Incidence of RNA viruses infecting taro and tannia in East Africa and molecular characterisation of dasheen mosaic virus isolates.

Taro () and tannia ( sp.) plants growing in 25 districts across Ethiopia, Kenya, Tanzania and Uganda were surveyed for four RNA viruses. Leaf samples from 392 plants were tested for cucumber mosaic virus (CMV), dasheen mosaic virus (DsMV), taro vein chlorosis virus (TaVCV) and Colocasia bobone disease-associated virus (CBDaV) by RT-PCR.

A novel nepovirus causing a chlorotic fleck disease on common bean (Phaseolus vulgaris L.).

Two common bean leaf samples from Ethiopia that had shown chlorotic fleck and veinal mosaic symptoms but tested ELISA-negative for known viruses were mechanically transmitted to herbaceous hosts to obtain virus isolates ET-773/4 and ET-779. Virus purification from Chenopodium quinoa systemically infected with ET-773/4 yielded icosahedral particles measuring ~ 30 nm in diameter and containing a single capsid protein of ~ 58 kDa, suggesting a nepovirus infection. Analysis of nucleotide sequences generated from RNA1 and RNA2 of the isolates indicated that they represent a distinct virus species in the genus Nepovirus.

A Review of Viruses Infecting Yam ( spp.).

Yam is an important food staple for millions of people globally, particularly those in the developing countries of West Africa and the Pacific Islands. To sustain the growing population, yam production must be increased amidst the many biotic and abiotic stresses. Plant viruses are among the most detrimental of plant pathogens and have caused great losses of crop yield and quality, including those of yam.

Molecular characterisation of a putative new polerovirus infecting pumpkin (Cucurbita pepo) in Kenya.

Next-generation sequencing of RNA extracted from a pumpkin plant with mosaic symptoms in Kenya identified the presence of a polerovirus sequence closely related to pepo aphid-borne yellows virus (PABYV). The near-complete polerovirus sequence comprised 5,810 nucleotides and contained seven putative open reading frames (ORFs) with a genome organisation typical of poleroviruses. BLASTp analysis of the translated sequences of ORFs 0, 1 and 2 revealed that their amino acid sequences differed by more than 10% from the corresponding protein sequences of other poleroviruses.

Assessment and optimization of rolling circle amplification protocols for the detection and characterization of badnaviruses.

The genus Badnavirus is characterized by members that are genetically and serologically heterogeneous which presents challenges for their detection and characterization. The presence of integrated badnavirus-like sequences in some host species further complicates detection using PCR-based protocols. To address these challenges, we have assessed and optimized various RCA protocols including random-primed RCA (RP-RCA), primer-spiked random-primed RCA (primer-spiked RP-RCA), directed RCA (D-RCA) and specific-primed RCA (SP-RCA).

Characterization of a novel member of the family Caulimoviridae infecting Dioscorea nummularia in the Pacific, which may represent a new genus of dsDNA plant viruses.

We have characterized the complete genome of a novel circular double-stranded DNA virus, tentatively named Dioscorea nummularia-associated virus (DNUaV), infecting Dioscorea nummularia originating from Samoa. The genome of DNUaV comprised 8139 bp and contained four putative open reading frames (ORFs). ORFs 1 and 2 had no identifiable conserved domains, while ORF 3 had conserved motifs typical of viruses within the family Caulimoviridae including coat protein, movement protein, aspartic protease, reverse transcriptase and ribonuclease H.

Characterization of an Australian isolate of taro bacilliform virus and development of an infectious clone.

The badnavirus taro bacilliform virus (TaBV) has been reported to infect taro (Colocasia esculenta L.) and other edible aroids in several South Pacific island countries, but there are no published reports from Australia. Using PCR and RCA, we identified and characterized an Australian TaBV isolate.

Complete genome sequence of a novel zantedeschia mild mosaic virus isolate: the first report from Australia and from Alocasia sp.

The complete genome of an Australian isolate of zantedeschia mild mosaic virus (ZaMMV) causing mosaic symptoms on Alocasia sp. (designated ZaMMV-AU) was cloned and sequenced. The genome comprises 9942 nucleotides (excluding the poly-A tail) and encodes a polyprotein of 3167 amino acids.