S14 - Session O6 - Development and validation of qPFD® for carrot: an efficient diagnostic tool to identify and optimize the use of plant resistance inducers

Authors: Sitti Anlati Moussa, Valérie Le Clerc *, Claude Emmanuel Koutouan, Anita Suel, Marie-Noëlle Brisset, Matthieu Gaucher, Mathilde Briard

Chemical pesticides are still the primary solution to manage plant diseases offering effective protection when properly used. However, alternatives strategies are requested due to restriction of pesticide use imposed by environmental and societal concerns. It is now clearly admitted that only a combination of complementary alternatives will allow to recover the level of protection achieved with chemicals. The use of bio-plant protection products (BioPPPs) and resistant varieties are one of these alternatives among others. Today, the use of partially resistant varieties and decision support tools allow carrot growers to better rationalize the use of synthetic pesticides to deal with ALB (Alternaria leaf blight), the most damaging leaf disease in the world due to the fungus Alternaria dauci . No commercial bioPPP is currently available to fight this disease. In this context, the QuaRVeg research team (Quality and Resistance of Vegetables crops) from IRHS (Research Institute for Horticultural and Seed crops) took part in the European H2020 OPTIMA project (Optimised pest integrated management to precisely detect and control plant diseases in perennial crops and open-field vegetables) to identify bioPPPs offering efficient protection against ALB and to understand the underlying mechanisms which may be activated when some bioPPPs (among them PRIs, Plant Resistance Inducers) are sprayed on different varieties. For this purpose, the molecular diagnostic tool qPFD®, patented in 2011 on apple, was adapted to carrot. This low-density DNA chip allows screening of the PRIs products able to activate defense genes after spraying. It was used firstly to identify effective products that could be proposed to carrot producers and secondly to optimize their use with efficient varietal combination. The development of this performant diagnostic tool and its validation with two promising bioPPPs on two carrot genotypes will be presented as well as the potential applications for producers.