Members of the Closteroviridae and Potyviridae families of the plant positive-strand RNA viruses encode one or two papain-like leader proteinases. In addition to a C-terminal proteolytic domain, each of these proteinases possesses a nonproteolytic N-terminal domain. We compared functions of the several leader proteinases using a gene swapping approach. The leader proteinase (L-Pro) of Beet yell...

Figure 1 Figure 2 Citrus fruits are traditional agricultural products in Egypt. Citrus volkameriana is the best rootstock for growing citrus in Egypt’s desert areas (newly reclaimed land). It is far superior to other rootstocks used in Egypt in its resistance to Citrus tristeza virus as well as its tolerance to drought. Constraints to fruit production are mainly related to tree decline caused b...

The 2000 x 11 nm long bipolar flexuous filamentous particles of Citrus tristeza virus (CTV) (genus Closterovirus, family Closteroviridae) (Figure 1) contain a single-stranded positive-sense RNA genome of 19.3 kb, which is encapsidated in two different capsid proteins that coat the opposite ends of the virions [1, 2]. CTV is the largest identified RNA virus infecting plants and the second larges...

Raspberry mosaic is one of the most important viral diseases of raspberry. Four virus and virus-like agents, two of which are poorly characterized, have been implicated in the disease complex based on symptom development in Rubus indicators. Three novel viruses were identified in a red raspberry plant that caused typical raspberry mosaic symptoms when grafted onto indicators. This communication...

The Citrus tristeza virus (CTV) strains present in an area can determine the type and severity of disease produced. Using real time RT-qPCR, we screened a series of representative samples collected throughout Florida from 1964 to 2002 for CTV strain presence. We found that contrary to previous reports, the historical samples were infected with both the T30 and T36 strains, the latter often at l...

Tristeza, caused by Citrus tristeza virus (CTV), has long been present in Florida but outbreaks of decline on sour orange rootstock were occasional events until the late 1970s. Sour orange rootstock was valued for the high quality of fruit produced and was widely used because of its tolerance of citrus blight, a disease of unknown etiology. Research was directed towards the selection and screen...

Citrus tristeza virus (CTV) is a phloem-limited virus whose natural host range is restricted to citrus and related species. Although the virus has killed millions of trees, almost destroying whole industries, and continually limits production in many citrus growing areas, most isolates are mild or symptomless in most of their host range. There is little understanding of how the virus causes sev...

Fourier transform infrared (FTIR) spectroscopy has the ability to quickly identify the presence of specific carbohydrates in plant materials. The presence of the disease huanglongbing (HLB) in the leaves of infected citrus plants has a distinctive spectrum that can be used to distinguish an infected plant from a healthy plant. However, many citrus diseases display similar visible symptoms and a...

Background and Aims: Plant certification programs need reliable, fast, cheap and sensitive methods for detection of systemic pathogens with special interest in virus and viroid detection. Reverse transcriptase-polymerase chain reaction (RT-PCR) has been documented as an alternative assay for certification of plant propagating materials. The main object of the present study was the optimization ...

Citrus Tristeza disease, caused by CTV (Citrus tristeza virus), committs citrus plantations around the world and specifically attacks phloem tissues of the plant. The virus exists as a mixture of more or less severe variants, which may or may not cause symptoms of Tristeza. The objective of this study was to analyze the changes caused by CTV in the proteome of stems of sweet orange, as well as ...