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Lucas-Gallegos, Brenda Lizeth [1], Villegas-Rios, Margarita [1], Garibay-Orijel, Roberto [2], Perez-Pazos, Eduardo [3].

Host specificity of the mycoparasite Helminthosphaeria clavariarum associated with Clavulina sp.

The symbiosis in which one fungus gets nutrients from another fungus is referred to as mycoparasitism.  Helminthosphaeria clavariarum  (Sordariales, Ascomycota) establish a mycoparasitic interaction with  Clavulina  sporocarps (Cantharellales, Basidiomycota). Nevertheless, the degree of host specificity, as well as the nutrition mode of  H. clavariarum, remains almost unexplored. Here, the symbionts' identity by means of morphological, molecular, and ecological methods was analyzed. Furthermore, the incidence and severity of the mycoparasitic interaction as well as the degree of host specificity on  Clavulina  spp. sporocarps were studied. Mushroom harvests were held during the rainy season of 2018 at two temperate forest sites in Puebla, Mexico.  Clavulina  (host) sporocarps with signs mycoparasitism (dark pigmentation and rough surfaces at the base of the sporocarp) were harvested. Macro- and micromorphological features from both symbionts were described and used to delimit morph species. Fresh fragments from host infected sporocarps were surface sterilized and inoculated on different media to obtain a strain of the mycoparasite. DNA was extracted from at least one specimen per morph species. The ITS region was amplified for  Clavulina. LSU primers were designed for the identification of the mycoparasite, and the amplification was made using the same DNA as for the host. All sequences were compared against the NCBI database and phylogenetic analyses (Bayesian Inference and Maximum Likelihood) were performed. The incidence and severity were calculated for each  Clavulina  species. Mycoparasite morphological variation when interacting with different hosts was assessed using Principal Component Analyses and a Kruskal-Wallis test. Five  Clavulina  species with signs of mycoparasitism were identified. One of those is proposed as a new species for the genus, belonging to the  Clavulina rugosa  complex. Morphological characters described from infected sporocarps, mainly in the asexual stage, allowed us to identify the mycoparasite as  Helminthosphaeria clavariarum. However, we were unable to amplify the LSU region of the mycoparasite and no strain was recovered from cultures. The most conspicuous morphological alterations on the hosts were the branching pattern and branch shapes.  H. clavariarum  incidence ranged from 25-49 % and some  Clavulinaspecies showed higher severity values than others. The sexual stage was almost absent at the sampling sites. The morphology of  H. clavariarum  varied between host species, suggesting a potential differentiation of two variants of the mycoparasite. These results integrate new data regarding the interaction between  H. clavariarum  and  Clavulina  spp., opening the door for future projects involving host-specificity in mycoparasitic interactions.

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1 - Facultad de Ciencias, Universidad Nacional Autónoma de México, Biología Comparada, Circuito Exterior s/n, Ciudad Universitaria, Coyoacán, Mexico City, 04510, México
2 - Instituto de Biología, Universidad Nacional Autónoma de México,, Botánica, Tercer Circuito s/n, Ciudad Universitaria, Coyoacán, Mexico City, 04510, México
3 - University of Minnesota, Ecology Evolution and Behavior, 1479 Gortner Ave, Saint Paul, MN, 55108, USA

Integrative taxonomy

Presentation Type: Poster
Session: MYP2, Mycology Posters II
Location: Virtual/Virtual
Date: Tuesday, July 20th, 2021
Time: 5:00 PM(EDT)
Number: MYP2017
Abstract ID:961
Candidate for Awards:MSA Best Poster Presentation Award by an Undergraduate Student

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