The relevance of plant LTPs: from agriculture to health

Despite being considered one unique family, the lipid transfer proteins (LTPs) described in plants up to now differ greatly between each other. In fact, although they were discovered 40 years ago, the classification system that allows to study them under unified criteria was established very recently: in 2011. Nevertheless, all LTPs share a common feature that explains they are studied as a unique family: a highly conserved tridimensional structure, where the presence of a tunnel allows the transport of small molecules of lipids.

But which are these molecules? This question has been the center of a scientific debate that is still active nowadays and has been analyzed in detail in this review by compiling a great number of studies published in recent years about the topic. Zulema González, a PhD candidate from Universidad Politécnica de Madrid and lead co-author of the study, affirms that “from a structural point of view, LTPs seem to be very plastic proteins that can accommodate any lipidic chain of a small size inside them, for example a fatty acid. However, when we purify them directly from the plant and we analyze which lipid they transport, the result is always the same. This suggests that each LTP transports a specific kind of lipid, and for many of them the nature of that lipid is still unknown”.

In fact, the authors of this review remark that those differences in the lipid transported by each LTP might explain the wide variety of functions that these proteins have in the plant. For example, some LTPs make the plant resistant to the attack of microorganisms and plagues, whereas wheat plants overexpress a specific type of LTP under drought conditions, which allows them to survive during the water shortage. On the other hand, a recent research show that two LTPs are responsible to store oil inside sesame seeds, thus demonstrating the direct relationship between these proteins and the nutritional characteristics of this food. “Learning to work with LTPs, overexpressing them or silencing them at our will by using gene edition techniques, would allow us to improve our crops not only from a nutritional point of view, but also by making them more sustainable. For example, by introducing sesame's LTP in other crops we can increase the amount of beneficial fatty acids present on them, whereas by overexpressing wheat's LTP we can reduce the amount of water we need to maintain a plantation”, says Dr. Jaime Tomé, who has coordinated the review published in Plant Physiology and Biochemistry.

“Our group has always been focused, however, in studying the potentially fatal allergic reactions that these proteins induce in a great number of patients, especially from Mediterranean Europe”, comments Prof. María Garrido Arandia. This is the reason that motivates her team to develop new drugs to fight against this illness. “Right now, we are still testing our formulations in mouse models of food allergy, so we can determine if they are safe and effective before we move on to study them in clinical trials with human subjects”, says Prof. Díaz-Perlaes.

As we can see, studying LTPs is a vast and extensive field, with these proteins being both extremely beneficious and potentially harmful to human beings at the same time. “Because of that, learning to use them to our own benefit is a key objective that we must pursue in the following years”, affirms Dr. Tomé.