The Slt2-type MAP kinase Bmp3 of Botrytis cinerea is required for normal saprotrophic growth, conidiation, plant surface sensing and host tissue colonization

Mitogen-activated protein kinases (MAPKs) play important roles in signal transduction and regulation of various aspects of saprotrophic and pathogenic growth in plant pathogenic fungi. We have generated a Botrytis cinerea knock-out mutant in the bmp3 gene encoding a homologue of the yeast Slt2 cell wall integrity MAPK. The Δ bmp3 mutant showed reduced vegetative growth on various media, strongly impaired conidiation and loss of sclerotia formation. Growth retardation of the mutant was enhanced in media with low osmolarity, whereas nearly wild-type growth rates were observed under high osmolarity conditions. The Δ bmp3 mutant did not show increased susceptibility to cell wall damage induced by glucanase, Calcofluor White or Nikkomycin Z, but was more susceptible to the oxidizing agent paraquat and the phenylpyrrole fungicide fludioxonil. Δ bmp3 conidia showed normal germination and germ tube growth on agar, but excessive germ tube elongation on hard surfaces and reduced penetration efficiency, indicating a defect in surface sensing. After penetration, development of necrotic lesions induced by the Δ bmp3 mutant was retarded. All these defects were restored by genetic complementation of the mutant with the wild-type bmp3 gene.     

Anatomy of an adaptive radiation: a unique reproductive strategy in the endemic freshwater gastropod Tylomelania (Cerithioidea: Pachychilidae) on Sulawesi, Indonesia and its biogeographical implications

The patterns of adaptive radiations in ancient lakes provide valuable clues to mechanisms of speciation and adaptation. In contrast to vertebrate radiations, for instance in fishes or finches, invertebrate species flocks have been largely neglected. While the increase in molecular data narrows this gap, the anatomical basis for interpreting these data against the background of evolutionary hypotheses is still widely lacking. Here we evaluate anatomical findings in the live‐bearing pachychilid freshwater gastropod Tylomelania, which has radiated extensively in ancient lakes in the Indonesian island, Sulawesi; we have aimed at reconciling these data with recently obtained molecular phylogenetic evidence. Discovered more than a century ago, the speciose and phenotypically diverse species flock with 34 currently described taxa was only occasionally cited as an example of adaptive radiation in ancient lakes, while anatomical data were entirely lacking. Our study of anatomical characters reveals very low qualitative variation at the species level. Thus, contrary to earlier views we suggest the existence of a single monophyletic lineage endemic to this island. The most conspicuous feature of Tylomelania is its uterine brooding strategy, i.e. retaining eggs and embryos in the pallial oviduct. This is unique among South‐East Asian pachychilids. Within the uterine brood pouch the offspring is surrounded by considerable amounts of nutritive material produced by a very large albumin gland, and the embryos are produced continuously. The shelled juveniles of some species are the largest known so far in viviparous gastropods, measuring almost 2 cm in length when hatching. This combination of reproductive features in Tylomelania, characterized by a high amount of maternal investment, is considered to be ovoviviparous, rendering its brooding strategy unique also among other gastropods. In addition, our data reject a previously assumed close relationship to other South‐East Asian pachychilids and instead suggest the North Australian Pseudopotamis as sister group to Tylomelania. These findings have significant consequences for the phylogenetic interpretation of morphological characters of Tylomelania in an evolutionary and biogeographical context, leading to the hypothesis that the common ancestor of both genera originated somewhere on the northern Australian continental margin. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85 , 513–542.     

Uncovering an overlooked radiation: molecular phylogeny and biogeography of Madagascar's endemic river snails (Caenogastropoda: Pachychilidae: Madagasikara gen. nov.)

By analysing key morphological characters (with emphasis on shell, radula and stomach anatomy) and a partial fragment of the mitochondrial 16S rRNA gene (alignment length 860 bp), we examined patterns of diversity and differentiation of a previously overlooked radiation of Madagascan pachychilid freshwater gastropods. These analyses resulted in the discovery of three new species in addition to the two species that were already recognized. The complex nomenclatural and taxonomic implications are discussed and the finding of a viviparous reproductive mode in at least one among otherwise oviparous species is reported. Using a mitochondrial phylogeny that includes all currently accepted pachychilid genera and a strict molecular clock approach, we address the historical biogeography of the Madagascan species with respect to vicariant versus dispersalist biogeographical models. Using two alternative calibrations that were previously suggested for other gastropods, the molecular clock tree suggested that the origin of the Pachychilidae dates back to no more than 50 Mya, whereas the origin of the Madagascan lineage is estimated to date to a period between 15.6–31.5 Mya. These estimates are approximately concurrent with the dating of colonization events in a number of other Madagascan animal taxa. The pachychilid radiation on Madagascar appears not to be older than 3–5 Mya. Thus, although the global patterns of pachychilid distribution have earlier been interpreted to suggest a Gondwanan origin of the family, the present study does not support this postulate. Neither the topology of the molecular phylogeny, nor the timing of events as suggested from a molecular clock were found to be congruent with a vicariance scenario within the framework of Gondwanan fragmentation during the Mesozoic but, instead, imply overseas dispersal during the Cenozoic. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 867–894.