Polymorphism of viral dsRNA in Xanthophyllomyces dendrorhous strains isolated from different geographic areas

Abstract

Background: Strains of the astaxanthin producing yeast Xanthophyllomyces dendrorhous have been isolated from different cold regions around the earth, and the presence of double stranded RNA (dsRNA) elements was described in some isolates. This kind of viruses is widely distributed among yeasts and filamentous fungi and, although generally are cryptic in function, their studies have been a key factor in the knowledge of important fungi. In this work, the characterization and genetic relationships among dsRNA elements were determined in strains representatives of almost all regions of the earth where X. dendrorhous have been isolated.

Molecular characterization of totiviruses in Xanthophyllomyces dendrorhous

“…The existence of VLPs and extrachromosomal dsRNA elements with estimated lengths of 5 (L1), 3.7 (L2), 1.4 (M), 0.9 (S1) and 0.8 (S2) kbp have been described in Xanthophyllomyces dendrorhous (formerly Phaffia rhodozyma ) [12-15]. This basidiomycetous yeast has been isolated from cold climate areas around the world [16-20] and is currently one of the most promising sources of astaxanthin, a biotechnologically important carotenoid pigment [21,22].…”

The inter-generic fungicidal activity of Xanthophyllomyces dendrorhous

“…No fungicidal activity of N. fulvescens against other Nadsonia species was detected. The mycocinogenic strains of X. dendrorhous have a high degree of polymorphism in dsRNAs with no common elements; one X. dendrorhous strain and the P. rhodozyma strain have no dsRNA (Baeza et al, 2009). Therefore, the dsRNAs cannot encode for the fungicidal activity of X. dendrorhous against R. sloffiae, R. minuta, and K. apiculata.…”

“…Double-stranded RNA elements have been found in several members of the Cystofilobasidiales clade and associated fungicidal activity has been described (Karamysheva et al, 1993;Pfeiffer et al, 1998Pfeiffer et al, , 2004bFell et al, 1999;Golubev et al, 2002Golubev et al, , 2003 in each strain except for the astaxanthin-producing yeast Xanthophyllomyces dendrorhous. The EGEs described in this yeast are variable, and the strains can have dsRNA elements, linear dsDNA plasmids or both; in Phaffia rhodozyma (the imperfect phase of X. dendrorhous), the presence of only dsDNA plasmids has been reported (Castillo and Cifuentes, 1994;Pfeiffer et al, 1996Pfeiffer et al, , 2001Kucsera et al, 2000;Baeza et al, 2009). In previous studies about the potential functions of dsRNAs, a minor effect on the reproduction and fitness of X. dendrorhous was observed, and the results regarding fungicidal activity were inconsistent (Castillo and Cifuentes, 1994;Pfeiffer et al, 1996Pfeiffer et al, , 2001.…”

“…Most strains of X. dendrorhous have dsRNA elements that vary in number and size (Castillo and Cifuentes, 1994;Pfeiffer et al, 1996;Baeza et al, 2009). From strain UCD 67-385, which has four dsRNAs of 5.0 (L1), 3.7 (L2), 0.9 (S1), and 0.8 (S2) kb, we previously obtained a clone lacking the S2 dsRNA [385(S2)-40] by treatment with the peptidyl transferase inhibitor anisomycin (Baeza et al, 2009).…”

Characterization of virus-like particles and identification of capsid proteins in Xanthophyllomyces dendrorhous

“…Recently, three putative totiviruses called XdV-L1A, XdV-L1B, and XdV-L2 were identified in the strain UCD 67-385 of X. dendrorhous, and also two dsRNA molecules (XdRm-S1 and XdRm-S2) that could be satellite viruses [14]. The XdV-L1A and XdV-L1B viruses are found in almost all dsRNAharboring strains of X. dendrorhous, while the presence of L2-and minor size dsRNAs is quite variable among isolates from different regions of the earth [14,15]. The presence of virus-like particles (VLPs) has been reported in some strains of X. dendrorhous and the encapsidation of dsRNAs into VLPs has been suggested according to results obtained from RNase protection assays [14].…”