Roberts, Ronel


Publications
7

Update and Validation of the 16S rDNA qPCR Assay for the Detection of Three ‘Candidatus Liberibacter Species’ Following Current MIQE Guidelines and Workflow

Citation
Osman et al. (2023). PhytoFrontiers™ 3 (1)
Names
Ca. Liberibacter asiaticus Liberibacter
Abstract
An updated real-time multiplex quantitative polymerase chain reaction (qPCR) assay was designed and validated for the simultaneous detection of three ‘ Candidatus Liberibacter species’ (CLsp), ‘ Ca. Liberibacter asiaticus’ (CLas), ‘africanus’ (CLaf), and ‘americanus’ (CLam), associated with the huanglongbing disease of citrus. The multiplex assay was designed based on the qPCR assay published in 2006 by Li et al., considering all available CLsp 16S rRNA gene sequences in GenBank and the MIQE gu

A Review of the ‘Candidatus Liberibacter africanus’ Citrus Pathosystem in Africa

Citation
da Graça et al. (2022). Phytopathology® 112 (1)
Names
Ca. Liberibacter africanus
Abstract
It has been nearly 100 years since citrus growers in two distinct regions in the northern provinces of South Africa noticed unusual symptoms in their citrus trees, causing significant crop losses. They had no idea that these symptoms would later become part of an almost global pandemic of a disease called greening or huanglongbing (HLB). The rapid spread of the disease indicated that it might be caused by a transmissible pathogen, but it took >50 years to identify the causative agent as ‘Can

Genetic diversity of ‘Candidatus Liberibacter africanus’ in South Africa based on microsatellite markers

Citation
Roberts et al. (2021). European Journal of Plant Pathology 159 (2)
Names
Ca. Liberibacter africanus
Abstract
AbstractCitrus Greening disease (CG) in South Africa (SA) is associated with the fastidious bacterium ‘Candidatus Liberibacter africanus’ (Laf). It has been observed that Laf isolates obtained from different geographic localities in SA differed in the rate of transmission during grafting experiments leading to the hypothesis that genetic variation of Laf may exist in this country. To determine this, 167 Laf isolates obtained from Limpopo, North West, Mpumalanga and the Western Cape were subjecte

Resolution of the Identity of ‘Candidatus Liberibacter’ Species From Huanglongbing-Affected Citrus in East Africa

Citation
Roberts et al. (2017). Plant Disease 101 (8)
Names
Liberibacter
Abstract
‘Candidatus Liberibacter asiaticus’, the bacterium associated with citrus Huanglongbing (HLB), was reported from Uganda and tentatively from Tanzania, posing a threat to citriculture in Africa. Two surveys of citrus expressing typical HLB symptoms were conducted in Uganda, Kenya, and Tanzania to verify reports of ‘Ca. L. asiaticus’ and to assess the overall threat of HLB to eastern and southern African citrus production. Samples were analyzed for the presence of ‘Candidatus Liberibacter’ specie

Three novel lineages of ‘Candidatus Liberibacter africanus’ associated with native rutaceous hosts of Trioza erytreae in South Africa

Citation
Roberts et al. (2015). International Journal of Systematic and Evolutionary Microbiology 65 (Pt_2)
Names
Ca. Liberibacter africanus
Abstract
Greening disease of citrus in South Africa is associated with ‘Candidatus Liberibacter africanus’ (Laf), a phloem-limited bacterium vectored by the sap-sucking insect Trioza erytreae (Triozidae). Despite the implementation of control strategies, this disease remains problematic, suggesting the existence of reservoir hosts to Laf. The current study aimed to identify such hosts. Samples from 234 trees of Clausena anisata, 289 trees of Vepris lanceolata and 231 trees of Zanthoxylum capense were col