The puzzle of fig mosaic: Investigating viruses, viroids, and phytoplasmas worldwide

The fig tree ( Ficus carica L.), widely cultivated in temperate regions, particularly around the Mediterranean, is an economically important fruit crop. Major fig-producing countries include Turkey, Egypt, Algeria, Morocco, and Iran. However, fig trees are susceptible to several diseases, among which fig mosaic disease (FMD) is the most prominent. First reported in California in the 1930s, FMD remains a major constraint to fig production, causing significant economic losses. Symptoms include chlorotic spots, vein thinning, leaf edge necrosis, and mosaic patterns on leaves and fruits. Although recognized for decades, the etiology of FMD has only been elucidated in recent years, revealing the association of at least 17 viruses, 4 viroids, and 2 phytoplasmas. These include highly prevalent agents such as fig mosaic virus (FMV) and fig badnavirus 1 (FBV-1), alongside other viruses of variable prevalence and uncertain pathogenic roles. Notably, this review is the first to describe the potential involvement of two phytoplasmas, ‘Candidatus Phytoplasma asteris’ and ‘Candidatus Phytoplasma solani’ , in the FMD complex. This review summarizes the current global understanding of FMD, focusing on its worldwide distribution, pathogen identification, transmission methods, genetic diversity, and sanitation strategies.