Tomato spotted wilt virus Can Infect Resistant Tomato when Western Flower Thrips Inoculate Blossoms.

Tomato spotted wilt is a major disease of crops worldwide. Resistant cultivars carrying the Sw-5 allele for resistance to tomato spotted wilt disease (TSW) provide the most effective control method in tomato (Solanum lycopersicum). However, infections of fruit on Sw-5+ tomato plants suggest the virus resistance may not be fully expressed in blossoms or developing fruit. The objective of this study was to determine if the thrips vector, the western flower thrips (Frankliniella occidentalis), can transmit non-resistance breaking Tomato spotted wilt virus (TSWV) isolates when confined to blossoms on plants with and without the Sw-5 resistance allele. Twenty-one percent of 33 Sw-5+ plants inoculated by adult thrips feeding on blossom clusters or small fruit developed infections in the reproductive tissue, whereas 68% of 25 Sw-5- plants developed infections. Systemic infections also occurred following inoculation of blossoms in host genotypes with and without Sw-5. These results were further supported by field experiments that showed high proportions of infected fruit as well as a limited infection of foliage on the same stem as the infected fruit in Sw-5+ plants when F. occidentalis were abundant in blossoms. These findings help to explain observations of abundant late season infections of Sw-5 cultivars in commercial plantings and suggest that management of F. occidentalis infestations during the bloom period may be important for effective management of TSWV in susceptible tomato cultivars as well as cultivars expressing the Sw-5 allele for TSW resistance.

Analysis of human interferon-alpha gene promoters by multiple sequence alignment.

A map of conserved motifs within 11 human interferon-alpha gene promoters was developed using multiple sequence alignment. Multiple sequence alignment revealed the highly conserved structure of the virus-response element and a second region immediately upstream of the tata box. Homolog analysis indicated six families of potential promoter elements: (1) tata boxes, (2) GTATGT motifs, (3) virus-response elements, (4) distal putative interferon regulatory factor binding sites, (5) proximal putative interferon regulatory factor binding sites, and (6) TG sequences. On the basis of conserved promoter elements, a theoretical model of human interferon-alpha gene promoter organization was advanced. Transcriptional regulation of human interferon-alpha gene expression is controlled by a tata box and four regulatory domains. Experimental verification is necessary to confirm the predicted transcriptional control sequences. Proposed experimentation will generate insight into the differential transcriptional regulation of human interferon-alpha gene expression.