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Fusarium zanthoxyli and F. continuum are sister taxa that are the etiological agents of canker disease of prickly ash (Zanthoxylum bungeanum) in northern China. These two pathogens, together with F. torreyae, the causal agent of canker disease of the critically endangered conifer Florida torreya (Torreya taxifolia) from northern Florida and southwestern Georgia, constitute a novel clade, the F. torreyae species complex. To assess their reproductive mode, a polymerase chain reaction (PCR) assay targeting the MAT1-1 and MAT1-2 idiomorphs was designed and validated, using MAT sequences mined from the whole-genome sequence of the three F. torreyae clade pathogens and several closely related fusaria. Results of the MAT idiomorph PCR assay indicated that isolates of the three pathogens were MAT1-1 or MAT1-2. When MAT1-1 and MAT1-2 isolates of each species were crossed on carrot agar, all of the F. zanthoxyli (N = 30) and F. continuum (N = 3) isolates tested were female fertile, yielding mature perithecia with viable ascospores. By comparison, only one pairing of the five different isolates of F. torreyae produced perithecia; however, the majority of the asci in this cross aborted or produced fewer than eight ascospores. Of the three temperatures tested (i.e., 22, 25, and 27 C), the optimal temperature for perithecium production was 22-25 C in F. zanthoxyli and 25 C in F. continuum and F. torreyae. Ascospore progeny from three separate crosses of F. zanthoxyli and F. continuum and one cross of F. torreyae were genotyped to assess whether they were the products of genetic recombination and sexual reproduction. Genotyping of 34-40 progeny from the F. zanthoxyli and F. continuum crosses confirmed that they were the products of sexual reproduction. However, only 36% of the progeny in the F. torreyae cross were recombinant, which was roughly half of the nonparental progeny expected with three markers segregating. [ABSTRACT FROM AUTHOR]

Setosphaeria rostrata, a common plant pathogen causing leaf spot disease, affects a wide range of plant species, mainly grasses. Fungi were isolated from brown spots on rice leaves throughout Peninsular Malaysia, and 45 isolates were identified as Setosphaeria rostrata. The isolates were then characterized using morphological and molecular approaches. The mating type was determined using PCR amplification of the mating type alleles, and isolates of opposite mating types were crossed to examine sexual reproduction. Based on nuclear ribosomal DNA ITS1-5.8S-ITS2 region (ITS) and beta-tubulin (BT2) sequences, two phylogenetic trees were constructed using the maximum likelihood method; S. rostrata was clustered in one well-supported clade. Pathogenicity tests showed that S. rostrata isolates are pathogenic, suggesting that it is the cause of the symptoms. Mating-type analyses indicated that three isolates carried the MAT1-1 allele, and the other 42 isolates carried MAT1-2. After isolates with opposite mating types were crossed on Sach's medium and incubated for 3 wk, six crosses produced pseudothecia that contained eight mature ascospores, and 12 other crosses produced numerous pseudothecia with no ascospores. To our knowledge, this is the first report on S. rostrata isolated from leaf spots on rice. [ABSTRACT FROM AUTHOR]

Isolations from the granulate ambrosia beetle, Xylosandrus crassiusculus (Coleoptera: Curculionidae: Scolydnae: Xyleborini), collected in Georgia, South Carolina, Missouri and Ohio, yielded an undescribed species of Ambrosiella in thousands of colony-forming units (CFU) per individual female. Partial sequences of ITS and 28S rDNA regions distinguished this species from other Ambrosiella spp., which are asexual symbionts of ambrosia beetles and closely related to Ceratocystis spp. Ambrosiella roeperi sp. nov. produces sporodochia of branching conidiophores with disarticulating swollen cells, and the branches are terminated by thick-walled aleurioconidia, similar to the conidiophores and aleurioconidia of A. xylebori, which is the mycangial symbiont of a related ambrosia beetle, X. compactus. Microscopic examinations found homogeneous masses of arthrospore-like cells growing in the mycangium of X. crassiusculus, without evidence of other microbial growth. Using fungal-specific primers, only the ITS rDNA region of A. roeperi was amplified and sequenced from DNA extractions of mycangial contents, suggesting that it is the primary or only mycangial symbiont of this beetle in USA. [ABSTRACT FROM AUTHOR]

The genus Metarhizium historically refers to green-spored asexual insect pathogenic fungi. Through culturing and molecular methods, Metarhizium has been linked to Metacordyceps sexual states. Historically fungal nomenclature has allowed separate names for the different life stages of pleomorphic fungi. However, with the move to one name for one fungus regardless of life stage, there is a need to determine which name is correct. For Metarhizium the situation is complicated by the fact that Metacordyceps sexual states are interspersed among additional asexual genera, including Pochonia, Nomuraea and Paecilomyces. Metarhizium has priority as the earliest available name, but delimiting the boundaries of this genus remains problematic. To clarify relationships among these taxa we have obtained representative material for each genus and established a molecular dataset of the protein-coding genes BTUB, RPB1, RPB2 and TEF. The resulting phylogeny supports Metarhizium combining the majority of species recognized in Metacordyceps as well as the green-spored Nomuraea species and those in the more recently described genus Chamaeleomyces. Pochonia is polyphyletic, and we restrict the definition of this genus to those species forming a monophyletic clade with P. chlamydosporia, and the excluded species are transferred to Metapochonia gen. nov. ft is our hope that this unified concept of sexual and asexual states in Metarhizium will foster advances in communication and understanding the unique ecologies of the associated species. [ABSTRACT FROM AUTHOR]

The genus Ulocladium is thought to be strictly asexual. Mating-type (MAT) loci regulate sexual reproduction in fungi and their study may help to explain the apparent lack of sexual reproduction in Ulocladium. We sequenced the full length of two MAT genes in 26 Ulocladium species and characterized the entire M A T idiomorphs plus flanking regions of Ulocladium botrytis. The MAT1-1 ORF encodes a protein with an alpha-box motif by the MAT1-1-1 gene and the MAT1-2 ORF encodes a protein with an HMG box motif by the MAT1-2-1 gene. Both MAT1-1-1 and MAT1-2-1 genes were detected in a single strain of every species. Moreover, the results of RT-PCR revealed that both MAT genes are expressed in all 26 Ulocladium species. This demonstrates that MAT genes of Ulocladium species might be functional and that they have the potential for sexual reproduction. Phylogenies based on MAT genes were compared with GAPDH and Alt a 1 phylograms in Ulocladium using maximum parsimony (MP) and Bayesian analysis. The MAT genealogies and the non-MAT trees displayed different topologies, indicating that M A T genes are unsuitable phylogenetic markers at the species level in Ulocladium . Furthermore, the conflicting topologies between MAT1-1-1 and MAT1-2-1 phylogeny indicate separate evolutionary events for the two M A T genes. However, the intergeneric phylogeny of four closely allied genera (Ulocladium, Altemaria, Cochliobolus, Stemphylium) based on M A T alignments demonstrated that M A T genes are suitable for phylogenetic analysis among allied genera. [ABSTRACT FROM AUTHOR]

Phytophthora capsici and the closely related Phytophthora tropicalis infect different hosts that have documented overlapping geographical distributions. Phytophthora capsici attacks annual vegetable hosts whereas P. tropicalis has been recovered from woody perennial hosts. Our objective was to test whether interspecific hybridization is possible and to characterize the resulting progeny. Crosses were made between P. capsici (LT263) from pumpkin to P. tropicalis from rhododendron (LT232) and to P. tropicalis from Theobroma cacao (LT12). The wild type isolates were analyzed for mitochondrial and nuclear DNA sequence diversity and progeny were tested for mating type (MT), AFLP marker profiles and mitochondrial DNA haplotype (mtDNA type). All oospore progeny from LT263 x LT12 were identical to LT263 whereas progeny from LT263 x LT232 were parental as well as hybrid. Hybrid progeny had either one or the other parent mtDNA type and there was no correlation between MT and mtDNA type. Attempts to generate an F9 population from the hybrids proved unsuccessful while a backcross to the P. capsici parent produced hybrid progeny. These results demonstrate that apomixis might play a significant role in species separation and that hybridization between P. capsici and P. tropicalis is possible beyond the F1 generation. [ABSTRACT FROM AUTHOR]

The presence of zygospores in the genus Orphella is newly described. We found zygospores in three species of the genus, O. catalaunica, O. coronata and O. helicospora, which are all the species of the genus known from the Iberian territory. Zygospores are associated with a heterothallic conjugating sexual process in O. coronata, whereas in O. catalaunica and O. helicospora, they form homothallically. In all instances, zygospores are consistently associated with an organized pattern of sterile cells, forming structures comparable to those present with asexual trichospores. We compare the ontogeny of Orphella zygospores with that found in the harpellid Genistellospora homothallica and discuss the possible close relationship of Orphella with Kickxellales (Zygomycetes). We report O. coronata in Spain for the first time, replacing all previous records of O. haysii. Results are supported with line drawings and photographs. [ABSTRACT FROM AUTHOR]