Program Book - 27th Fungal Genetics Conference

CONCURRENT SESSION ABSTRACTSSaturday, March 16 2:00 PM–5:00 PMFred Farr ForumFungal Evo-DevoCo-chairs: Steve Harris and Brian ShawThe Molecular Foundations of the Fungal Lifestyle. Antonis Rokas. Department of Biological Sciences, Vanderbilt University, Nashville, TN.A defining characteristic of Fungi is that, in contrast to plants and animals, they are typically embedded in their food and digest it externally in thepresence of competitors (think of the blue lines of mold in blue cheese). Thus, different fungi specialize in “eating” different foods (hence their diverseprimary metabolism), and because digestion happens externally, fungi have also evolved potent food defense mechanisms (hence their diverse secondaryor specialized metabolism). In many ways, the genes involved in fungal primary metabolism are their “teeth”, whereas the genes involved in secondarymetabolism are their “horns”, “spines” and “claws”. I will use examples from our recent studies on fungal human pathogens, domesticated fungi andfungal genome evolution to argue that metabolism and more generally physiology is fundamental to the fungal lifestyle. In contrast to plants and animals,in which most phenotypic evolution proceeds largely through developmental changes affecting growth and morphological form, phenotypic evolution inthe fungal kingdom occurs largely through changes in metabolism.Gene expression and regulation during conidial morphogenesis in Neurospora crassa. Daniel J. Ebbole, Shengli Ding, Dawoon Chung, HeatherWilkinson, Shaw Brian. Plant Pathology & Microbiol, Texas A&M Univ, College Station, TX.The regulatory pathway controlling conidiation in N. crassa consists of five genes, acon-4 (aconidiate), fl (fluffy), acon-3, csp-1 (conidial separation) andcsp-2. The first three genes are required for the transition of aerial hyphae from filamentous growth to the budding pattern resulting in proconidial chainformation. Maturation of the proconidial chain to individual conidia relies on the activation of genes for two additional transcription factors, csp-1 and csp-2 that are required for proper interconidial septum formation and spore release. High throughput mRNA sequencing defined a set of genes induced duringconidiation and allowed us to identify genes for cell wall degrading enzymes required for conidial separation. Based on expression patterns and epistasisamong the regulators, we defined the order of gene action required for conidial morphogenesis from the initiation of budding to the release of matureconidia.Comparative developmental morphology in lentinoid mushrooms: toward a new fungal evo-devo? David S. Hibbett. Biology, Clark University, Worcester,MA.Fungi produce a mind-boggling diversity of complex forms, including mushrooms, puffballs, coral fungi, and others. Reconstructing patterns ofmorphological transformations has been a major focus of fungal molecular systematics, and developmental morphology has been a traditional source ofcharacters for fungal taxonomy. However, few studies have explicitly compared developmental programs in a phylogenetic context, and research into thegenetic bases of morphological evolution in fungi has lagged far behind that in plants and animals. In this talk, I will review three cases of naturallyoccurring developmental variation in the polyphyletic “lentinoid” fungi, which may suggest profitable avenues for studies in fungal evo-devo: 1) Normallyagaricoid species of Lentinus, Neolentinus and Lentinellus may be induced to produce coralloid forms under conditions of light deprivation or lowtemperatures. These phenomena provide examples of phenotypic plasticity that may reflect evolvability of developmental programs. 2) Panus rudis has ashort lateral stipe and fruits directly on wood, while the closely related P. fulvus has a dramatically elongated stipe and often fruits from sclerotiaimmersed in leaf litter. The developmental transformation between forms suggests a case of hypermorphosis, with a delayed onset of pileus initiation in P.fulvus. Light-induced formation of pilei in P. rudis may provide clues to the mechanisms of offset in stipe elongation. 3) Lentinus tigrinus is a gilledmushroom that has a naturally occurring “secotoid” mutant that has an enclosed, puffball-like hymenophore. The secotioid morphology appears to beconferred by a recessive allele at a single locus. Resolving the gene(s) responsible for the secotioid phenotype may provide clues to the evolution ofgasteromycetes. Complete genome sequences have been (or are being) produced for species of Lentinus, Panus, Lentinellus and Neolentinus, which willprovide opportunities to study the mechanisms underlying inter- and intraspecific developmental variants in lentinoid mushrooms.The Cdc42 GTPase module and the evolution of conidiophore architecture in Aspergillus. Steven D. Harris. Center Plant Sci Innovation, Univ Nebraska,Lincoln, NE.Conidiophores are reproductive structures that enable filamentous fungi to produce and disseminate large numbers of asexual spores. The diversity inconidiophore morphology is sufficiently large to serve as a basis for fungal systematics. Aspergillus and Penicillium species are members of the familyTrichocomaceae that form conidiophores with characteristic architecture. Whereas the Penicillium conidiophore appears to be a modified branchedhyphal structure, the Aspergillus conidiophore is seemingly more complex and includes additional cell types. Here, it is proposed that the “aspergillioid”conidiophore may have evolved from a “penicillioid” ancestor via changes in expression of key regulators of the GTPases Cdc42 and RacA. In particular,mutations that affect these regulators in A. nidulans dramatically alter conidiophore morphology by eliminating terminal vesicles and permitting formationof branched stalks. Because the transcriptional regulatory network that controls conidiophore development in Aspergillus is well characterized, furtherstudy of how this network links to regulators of Cdc42 should provide fundamental insight into the evolution of developmental morphogenesis in fungi(i.e., fungal evo-devo).Cdc14 association with basal bodies in the oomycete Phytophthora infestans indicates potential new role for this protein phosphatase. Audrey M.V. Ah-Fong, Howard S. Judelson. Plant Pathology & Microbiology, University of California, Riverside, CA.The dual-specificity phosphatase Cdc14 is best known as a regulator of cell cycle events such as mitosis and cytokinesis in yeast and animal cells.However, the diversity of processes affected by Cdc14 in different eukaryotes raises the question of whether its cell cycle functions are truly conservedbetween species. Analyzing Cdc14 in Phytophthora infestans should provide further insight into the role of Cdc14 since this organism does not exhibit aclassical cell cycle. Prior study in this organism already revealed novel features of its Cdc14. For example, instead of being post-translationally regulatedlike its fungal and metazoan relatives, PiCdc14 appears to be mainly under transcriptional control. It is absent in vegetative hyphae where mitosis occurs27th Fungal Genetics Conference | 93