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In this report, we present the first description of nine complete genome sequences of a new strain of chayote yellow mosaic virus (ChaYMV, genus Begomovirus, family Geminiviridae), provisionally named Côte d'Ivoire (ChaYMV-CI), isolated from bitter melon (Momordica charantia) leaf samples showing yellow mosaic symptoms collected in the region of Abidjan in Côte d'Ivoire in 2013 and 2019. The nucleotide sequences of ChaYMV-CI DNA-A-like genome share the highest nucleotide sequence identities (91.8–92.5%) with those of ChaYMV isolates from Benin and Cameroon. Phylogenetic analysis confirmed the segregation of ChaYMV isolates into two distinct clades and their affiliation to Old World monopartite begomoviruses. The discovery of a new strain of ChaYMV in West Africa, at the limit of the taxonomic demarcation threshold for begomoviruses (91%), call for further investigations into the molecular diversity, geographical distribution and host range of ChaYMV in Western Africa. [ABSTRACT FROM AUTHOR]

Now that it has been realized that viruses are ubiquitous, questions have been raised on factors influencing their diversity and distribution. For phytoviruses, understanding the interplay between plant diversity and virus species richness and prevalence remains cardinal. As both the amplification and the dilution of viral species richness due to increasing host diversity have been theorized and observed, a deeper understanding of how plants and viruses interact in natural environments is needed to explore how host availability conditions viral diversity and distributions. From a unique dataset, this study explores interactions of Mastrevirus species (family Geminiviridae ) with Poales order hosts across 10 sites from three contrasting ecosystems on La Réunion. Among 273 plant pools, representing 61 Poales species, 15 Mastrevirus species were characterized from 22 hosts. The analysis revealed a strong association of mastreviruses with hosts from agroecosystems, the rare presence of viruses in coastal grasslands, and the absence of mastreviruses in subalpine areas, areas dominated by native plants. This suggests that detected mastreviruses were introduced through anthropogenic activities, emphasizing the role of humans in shaping the global pathobiome. By reconstructing the realized host-virus infection network, besides revealing a pattern of increasing viral richness with increasing host richness, we observed increasing viral niche occupancies with increasing host species richness, implying that virus realized richness at any given site is conditioned on the global capacity of the plant populations to host diverse mastreviruses. Whether this tendency is driven by synergy between viruses or by an interplay between vector population and plant richness remains to be established., Competing Interests: None declared., (© The Author(s) 2024. Published by Oxford University Press.)