Professor Jonathan Gressel initiated his career in Plant Sciences at the Weizmann Institute of Science by studying the molecular biology of light control of flowering. Using inhibitors, he showed that mRNA was involved, but it took decades before techniques were established to allow application of his findings. Gressel switched to fungal systems, where he and colleagues described and named an important pigment, cryptochrome, which controls light effects, and is now widely known in animal as well as plant systems. He published widely about the physiology and biophysics of photomorphogenesis in Trichoderma, including papers in Science, Nature and PNAS. Later in his career, he returned to fungi, isolating potent ligninolytic fungi to upgrade the nutritional value of straw for ruminants, and later yet, as biocontrol agents against weeds.
Gressel became interested in herbicides as anti-metabolites, pioneering the development of cell-culture systems for the kinetic study of their physiology and metabolism. Decades later, these systems became the basis of robotics for screening, and for which Gressel was recognized by the Cohen Award in Plant Protection of the Agricultural Research Organization. Continuing his pioneering work with herbicides, Gressel’s group was the first to isolate an mRNA encoding a target protein for a herbicide. He became interested in the evolution of herbicide resistance and how one could delay its onset, well before it became a problem. With Lee Segel, he developed the first models on how the mode of action of a herbicide, agronomic practices, weed biology and agro-ecology interact to modulate the rate of evolution. Over the years, the extremely effective team of Gressel & Segel refined these models as new modes of resistance evolved. To this day, these models are the basis of industry recommendations to manage resistance. Gressel’s expertise in this area has been repeatedly tapped by the World Bank and several governments dealing with problems of herbicide resistance. He developed a herbicide synergist that could overcome an evolved resistance, and worked on protectants that could confer resistance to crops.
Parasitic broomrape species are major weeds attacking all the main vegetable crops in Israel. No selective chemical modes of control were available. Gressel hypothesized that transgenic crops developed abroad would allow control of the parasite while it was still underground. However, to import seed required setting up the first government committee on the cultivation of transgenic plants which Gressel helped organize. With colleagues at the Volcani Center, he then demonstrated that his concept was correct and worked. This led to a paper in Nature which caught the attention of Yussuf Wally, the Minister of Agriculture of Egypt, who requested that Gressel form a consortium for a large project to deal with this parasite. Gressel’s group genetically engineered potatoes and carrots with herbicide resistance, allowing parasite control. He extrapolated this concept to the parasitic witchweeds that are a major constraint to agriculture in Africa. He proposed using a biotech derived (non-transgenic) maize mutant, and instead of expensively spraying fields, applying the herbicide to the crop seed, a mode of application never used previously. Together with CIMMYT and Rockefeller support, the Africanized maize varieties were bred and are now commercialized in sub-Sahara Africa, with supply still not meeting demand. To further refine the technology, Gressel and colleagues developed very high capacity slow-release formulations, which are also finding uses in the developed world because they retain herbicides in the upper layer of soil, preventing run-off from entering ground water. Returning to broomrape, together with colleagues from the Volcani Center his group isolated pathogens to be used as biocontrol agents, but he quickly realized that they were not sufficiently virulent. Gressel proposed that by transgenically adding virulence genes it should be possible to enhance their effects, and published the first example where this might work in Nature Biotechnology.
There are many crops where transgenic herbicide resistance would be very useful to control weeds closely related to the crops, but gene flow from crop to weed would rapidly render such technologies useless. Jonathan Gressel devised techniques to transgenically mitigate such gene flow by tandemly attaching the gene of choice to a gene that is good or neutral for the crop but would be devastating to the weed. With students and colleagues he showed that this concept does indeed perform as expected in oilseed.
Food security and the reliance of the world population on only four crops for 80% of their calories, stimulated Gressel to write a highly acclaimed book on how under-domesticated and forgotten crops might be further domesticated into widespread cultivation by transgenically assisting them to breach the “Genetic Glass Ceiling” that holds them back.
Recently, as Emeritus Professor, Jonathan Gressel is applying his intellectual acumen and extensive laboratory and field experience to transgenically domesticate algae to cost-effectively produce oil for biofuels. His conceptual outline quickly coalesced into a high tech start-up (TransAlgae Ltd), with 20 scientists and technicians engineering marine algae with genes to enhance photosynthetic efficiency, utilization of flue gas as a carbon dioxide source, resistance to contaminants, and value of the protein residue as a aquaculture and livestock feed. Gressel envisions production of these algae in seaside desert farms, using seawater. In less than a year the company has applied for nearly 10 patents.
Jonathan Gressel is a highly recognized and decorated agricultural scientist. In Israel, he has chaired the Israel Plant Tissue Culture & Molecular Biology Association and the Israel Weed Science Society. He likewise served as president of the International Weed Science Society. Gressel was and remains actively sought after to convene meetings and symposia in Israel and abroad in his varied areas of expertise. His interest in transgenic biosafety has led to his teaching in UNIDO biosafety courses around the world. He is an editor or on the editorial board of eleven scientific journals! and is constantly invited to write critical as well as opinion reviews.