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Background: Toxoplasma gondii is an opportunistic protozoan apicomplexan and obligate intracellular parasite that infects a wide range of animals and humans. Rhoptry proteins 5 (ROP5), ROP16, ROP18 and dense granules 15 (GRA15) are the important effectors secreted by T. gondii which link to the strain virulence for mice and modulate the host's response to the parasite. Little has been known about these molecules as well as GRA3 in type Chinese 1 strains that show polymorphism among strains of archetypical genotypes. This study examined the genetic diversity of these effectors and its correlated virulence in mice among T. gondii isolates from China. Results: Twenty-one isolates from stray cats were detected, of which 15 belong to Chinese 1, and 6 to ToxoDB #205. Wh6 isolate, a Chinese 1 strain, has an avirulent phenotype. PCR-RFLP results of ROP5 and ROP18 presented few variations among the strains. Genotyping of GRA15 and ROP16 revealed that all the strains belong to type II allele except Xz7 which carries type I allele. ROP16 amino acid alignment at 503 locus demonstrated that 17 isolates are featured as type I or type III (ROP16I/III), and the other 4 as type II (ROP16II). The strains investigated may be divided into four groups based on GRA3 amino acid alignment, and all isolates of type Chinese 1 belong to the μ-1 allele except Wh6 which is identical to type II strain. Conclusions: PCR-RFLP and sequence alignment analyses of ROP5, ROP16, ROP18, GRA3, and GRA15 in T. gondii revealed that strains with the same genotype may have variations in some of their key genes. GRA3 variation exhibited by Wh6 strain may be associated with the difference in phenotype and pathogenesis. [ABSTRACT FROM AUTHOR]

Previous studies have shown that our understanding of species diversity within Diaporthe (syn. Phomopsis) is limited. In this study, 49 strains obtained from different countries were subjected to DNA sequence analysis. Based on these results, eight new species names are introduced for lineages represented by multiple strains and distinct morphology. Twelve Phomopsis species previously described from China were subjected to DNA sequence analysis, and confirmed to belong to Diaporthe. The genus Diaporthe is shown to be paraphyletic based on multi-locus (LSU, ITS and TEF1) phylogenetic analysis. Several morphologically distinct genera, namely Mazzantia, Ophiodiaporthe, Pustulomyces, Phaeocytostroma, and Stenocarpella, are embedded within Diaporthe s. lat., indicating divergent morphological evolution. However, splitting Diaporthe into many smaller genera to achieve monophyly is still premature, and further collections and phylogenetic datasets need to be obtained to address this situation. [ABSTRACT FROM AUTHOR]

Background: Accurate delimitation of plant pathogenic fungi is critical for the establishment of quarantine regulations, screening for genetic resistance to plant pathogens, and the study of ecosystem function. Concatenation analysis of multi-locus DNA sequence data represents a powerful and commonly used approach to recognizing evolutionary independent lineages in fungi. It is however possible to mask the discordance between individual gene trees, thus the speciation events might be erroneously estimated if one simply recognizes well supported clades as distinct species without implementing a careful examination of species boundary. To investigate this phenomenon, we studied Colletotrichum siamense s. lat., which is a cosmopolitan pathogen causing serious diseases on many economically important plant hosts. Presently there are significant disagreements among mycologists as to what constitutes a species in C. siamense s. lat., with the number of accepted species ranging from one to seven. Results: In this study, multiple approaches were used to test the null hypothesis "C. siamense is a species complex", using a global strain collection. Results of molecular analyses based on the Genealogical Concordance Phylogenetic Species Recognition (GCPSR) and coalescent methods (e.g. Generalized Mixed Yule-coalescent and Poisson Tree Processes) do not support the recognition of any independent evolutionary lineages within C. siamense s. lat. as distinct species, thus rejecting the null hypothesis. This conclusion is reinforced by the recognition of genetic recombination, cross fertility, and the comparison of ecological and morphological characters. Our results indicate that reproductive isolation, geographic and host plant barriers to gene flow are absent in C. siamense s. lat. Conclusions: This discovery emphasized the importance of a polyphasic approach when describing novel species in morphologically conserved genera of plant pathogenic fungi. [ABSTRACT FROM AUTHOR]

Background: Maize is a major staple food crop globally and contains various concentrations of vitamins. Folates are essential water-soluble B-vitamins that play an important role as one-carbon (C1) donors and acceptors in organisms. To gain an understanding of folate metabolism in maize, we performed an intensive in silico analysis to screen for genes involved in folate metabolism using publicly available databases, followed by examination of the transcript expression patterns and profiling of the folate derivatives in the kernels of two maize inbred lines. Results: A total of 36 candidate genes corresponding to 16 folate metabolism-related enzymes were identified. The maize genome contains all the enzymes required for folate and C1 metabolism, characterized by highly conserved functional domains across all the other species investigated. Phylogenetic analysis revealed that these enzymes in maize are conserved throughout evolution and have a high level of similarity with those in sorghum and millet. The LC-MS analyses of two maize inbred lines demonstrated that 5-methyltetrahydrofolate was the major form of folate derivative in young seeds, while 5-formyltetrahydrofolate in mature seeds. Most of the genes involved in folate and C1 metabolism exhibited similar transcriptional expression patterns between these two maize lines, with the highest transcript abundance detected on day after pollination (DAP) 6 and the decreased transcript abundance on DAP 12 and 18. Compared with the seeds on DAP 30, 5-methyltetrahydrofolate was decreased and 5-formyltetrahydrofolate was increased sharply in the mature dry seeds. Conclusions: The enzymes involved in folate and C1 metabolism are conserved between maize and other plant species. Folate and C1 metabolism is active in young developing maize seeds at transcriptional levels. [ABSTRACT FROM AUTHOR]