PhD defence: At the Core of Lettuce Growth: Investigating Mechanisms of Vegetative Internode Elongation and Bolting

PLEASE NOTE: The candidate gives a layman's talk, therefore the livestream will start fifteen minutes earlier.

When you buy lettuce at the supermarket, you may not realize how much research has gone into this crop. Lettuce, however, has significant economic value, and researchers around the world are studying ways to improve it, for example to make it more resilient to climate change.

In my PhD research, I focused on stem elongation in lettuce. Stem elongation can occur early in the plant’s development, but also later, just before flowering. In the latter case, we call it bolting. Since lettuce leaves are eaten, stem elongation is usually undesirable. Moreover, bolting often makes the leaves bitter. Several environmental factors can cause a lettuce plant to bolt, such as higher temperatures and longer day lengths.

In my research, I studied hundreds of different lettuce varieties, including iceberg lettuce, butterhead lettuce, and wild lettuce. Some types show stem elongation early, while others do so much later.

Because the full DNA of these lettuce varieties is known, it was possible to investigate which genes are associated with early or late bolting.

It turns out that a specific light receptor is present only in plants that bolt early. In addition, plant hormones were found to play an important role in stem elongation in young plants, and a different light receptor was found to be involved in stem elongation under low light conditions.

These discoveries provide new avenues for future research and could, in the long term, contribute to the development of improved lettuce varieties in the supermarket.