A new species of Panaeolus (Agaricales, Basidiomycota) from Yunnan, Southwest China

A new Panaeolus species was collected on a lawn at the Kunming Institute of Botany, Chinese Academy of Sciences in Southwest China and subjected to morphological and molecular analyses. Both macro- and micro-morphological features of the new species were described and compared with morphologically similar species in Panaeolus. The pileus has a distinctive reddish brown patch at the center. Phylogenetic analysis of nrITS data showed a distinct placement of the new species among the closest Panaeolus species, i.e. Panaeolus cyanescens (Berk & Broome) Sacc., Panaeolus cambodginiensis Ola’h & R. Heim, Panaeolus bisporus (Malençon & Bertault) Ew. Gerhardt and Panaeolus cyanescens var. bisporus (Malençon & Bertault) G. Moreno & Esteve-Rav. Both morphological features and phylogenetic data supported naming our taxon as a distinct new species in Panaeolus. Color photographs of basidiomata and micromorphological structures, a full description of the new species, and an updated phylogenetic tree to show the placement of the new species are provided.

Screening Tall Fescue for Resistance to Rhizoctonia solani and Rhizoctonia zeae Using Digital Image Analysis

Brown patch, caused by Rhizoctonia solani, is a destructive disease on tall fescue. Compared with R. solani, Rhizoctonia zeae causes indistinguishable symptoms in the field but varies in geographic distribution. This may contribute to geographic variability observed in the resistance response of improved brown patch–resistant cultivars. This study examined R. solani and R. zeae susceptibility of four cultivars, selected based on brown patch performance in the National Turfgrass Evaluation Program (NTEP), and nine plant introductions (PIs). Twenty genotypes per PI/cultivar were evaluated by using four clonal replicates in a randomized complete block design. Plants were inoculated under controlled conditions with two repetitions per pathogen. Disease severity was assessed digitally in APS Assess, and analysis of variance and correlations were performed in SAS 9.3. Mean disease severity was higher for R. solani (65%) than for R. zeae (49%) (P = 0.0137). Interaction effects with pathogen were not significant for PI (P = 0.0562) but were for genotype (P < 0.001). Moderately to highly resistant NTEP cultivars compared with remaining PIs exhibited lower susceptibility to R. zeae (P < 0.0001) but did not differ in susceptibility to R. solani (P = 0.7458). Correlations between R. solani and R. zeae disease severity were not significant for either PI (R = 0.06, P = 0.8436) or genotype (R = 0.11, P = 0.09). Breeding for resistance to both pathogens could contribute to a more geographically stable resistance response. Genotypes were identified with improved resistance to R. solani (40), R. zeae (122), and both pathogens (26).

Brachypodium: A Potential Model Host for Fungal Pathogens of Turfgrasses

Brachypodium distachyon is a C3 grass that is an attractive model host system for studying pathogenicity of major turfgrass pathogens due to its genetic similarity to many cool-season turfgrasses. Infection assays with two or more isolates of the casual agents of dollar spot, brown patch, and Microdochium patch resulted in compatible interactions with B. distachyon inbred line Bd21-3. The symptoms produced by these pathogens on Bd21-3 closely resembled those observed on the natural turfgrass host (creeping bentgrass), demonstrating that B. distachyon is susceptible to the fungal pathogens that cause dollar spot, brown patch, and Microdochium patch on turfgrasses. The interaction between Sclerotinia homoeocarpa isolates and Brachypodium ecotypes was also investigated. Interestingly, differential responses of these ecotypes to S. homoeocarpa isolates was found, particularly when comparing B. distachyon to B. hybridum ecotypes. Taken together, these findings demonstrate that B. distachyon can be used as a model host system for these turfgrass diseases and leveraged for studies of molecular mechanisms contributing to host resistance.