First report of <i>Pepo aphid‐borne yellows virus</i> infecting watermelon ( <i>Citrullus lanatus</i> ) in Uganda

Watermelon (Citrullus lanatus), a cucurbit of global importance, is potential cash crop in Uganda (Masika et al., 2022). In December 2021, watermelon plants with extensive yellowing mature leaves were observed field central Uganda. Although farmers associated symptoms nutritional deficiencies and moisture stress, biotic constraints like viruses can also induce such symptoms. For example, poleroviruses are reduction yield. Pepo aphid-borne yellows virus (PABYV) polerovirus that has been reported Côte d'Ivoire (Kone 2015), South Africa (Ibaba 2017), Tanzania (Desbiez 2016) Kenya (Kidanemariam 2019). The virus, mainly transmitted by aphids, was first Mali infecting summer squash (Cucurbita pepo) 2008 (Knierim 2014). Three showing (Figure 1) collected from Mukono District Samples transported on ice to the National Crops Resources Research Institute, Namulonge, for total RNA extraction RT-PCR amplification done using primers designed targeting coat protein region PABYV genome (forward 5'-GAATACGGTCGCGGTTAGATCTAGC-3', reverse 5'-GTTCTGGACCTGGCACTGGATGG-3'). Fragments expected size (588 bp) produced sent Macrogen Europe B.V (Amsterdam, Netherlands) direct sequencing. Sequence analyses showed isolates this study (GenBank Accession Nos. ON650024-ON650026) shared between 95 99% identity themselves. A BLASTn search revealed these closely related GenBank sharing 98.3-98.7% identities accessions KU315177, KJ789911, KJ789904, KU315178. This report did not show any recombination as determined RDP, GENECONV, Chimaera, MaxChi, BootScan, SiScan, 3Seq LARD programmes implemented detection programme 4 (RDP4) software. Phylogenetic clustering close relationship our those other East African countries (Kenya Tanzania) Africa. Sequences d'Ivoire, Mali, Greece formed another clade, suggesting north/west versus south/east division genetic diversity Mayotte, Indian Ocean, more basal 2). identification multiple suggests it might be widespread well-established throughout continent. Poleroviruses aphid vectors which multiply rapidly colonise new areas. addition, infected may have ignored or misdiagnosed, illustrated report. therefore than currently known. diagnostic tools described here will help hence design disease management strategies. breeding should developed identify sources natural resistance, even family members. authors thankful International Foundation Science (grant 1-1-C-6140-1) Regional Universities Forum Capacity building financial support.