possibility of getting less common fruits and veggies into stores that sell groceries.

The authors use desert raisins as an example. Desert raisins are berries that grow on prickly bushes found in Australia. If you remove the prickles, it's much easier to grow the berry, and it would be more like other common berries you find in grocery stores, such as blueberries and strawberries, as Lippman explained.

“It's really about having more knowledge and realizing how crucial mutations were in providing us with the food we eat in the amounts we do, as well as recognizing that there's more untapped potential," Lippman said. "The more we comprehend the underlying mechanisms, the better chance we'll have to fine-tune the system, or as it were, the engine, to make it perform even more efficiently.”

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