Biotype‐specific expression of dsRNA in the sweetpotato whitefly

Abstract

This study was conducted to evaluate the effect of two different biotypes of the sweetpotato whitefly, Bemisia tabaci (Gennadius), on the induction of squash silverleaf (SSL), and to determine if double‐stranded RNA (dsRNA) occurs in geographically remote populations of the two biotypes. Recently collected B‐biotype whiteflies from Florida, Arizona, Mississippi, and Texas (SPW‐B) all contained a 7.0 kb dsRNA molecule. Kb dsRNA molecule. Laboratory colonies of A‐biotype whiteflies that were originally collected in 1981 from cotton in Arizona and California did not contain the 7.0 Kb dsRNA. When the two biotypes were compared only the SPW‐B induced rapid onset, grade 5, SSL. DsRNA similar to that found in adult SPW‐B was concentrated in whitefly nymphs, but host plant leaf tissue did not contain any consistent dsRNA molecules. SPW‐A only induced low‐grade SSL and progeny of SPW‐A that were fed on pumpkin plants displaying SSL did not acquire the ability to express dsRNA or induce SSL. Our data suggest that dsRNA is not directly involved in the induction of SSL and that SSL is a host‐specific response to a feeding injury induced by B‐biotype whiteflies. The origin and source of the 7.0 Kb dsRNA molecule remains enigmatic but its expression is constant in the whitefly biotype that is responsible for the induction of SSL and several other plant disorders in the U.S.

Developmental Anatomy of Zucchini Leaves with Squash Silverleaf Disorder caused by the Silverleaf Whitefly

“…because there is no supporting evidence. Specifically, no doublestranded RNA has been detected in the affected leaves (Cohen et al, 1992;Jimenez et al, 1994;Yokomi et al, 1990). Further, there was no transmission of SSL from SSL-affected leaves grafted to whitefly-free plants and no mechanical transmission (Yokomi et al, 1990).…”

Possible Involvement of Altered Gibberellin Metabolism in the Induction of Tomato Irregular Ripening in Dwarf Cherry Tomato by Silverleaf Whitefly

“…In addition, fruit exhibit white or yellow tissues internally (Maynard andCantliffe 1989, Schuster et al 1990). Jimenez et al (1994) reported that the TIR is a host-specific disorder induced by the SLW, but the mechanism(s) of symptom development has not been specifically identified. Yokomi et al (1995) reported that the squash silverleaf (SSL) disorder induced by the feeding of SLW on Curcubita pepo L. results from an alteration of normal plant hormone production.…”