FACEOFF · FACEOFF: Role of intra- and inter-kingdom mixed infections as major determinants of plant virus emergence through short- and long-term modifications of seed transmission rate.

Plant pests are a main limiting factor for agricultural production, and developing effective control measures is a major requirement to meet the rising food demand of a growing human population. Among pests, viruses account for more than half of emerging plant diseases. A major contributing factor to their emergence is the great capacity of plant viruses to spread rapidly and cause devastating epidemics. Thus, current management methods focus on interfering with their horizontal transmission (HT). However, even when successful, these methods do not prevent virus epidemics as these pests have other dispersal means. The main one is vertical transmission from-parent-to-offspring via seeds (VT), which can be achieved by at least 20% of all known plant viruses. The genetic and ecological determinants of this transmission mode are largely unknown, which hampers providing efficient control measures. One such determinants is the coexistence of plant viruses with other microorganisms in mixed infections within the same plant, which is frequent in nature. Although mixed infections influence many infection traits, their role as modulators of seed transmission is unknown. To fill this gap, FACEOFF will analyze how the type of coinfecting partner (virus-virus and virus-bacteria), its transmission mode (HT or VT) and its relation with the host (beneficial or pathogenic) impact virus seed transmission. The effects of these three factors will be studied in the short- and in the long-term through experimental evolution, and their molecular basis, both in the plant and the virus, will be studied through genomics and transcriptomics. Moreover, the generated data will be integrated in an epidemiological model that integrates neural networks to study how changes in seed transmission induced by mixed infections impact virus prevalence. Thus, FACEOFF will provide an unprecedented understanding on how mixed infections determine virus epidemiology via changes in seed transmission.