Protecting the future of tomatoes: Why breeding resistant varieties requires rigorous hygiene

By Frank Millenaar

Nobody wants to be in contact with a virus. Ever since its outbreak in 2015, tomato growers do everything in their power to avoid Tomato Brown Rugose Fruit Virus (ToBRFV). But for my job, I need the virus! 

As a pre-breeder specializing in tomato traits, I am dedicated to creating robust, disease-resistant tomatoes, particularly against threats like ToBRFV. But you have to know your enemy. That’s why developing these urgently needed varieties requires handling ToBRFV pathogens and infected plants. In the development and selection of these robust tomatoes we need to test them for their susceptibility or resistance for ToBRFV. 

In our regular greenhouses, preventing virus infections is of utmost importance. To achieve this, we have implemented extraordinary hygiene protocols. Our daily routine is stringent – starting from changing into designated clothes and carrying out multiple hand disinfections and ensuring that no cross-contamination occurs between compartments. Every entry into a greenhouse involves wearing protective gear, which is crucial to keep the virus confined and prevent it from affecting broader crop populations. Each day concludes with meticulous decontamination procedures: all worn clothes go straight to the wash. 

We also pay attention to what we do after work, always considering the possibility that we might carry pathogens. When we go to our remote facilities, where work is being carried out with intentionally infected plants, we do it on a Friday – so two more days will pass before we enter another – virus-free – greenhouse. And a thorough shower is non-negotiable, even after wearing full protective gear.  

These measures are critical for maintaining the health of our plants. Even though they impact my personal life, I have never questioned them. After all, the rewards are high: At BASF I Nunhems, we were able to develop more than 25 ToBRFV-resistant varieties to date. Hearing about the positive impact these varieties have on growers’ productivity and crop health reaffirms the importance of our work. It's a testament to the fact that while the journey is demanding, the outcome – healthier, more resilient tomato crops and a safe livelihood for our growers – is profoundly gratifying. Every layer of protection, every regulation we adhere to, and every strict routine we follow is a step towards a more secure agricultural future. The pride I take in my work is not just in the scientific achievement but in the global contribution to food security and sustainability.