It’s hard to imagine plucking a rose and not having to worry about being stabbed by the spikes protruding from its stem. But that could one day be a reality, thanks to the discovery of the gene responsible for prickles in numerous plant families.
Technically, these spiky protrusions are called prickles, not thorns, which are instead found on certain shrubs and trees. In addition to roses, numerous plant species bristle with these sharp defense mechanisms, which protect the plant from animals interested in munching on tender shoots, leaves, and buds. From brambles bearing blackberries and raspberries to crops like rice, tomatoes, and eggplants, prickles are a well-known adaptation against hungry herbivores.
Interestingly, the various plants with prickles are not particularly closely related. Plant prickles have been around for over 400 million years and were first grown by early ferns. However, this trait has appeared and disappeared numerous times since then, across many different plant families. Unlike certain evolutionary traits, having prickles was not passed down to today’s spiky plants from a single common ancestor but rather evolved independently in a process known as convergent evolution (the same process through which birds and bats both evolved to have wings). According to a study published last month in the journal Science, the trait appears to have evolved independently at least 28 times over the past 400 million years.
The authors of the recent study believe that they have identified the ancient gene family responsible for prickles, known as LONELY GUY (or LOG, for short). The researchers, based at Cold Spring Harbor Laboratory in New York, focused on breeding eggplants, some with prickles and some without. By cross-breeding prickly and non-prickly varieties, they found the variant of the LOG gene that resulted in prickles. They then located the LOG gene in other plants, including rice and roses, confirming the link between the specific LOG variant and prickly plant skin.
A prickly subject:
- LOG genes are responsible for far more than just prickles. They activate the production of a key hormone called cytokinin, which plays a major role in plant growth and cell division. In plants with prickles, the original function of the gene has been co-opted to help protect the plant in environments where they are vulnerable to herbivores.
- Because plants have multiple copies of the LOG gene, it is possible to revise the plant’s genetic code without negatively impacting its development. In experiments, researchers were able to remove the copy of the prickle-producing LOG gene from tomatoes and roses with the help of the gene-editing tool CRISPR.
- This discovery has the potential to make a wide range of edible plants far more accessible for human consumption. By genetically engineering species to grow without prickles, certain crops would be far easier to harvest and more species could find their way to mainstream cultivation, like Australia’s desert raisin, a berry that naturally grows on prickly bushes.
