Citrus Variegated Chlorosis: Detection of Xylella fastidiosa in Symptomless Trees

Abstract

Xylella fastidiosa has been associated with citrus variegated chlorosis (CVC) by electron microscopy and serology using antisera to isolates of X. fastidiosa other than citrus. Antiserum has now been developed against X. fastidiosa isolated from CVC-affected citrus. This antiserum has been used to develop a sensitive, reliable serological assay based on a modification of dot immunobinding assays previously reported, coupled with western blotting, to detect X. fastidiosa in CVC affected trees. The procedure detects X. fastidiosa even in CVC-inoculated trees even before they develop symptoms, in some non-symptomatic trees in groves affected by CVC, and in healthy appearing sectors of trees which are showing CVC symptoms in other sectors. Bacteria were not detected in many healthy appearing trees from groves in non-CVC affected areas or in healthy greenhouse plants. This sensitive serological assay was developed to better enable screening of symptomless CVC-affected nursery plants and budwood source trees to reduce the possible spread of CVC via infected nursery materials.Index words. Xylem-limited bacteria, dot immunobinding assay, western blotting assay.

Eficiência de transmissão de >i<Xylella fastidiosa>/i< por cigarrinhas (Hemiptera, Cicadellidae) em >i<Citrus sinensis>/i< (L.) Osbeck e >i<Coffea arabica>/i< L.

“…O ELISA (Raju et al, 1983;Yonce & Chang, 1987) e o DIBA (Beretta et al, 1993b) têm sido amplamente desenvolvidos, mas apresentam baixa sensibilidade (Nomé et al, 1980) para detectar baixas populações de X. fastidiosa que ocorrem em algl..lmaS espécies de plantas, além do problema de detecção de falsos positivos (Hill & Purcell, 1995a e b). Mesmo assim, Leu et al (1998) desenvolveram anticorpos capazes de revelar diferenças serológícas entre estirpes de X. fastidiosa com resultados similares aos obtidos por análises de RAPD.…”