Efficacy of Bioindexing for Graft-Transmissible Citrus Pathogens in Mixed Infections.

Biological indexing for graft-transmissible pathogens of citrus in the presence of additional pathogens was investigated. The probability for symptom expression, the efficacy of the bio-indexing tests, and the number of citrus indicators required for pathogen detection were statistically evaluated. Multiple infections did not preclude symptom expression or reduce the diagnostic efficacy of the primary indexing hosts for Citrus tristeza virus (CTV), Citrus psorosis virus (CPsV), and Citrus tatter leaf virus (Apple stem grooving virus).

Finger Imprint of Poncirus trifoliata: A Specific Interaction of a Viroid, a Host, and Irrigation.

The unusual symptom, "finger imprint", described exclusively on Poncirus trifoliata, has been reported in only a single field trial investigating the effects of citrus viroids on crop performance. With this, the question has persisted whether the observed growth abnormality was a disease symptom induced by Citrus viroid IIIb (CVd-IIIb) or a consequence of mechanical damage caused by the handling of young trees during propagation or cultural practices in the field. The recurrence of finger imprint symptoms on trees after 5 years in the field in which no abnormal growth features were previously noted now supports the proposition of a viroid-induced disease.

Characterization of citrus tristeza virus subgenomic RNAs in infected tissue.

Citrus tristeza virus (CTV) specific RNAs extracted from infected citrus tissue were analyzed by Northern blot hybridization. RNAs were characterized by size and identified using cDNA probes specific to nine open reading frames (ORFs) identified by the analysis of sequence obtained from cDNA clones of the T36 isolate of CTV. Sequence specific cDNA probes identified the genomic RNA as well as subgenomic RNAs representing the p33, p65, p61, p27, p25, p18, p13, p20, and p23 ORFs in extracts of total or double-stranded RNA (dsRNA) isolated from infected tissue.

Complete sequence of the citrus tristeza virus RNA genome.

The sequence of the entire genome of citrus tristeza virus (CTV), Florida isolate T36, was completed. The 19,296-nt CTV genome encodes 12 open reading frames (ORFs) potentially coding for at least 17 protein products. The 5'-proximal ORF 1a starts at nucleotide 108 and encodes a large polyprotein with calculated MW of 349 kDa containing domains characteristic of (from 5' to 3') two papain-like proteases (P-PRO), a methyltransferase (MT), and a helicase (HEL).

Screening of the closterovirus genome by degenerate primer-mediated polymerase chain reaction.

The genome of beet yellows virus (BYV), the type representative of the closterovirus group, encodes a homologue of the cellular heat-shock protein (HSP) 70 family. A pair of degenerate primers targeted to motifs A and E, which are highly conserved in HSP70s, was synthesized. Genomes of several definite and possible members of the closterovirus group were screened for the presence of the HSP70 gene with PCR using these degenerate primers.

Production, characterization, and applications of monoclonal antibodies reactive with soybean nodule xanthine dehydrogenase.

Seven monoclonal antibodies were produced against soybean nodule xanthine dehydrogenase, an enzyme involved in ureide synthesis. Specificity of the seven monoclonal antibodies for xanthine dehydrogenase was demonstrated by immunopurifying the enzyme to homogeneity from a crude nodule extract using antibodies immobilized to Sepharose 4B beads. Each monoclonal antibody was covalently bound to Sepharose 4B beads for the preparation of immunoaffinity columns for each antibody.

A barley lectin that binds free amino sugars. I. Purification and characterization.

A lectin was isolated from barley seen which bound the coat glycoprotein of barley stripe mosaic virus (Type strain) and precipitated the virus from solution. Purification of the barley lectin was achieved by fractionation with ammonium sulfate and successive column chromatography on DEAE cellulose and cellulose phosphate. The barley lectin was homogeneous as ascertained by polyacrylamide gel electrophoresis, isoelectric focusing, and from immunochemical tests.