Characterisation of Phomopsis spp. associated with die-back of rooibos (Aspalathus linearis) in South Africa

Abstract

Die-back of rooibos (Aspalathus linearis) causes substantial losses in commercial Aspalathus plantations in South Africa. In the past, the disease has been attributed to Phomopsis phaseoli (teleomorph: Diaporthe phaseolorum). Isolates obtained from diseased plants, however, were highly variable with regard to morphology and pathogenicity. The aim of the present study was thus to identify the Phomopsis species associated with die-back of rooibos. Isolates were subjected to DNA sequence comparisons of the internal transcribed spacer region (ITS1, 5.8S, ITS2) and partial sequences of the translation elongation factor-1 alpha gene. Furthermore, isolates were also compared in glasshouse inoculation trials on 8-mo-old potted plants to evaluate their pathogenicity. Five species were identified, of which D. aspalathi (formerly identified as D. phaseolorum or D. phaseolorum var. meridionalis) proved to be the most virulent, followed by D. ambigua, Phomopsis theicola, one species of Libertella and Phomopsis, respectively, and a newly described species, P. cuppatea. A description is also provided for D. ambigua based on a newly designated epitype specimen.

Fungal Scleral Keratitis Caused by Phomopsis phoenicicola

“…The Species Fungorum database website (http://www.speciesfungorum.org/Index .htm), coordinated by CABI Bioservices, has data collected on more than 900 Phomopsis spp. The identification of Phomopsis by using only morphological characteristics is difficult, and it is now recognized that host is of minor importance (12 rently, identification is based on molecular phylogenies, especially using sequences of the ITS region of rDNA (15,21). Therefore, we agree with several authors that molecular techniques are the most promising approach for the identification of Phomopsis spp.…”

One stop shop: backbones trees for important phytopathogenic genera: I (2014)

“…Ex-type cultures are available for less than 100 species known despite the large number of Ex-type (ex-epitype) strains are bolded and marked with an * and voucher stains are bolded species listed in databases and literature. The delimitation of species within the genus Diaporthe improved once DNA sequence data were incorporated (Castlebury and Mengistu 2006;Van Rensburg et al 2006;Santos et al 2010;Udayanga et al 2012bUdayanga et al , 2014a, since this facilitates obtaining detailed insight into complex evolutionary relationships.…”

“…Since the first molecular phylogenetic study in Diaporthe (Rehner and Uecker 1994), rDNA ITS, partial sequences of translation elongation factor 1-α (TEF) and mating type genes (MAT 1-1-1/1-2-1) have commonly been used in molecular phylogenetic studies in this genus (Van Niekerk et al 2005;Van Rensburg et al 2006;Santos et al 2010;Udayanga et al 2011;Sun et al 2012). Udayanga et al (2012a) used ITS, TEF, β-tubulin and CAL genes with a selected set of ex-type cultures and additional isolates to infer the phylogeny of the genus.…”

Specific boundaries between the causal agents of the soybean stem canker

“…The ITS region, on the other hand, was identical between D. aspalathi and D. phaseolorum var. meridionalis, as previously stated (Rensburg et al, 2006).…”

“…meridionalis. Based on nucleotide sequence data, cultural, phytopathological and morphological evidence, Rensburg et al (2006) Species identification in Diaporthe has been traditionally based on host specificity (Udayanga et al, 2011;. Few morphological characters can undoubtedly differentiate among taxa (Uecker, 1988).…”