PREVALENCE OF VIRUS DISEASES, DISTRIBUTION AND CHARACTERIZATION OF VIRUSES INFECTING CUCURBIT CROPS IN SIX AGRO-ECOLOGICAL ZONES IN CÔTE D’IVOIRE

ABSTRACT

Viral diseases are a worldwide problem of cucurbits and a major limiting factor for they production. A field survey was conducted through six agro-ecological zones of Côte d’Ivoire during the dry and rainy seasons in 2014 to assess disease prevalence and severity, identify associated viruses, and evaluate the effect of temperature and growing seasons on virus diseases. 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 the new detected virus were also studied. High disease prevalence and severity was observed in both dry and rainy seasons. Significant difference (P < 0.05) was observed in rainy season varying between 0.6% and 56.8%. Cucumber mosaic virus (CMV), Zucchini yellow mosaic virus (ZYMV) and Papaya ringspot virus (PRSV) were detected out of five. CMV was more prevalent in dry season at an incidence of 31.5% whereas ZYMV was more prevalent in rainy season at an incidence of 34.3%. Pepo aphid borne yellows virus (PABYV) was detected by RT-PCR in Côte d’Ivoire as a Polerovirus based on the sequence similarity and phylogenetic analyses. CMV was detected at significantly enhanced levels in plants when co-infected with ZYMV; plant height was reduced compared to the single infection at 20°C and 25°C. During growing seasons, high incidence and severity were recorded with the highest mean disease severity in growing season 2. It is concluded that co-infection with ZYMV enhance the titer of CMV, which could have epidemiological significance.