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Cryptic species are common in Diplodia , a genus that includes some well-known and economically important plant pathogens. Thus, species delimitation has been based on the phylogenetic species recognition approach using multigene genealogies. We assessed the potential of mating type ( MAT ) genes sequences as phylogenetic markers for species delimitation in the genus Diplodia . A PCR-based mating type diagnostic assay was developed that allowed amplification and sequencing of the MAT1-1-1 and MAT1-2-1 genes, and determination of the mating strategies used by different species. All species tested were shown to be heterothallic. Phylogenetic analyses were performed on both MAT genes and also, for comparative purposes, on concatenated sequences of the ribosomal internal transcribed spacer (ITS), translation elongation factor 1-alpha ( tef1-α ) and beta-tubulin ( tub2 ). Individual phylogenies based on MAT genes clearly differentiated all species analysed and agree with the results obtained with the commonly used multilocus phylogenetic analysis approach. However, MAT genes genealogies were superior to multigene genealogies in resolving closely related cryptic species. The phylogenetic informativeness of each locus was evaluated revealing that MAT genes were the most informative loci followed by tef1-α . Hence, MAT genes can be successfully used to establish species boundaries in the genus Diplodia . [ABSTRACT FROM AUTHOR]

Recently oxysporone, a phytotoxic dihydrofuropyranone, was isolated along with two closely related compounds, afritoxinones A and B, from liquid cultures of Diplodia africana , an invasive fungal pathogen of Phoenicean juniper. In this study, eight derivatives were hemisynthesized and assayed for their phytotoxic and antifungal activities in comparison to the parent compound. Each compound was tested on non-host plants and on four destructive plant pathogens such as Athelia rolfsii , Diplodia corticola , Phytophthora cinnamomi and P. plurivora. The results on the phytotoxic activity showed that the dihydrofuropyranone carbon skeleton and both the double bond the hydroxy group of dihydropyran ring appeared to be structural features important in conferring activity. Although the data concerning the antifungal activity did not allow to extract any structure–activity relationships, it should be underlined that the conversion of oxysporone into the corresponding 4- O -benzoyl derivative led to a compound showing a good antifungal activity towards three out of the four organisms tested. [ABSTRACT FROM AUTHOR]

Abstract: Two phytotoxic dihydrofuropyran-2-ones, named afritoxinones A and B, were isolated from liquid culture of Diplodia africana, a fungal pathogen responsible for branch dieback of Phoenicean juniper in Italy. Additionally, six others known metabolites were isolated and characterized: oxysporone, sphaeropsidin A, epi-sphaeropsidone, R-(−)-mellein, (3R,4R)-4-hydroxymellein and (3R,4S)-4-hydroxymellein. The structures of afritoxinones A and B were established by spectroscopic and optical methods and determined to be as (3aS ∗,6R ∗,7aS)-6-methoxy-3a,7a-dihydro-3H,6H-furo[2,3-b]pyran-2-one and (3aR ∗,6R ∗,7aS)-6-methoxy-3a,7a-dihydro-3H,6H-furo[2,3-b]pyran-2-one, respectively. The phytotoxic activity of afritoxinones A and B and oxysporone was evaluated on host (Phoenicean juniper) and non-host plant (holm oak, cork oak and tomato) by cutting and leaf puncture assay. Oxysporone proved to be the most phytotoxic compound. This study represents the first report of secondary metabolites produced by D. africana. In addition, the taxonomic implications of secondary metabolites in Botryosphaeriaceae family studies are discussed. [Copyright &y& Elsevier]

Highlights: [•] Three jasmonic acid esters were isolated from a Lasiodiplodia sp. phylogenetically closely related to Lasiodiplodia. [•] A trisubstituted- and two tetrasubstituted-dihydrofuranones were characterized. [•] Lasiodiplodia sp. is an aggressive pathogen on grapevine. [•] The main phytotoxin is the jasmonic acid, while its ester could be a reverve of toxin. [Copyright &y& Elsevier]