Research focus

​Plant development is in many aspects unique, and is characterized by continuous growth and flexible adjustments of the plant architecture in response to the environment. To achieve this profound adaptability, plants are able to maintain permanent stem cell populations, dedifferentiate already committed cells and, not least, to regenerate or form organs de novo. These developmental processes are governed and coordinated by signaling substances called hormones, such as auxin, abscisic acid, brassinosteroid, cytokinin, ethylene, gibberellin, and jasmonic acid. Over the past decades, physiological and genetic studies have revealed that hormone action in plants is determined by complex interactions between hormonal signaling pathways. To identify molecular components of hormonal metabolism and signaling, genetic approaches have been successfully used and have led to a basic molecular understanding of hormone action in plants. However, the molecular basis for hormonal cross-talk is still largely unknown, and its clarification represents a major challenge in the coming years for plant biology research. We use lateral root formation in Arabidopsis as a model system to study the mechanisms of hormonal interactions regulating plant organogenesis.

Lateral root organogenesis is an exceptional developmental process because it involves post-embryonic production of an entirely new organ from a small number of already differentiated cells. In addition, lateral root formation is governed by a complex network of hormonal regulations. The phytohormone auxin dominates this process. Both lateral root initiation and primordia development have been demonstrated to be governed by auxin. A crucial additional level of regulation of auxin action in lateral root organogenesis represents its intercellular distribution. In Arabidopsis, the AUX/LAX family of influx and PIN family of efflux carrier proteins mediate intercellular auxin transport and thus determine auxin distribution within plant tissues. Polar, subcellular localization of PIN proteins determine the direction of the auxin flow, and coordinated changes in PIN localization during lateral root formation play a key role in the formation of the auxin gradient and lateral root development.

Recent reports suggest that multiple signaling pathways converge in lateral root organogenesis and, in concert with spatial auxin signaling, collectively regulate this developmental process.

In our work, we use lateral root development in Arabidopsis as a system to study mechanisms of plant hormones action, the molecular basis of their interactions, and the role of these interactions in organogenesis.