We mourn the passing of Professor Dr. Fritz Kreuzaler, a pioneer in molecular plant science, plant synthetic biology and photosynthesis engineering. Fraunhofer IME has lost a dear friend, trusted scientific adviser and highly valued mentor. His ideas, wisdom and generosity will remain an enduring source of inspiration.

Professor Kreuzaler’s scientific contributions spanned foundational research into flavonoid biosynthesis and the characterization of chalcone synthase, the visionary concept of antibody-mediated disease resistance, and ground breaking strategies to enhance photosynthesis and crop productivity. Many of his ideas were far ahead of their time and helped pave the way for important advances in modern plant biotechnology.

For many years, Professor Kreuzaler served as a member of the Fraunhofer IME Board of Trustees. Over the past 17 years, he supported the institute as a scientific adviser, contributing his ideas, experience and sound judgement. His profound understanding of plant metabolism, exceptional scientific intuition and ability to bridge fundamental biology and applied research provided invaluable guidance for our work. He challenged us to think beyond established boundaries, encouraged us to pursue ambitious ideas and generously shared the knowledge and insight gained throughout his distinguished career.

A central focus of his work was the engineering of photosynthesis to improve crop productivity. Professor Kreuzaler helped pioneer synthetic biology in plants by redesigning photorespiration to reduce the associated losses of carbon and energy. The underlying concept was first demonstrated in the model plant Arabidopsis thaliana and subsequently developed and validated in potato, where it substantially enhanced photosynthesis, plant growth and tuber yield. He later extended this vision to the development of synthetic carbon-concentrating mechanisms aimed at creating more productive and resource-efficient crops.

These concepts emerged long before the advent of today’s computational and artificial-intelligence-assisted design tools. They reflected his exceptional command of biochemistry and his rare ability to understand plants as complex, interconnected biological systems – an approach that continues to influence and guide our research.

His scientific curiosity and dedication remained undiminished until the very end. Only one week before his passing, he was still sharing new ideas with us. This final exchange captures how we will remember him: intellectually curious, forward-looking and deeply committed both to science and to the people with whom he shared it.

Professor Kreuzaler’s legacy lives on in his scientific achievements, in the ideas he set in motion and in the many people he advised, encouraged and inspired. We will remember him as an outstanding scientist, a wise mentor and a dear friend.

Our heartfelt sympathy goes to his family, his friends and all those who were close to him. We will miss him greatly and honour his memory by carrying his scientific spirit and inspiration forward.