Selection of host plants for vector transmission assays of citrus variegated chlorosis strains of Xylella fastidiosa subsp. pauca

Abstract

The vector-borne bacterium Xylella fastidiosa subsp. pauca is the etiological agent of important plant diseases, such as citrus variegated chlorosis (CVC). Biological studies are relatively scarce for CVC, in part because citrus is a low titer woody host, in which X. fastidiosa has a long incubation period and low transmission efficiency by vectors. To optimize transmission bioassays, this study was conducted to: i) identify herbaceous plants that allow rapid multiplication and systemic colonization of CVC strains; and ii) evaluate the herbaceous hosts for feeding and survival of the sharpshooter vector, Bucephalogonia xanthophis (Berg), and as indicators of infection after vector inoculation. Mechanical inoculations showed systemic colonization of X. fastidiosa in seven plant species, with higher rates of infection mainly in Catharanthus roseus. The lowest vector mortality was observed on C. roseus, Medicago sativa and Ocimum basilicum. The highest feeding rate was verified on O. basilicum, followed by M. sativa and C. roseus. Infections after vector inoculation were detected in C. roseus, M. sativa, O. basilicum and S. americanum. Among the plant species tested, C. roseus proved to be the most suitable experimental plant for transmission assays with CVC strains of X. fastidiosa subsp. pauca.