Incidence and phylogeny of viruses infecting cucurbit crops in KwaZulu-Natal, Republic of South Africa

Abstract

Virus infections on cucurbits often result in substantial losses. Surveys were conducted throughout the province of KwaZulu-Natal (KZN) in the Republic of South Africa (RSA) during the 2011–2013 growing seasons to identify cucurbit-infecting viruses. Viruses were detected on sampled leaves displaying virus-like symptoms using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and reverse transcription polymerase chain reaction (RT-PCR). The phylogenetic relationships of all detected viruses were also studied. Cucumber mosaic virus (CMV), Beet pseudo-yellows virus (BPYV), Zucchini yellow mosaic virus (ZYMV), Moroccan watermelon mosaic virus (MWMV) and a Polerovirus were detected at an incidence of 3.48%, 10%, 13.04%, 48.70% and 41.67% respectively. Phylogenetic analyses identified CMV isolates as members of the Subgroup IA of the CMV lineage and ZYMV isolates as members of the subgroups AI and AII of the of ZYMV lineage. MWMV isolates formed a distinct clade within the Southern African group of the MWMV lineage. Polerovirus isolates were identified as Pepo aphid-borne yellows virus (PABYV) based on the sequence similarity and phylogenetic analyses. The information generated from this study will contribute towards the development of effective management strategies against viruses infecting cucurbits in KZN.