Characterization of Sphaeropsis sapinea Isolates from South Africa, Mexico, and Indonesia

Abstract

Post-hail-associated dieback of Pinus patula and P. radiata trees, induced by Sphaeropsis sapinea (=Diplodia pinea), is a common and important disease in commercial pine plantations. Two morphotypes, A and B, have been described for this fungus based on differences in cultural characteristics, conidial morphology, and virulence among isolates from the north central United States. The existence of the two described morphotypes was later verified through the use of random amplified polymorphic DNA (RAPD) analyses, and the morphotypes were designated as the A and B RAPD marker groups. The objective of this study was to characterize a set of S. sapinea isolates from South Africa, Indonesia, and Mexico using RAPD analysis and DNA sequencing of the internal transcribed spacer (ITS) region of the ribosomal DNA operon. Sizes of conidia and culture morphology were, furthermore, used to compare the three groups of S. sapinea isolates that emerged from the RAPD analysis. Two of the RAPD groups included isolates from the United States, representing the A and B morphotypes, while the third RAPD group accommodated Indonesian and one Mexican isolate. ITS sequences of all the S. sapinea isolates were highly homologous and resolved only the A and B RAPD groups. The ITS sequences of the isolates in the third RAPD group were the same as those of the A RAPD group. Conidia of isolates representing the A and B morphotypes were approximately the same size, but those of the third RAPD group were significantly longer. RAPD analysis enabled us to identify a third group of S. sapinea that is different from the well-recognized A and B groups. Isolates in this third RAPD group also have a distinct morphological characteristic and thus represent a third discrete morphological group, which we refer to as the C morphotype of S. sapinea.

Comparison of genotypic diversity in native and introduced populations of Sphaeropsis sapinea isolated from Pinus radiata

“…The pathogenicity of representative isolates from VC groups, S1-5, was tested using an apple technique (Fulbright 1984), described previously as useful to assess the relative aggressiveness of Sphaeropsis sapinea isolates by de Wet et al (2000). A cork borer (10 mm) was used to make a wound 5 mm deep on one side of large Granny Smith apples.…”

METODOLOGIA DE AVALIAÇÃO DA AGRESSIVIDADE DE ISOLADOS DE Sphaeropsis sapinea A Pinus taeda

“…De Wet et al (2000) descreveram dois morfotipos inicialmente para S. sapinea (A e B), com base nas características das culturas, textura da parede dos conídios, confirmados através do uso de ferramentas moleculares, como RAPD e sequenciamento da região ITS do RNA operon. Os autores relataram também um terceiro grupo, denominado morfotipo C, obtido do México e Indonésia, com base nas medidas conidiais e marcadores RAPD.…”

Geographic isolation of Diplodia scrobiculata and its association with native Pinus radiata

“…However, only D. pinea is known to have been introduced to southern hemisphere pine plantations (Swart et al 1991, Stanosz et al 1999, de Wet et al 2000, Burgess & Wingfield 2001, Burgess et al 2001a, Burgess et al 2004. The origin of D. pinea populations in exotic plantations was impossible to determine due to the lack of equivalent unique alleles in native populations (Burgess et al 2004).…”

“…and the relatively recent discovery of its endophytic nature suggests it is present in pines wherever they grow (Petrini & Fisher 1988, Stanosz et al 1995, Smith et al 1996, Burgess, Wingfield & Wingfield 2001a, Flowers et al 2001), although it is not known if it is native to all regions or if it has been introduced by the activities of man. D. pinea was thought to be a single species consisting of at least three morphotypes (Palmer, Stewart & Wingfield 1987, Hausner et al 1999, Stanosz, Swart & Smith 1999, de Wet et al 2000, Burgess, Wingfield & Wingfield 2001b, Zhou, Smith & Stanosz 2001. However, a recent study using multiple gene genealogies, has led to the description of a new species, D. scrobiculata, to accommodate the 'B ' morphotype (de Wet et al 2003).…”