Developing wheat varieties with resistance to the feared leaf blotch disease may be very difficult, but recent studies carried out at Wageningen UR have brought it closer than ever. This is clear from research of the Dutch-Tunisian Sarrah Ben M’Barek-Ben Romdhane who obtained her doctorate on this subject at Wageningen University, part of Wageningen UR, on 17 October. Ben M’Barek and her colleagues mapped the complete DNA of the pathogen that causes septoria leaf blotch - the fungus Mycosphaerella graminicola. They showed that the fungus can lose entire chromosomes during sexual reproduction without any visible effect. Ben M’Barek also found that the fungus can attack wheat plants in various ways. These findings explain why it has been so difficult thus far to develop resistant wheat varieties. The new knowledge provides clues that will stimulate the development of those varieties, increasing the security and sustainability of food production. Wheat is the main food crop for regions such as North Africa and the Middle East, where it is severely threatened by the fungus Mycosphaerella graminicola, the cause of so-called septoria leaf blotch. Unfortunately, as no useable wheat varieties are resistant against the fungus, it has to be controlled with fungicide and continues to reduce food yields. This could be changed by greater insight into the genetics of the pathogen and a better understanding of the interaction between pathogen and plant.