Researchers from the Laboratory of Organic Electronics at Linköping University who previously developed a drug delivery ion pump constructed from organic electronic components also collaborated with researchers from the Umeå Plant Science Centre to use the ion pump to control the root growth of a small flowering plant, the thale cress (Arabidopsis thaliana).
In the spring of 2015, researchers from the Laboratory of Organic Electronics at Linköping University presented a microfabricated ion pump with the ability to pump in the correct dose of a naturally occurring pain-relief agent exactly where it was needed. This was a first step towards effective treatment of such conditions as chronic pain.
In the autumn of the same year, the researchers presented results showing how they had caused roses to absorb a water-soluble conducting polymer, enabling them to create a fully operational transistor in the rose stem. The researchers said the term "flower power" suddenly took on a whole new meaning.
Assistant Professor David Poxson, Laboratory of Organic Electronics, teamed up with the group's chief chemist, Assistant Professor Roger Gabrielsson, to develop new ion pump materials capable of transporting and delivering powerful plant signalling compounds such as the hormone auxin.
Dr. Poxson then worked closely with biologists at the Umeå Plant Science Centre to investigate highly-resolved delivery of auxin to the roots of living thale cress, Arabidopsis thaliana. This plant is to plant biologists what the fruit fly Drosophila is to researchers working in animal research: a major model organism.
The result: Electronically-controlled gradients of plant hormone were taken up by the roots. Dr. Poxson and co-author Dr. Michal Karady followed the internal auxin response with the help of fluorescent reporter proteins that change their fluorescence intensity in the presence of auxin. They observed that the internal auxin response and even the roots´ growth rate could be controlled by the ion pump delivery of auxin.
Figure: Linköping University/Umeå Plant Science Centre - Ion pump in use on the root system and De novo design of an OEIP delivering IAA in vitro
Daniel Simon, Associate Professor and head of the organic bioelectronics research area in the Laboratory of Organic Electronics, Linköping University, said, "Around 10 years ago, we started considering applying our ion pump drug delivery devices to plants. It wasn't until several years later that we teamed up with Professor Markus Grebe and colleagues at the Umeå Plant Science Centre and finally discovered that the ion pump could be of great use to plant biologists."
Professor Markus Grebe at Umeå Plant Science Centre, said, "We have accomplished a ground-breaking step for plant research by our multidisciplinary effort." Markus added, "Several research groups from Umeå Plant Science Centre and Linköping University have been involved. The pump will likely allow us to locally apply not only auxin but also a variety of other hormones to plants in an electronically controlled manner. This will help us to study the impact of these hormones on plant growth and development at tissue and cellular resolution."
Daniel Simon, continued, "These new DendrolyteTM materials also paves the way for future ion pump capabilities in a variety of areas, for example delivery of larger aromatic compounds like plant hormones or even certain pharmaceuticals."
Professor Magnus Berggren, head of the Laboratory of Organic Electronics, said, "This is an important advance: we now know not only that we can use the ion pump in plants, but also that we can regulate their physiology and growth."
David J. Poxson | Michal Karady | Roger Gabrielsson | Aziz Y. Alkattan | Anna Gustavsson | Siamsa M. Doyle | Stéphanie Robert | Karin Ljung | Markus Grebe | Daniel T. Simon | Magnus Berggren,/p>
Hormones play a crucial role in the coordination of the physiological processes within and between the cells and tissues of plants. However, due to a lack of capable technologies, direct and dynamic interactions with plants’ hormone-signaling systems remains limited. Here, we demonstrate the use of an organic electronic device—the organic electronic ion pump—to deliver the plant hormone auxin to the living root tissues of Arabidopsis thaliana seedlings, inducing differential concentration gradients and modulating plant physiology. Electronically regulated transport of aromatic structures such as auxin in an organic electronic device was achieved by synthesis of a previously unidentified class of dendritic polyelectrolyte. Such bioelectronic technology opens the door for precise, electronically mediated control of a plant’s growth and development.
The organic electronic ion pump (OEIP) provides flow-free and accurate delivery of small signaling compounds at high spatiotemporal resolution. To date, the application of OEIPs has been limited to delivery of nonaromatic molecules to mammalian systems, particularly for neuroscience applications. However, many long-standing questions in plant biology remain unanswered due to a lack of technology that precisely delivers plant hormones, based on cyclic alkanes or aromatic structures, to regulate plant physiology. Here, we report the employment of OEIPs for the delivery of the plant hormone auxin to induce differential concentration gradients and modulate plant physiology. We fabricated OEIP devices based on a synthesized dendritic polyelectrolyte that enables electrophoretic transport of aromatic substances. Delivery of auxin to transgenic Arabidopsis thaliana seedlings in vivo was monitored in real time via dynamic fluorescent auxin-response reporters and induced physiological responses in roots. Our results provide a starting point for technologies enabling direct, rapid, and dynamic electronic interaction with the biochemical regulation systems of plants.