Targeted delivery in plants

Targeted Drug Delivery is an established approach in the medicinal field. It describes a process allowing selective distribution of a drug, increasing its accumulations in pre-designated organs, cells or even in specific organelles. This approach has many advantages, the main ones are reducing the required amount of a drug to achieve an effect in comparison to conventional delivery and reducing its side effects.

These advantages can be beneficial to plants as well, yet the use of this approach has never been evaluated in plant research. From the agricultural perspective, targeted herbicides, for example, can lead to reduction in amounts of herbicides needed to achieve the same effect as untargeted ones, translating into lower costs for farmers as well as reduced environmental footprints of herbicides. From the research perspective, small molecules, such as hormones or inhibitors, could be directed to specific locations, enabling to dissect their functions at a much higher resolution than available to date.

I explored the utility of triphenylphosphonium (TPP) for targeted delivery to mitochondria in plants. TPP is a known chemical moiety used prevalently to target mitochondria in many organism. However, its ability to do so in plants has not been studied before. To first establish that TPP can target mitochondria in plants, it was attached to fluorescent tags and was shown to exclusively accumulate in mitochondria in Arabidopsis thaliana cell culture and seedlings roots. To demonstrate the utility in mitochondria targeting, I synthesized TPP conjugate with the DNA gyrase inhibitor ciprofloxacin. Previous studies have shown that plant gyrase exist both in mitochondria and in the chloroplast. By using the targeting moiety, I expect to distinguish between its activities in the different organelles, providing a higher resolution for understanding of its function.