Identification of Cyprodinil + Fludioxonil to Manage Soybean Red Crown Rot Using the Microplate-Based High-Throughput Screening and Pot Assay.

Red crown rot (RCR), caused by the soilborne fungus Calonectria ilicicola, is an emerging soybean disease in Taiwan, and fungicide screening is desired to identify effective management for C. ilicicola. This study screened 11 fungicides, including azoxystrobin, boscalid, cyprodinil, cyprodinil + fludioxonil, difenoconazole, fluopyram, flutolanil, mancozeb, prochloraz, pyraclostrobin, and tebuconazole, for their inhibitory effects on the mycelial growth of 10 C. ilicicola field isolates. Subsequently, a microplate-based high-throughput screening (MHTS) method was established to measure the fungicide sensitivity in a population composed of 80 C. ilicicola isolates to three effective fungicides, cyprodinil + fludioxonil, fluopyram, and tebuconazole. The MHTS was optimized for multiple factors, including the optical scanning pattern, absorption wavelength, conidial concentration, and measurement timing based on the quality controls of Z' factor and the log-phase growth curve. The population mean EC50 estimated by MHTS were 0.14, 2.34, and 2.46 ppm to cyprodinil + fludioxonil, fluopyram, and tebuconazole, respectively. In addition to the in vitro assessment, fungicide efficacy was evaluated by coating cyprodinil + fludioxonil, fluopyram, or tebuconazole on soybean seeds in the pot assay. The results showed that cyprodinil + fludioxonil significantly reduced both postemergence damping-off and disease severity, while fluopyram and tebuconazole reduced only the postemergence damping-off but not disease severity. Based on the MHTS and the pot assay results, this study demonstrated cyprodinil + fludioxonil to be a potential fungicide to manage soybean RCR.

Whole-Genome Sequence Resource of Calonectria ilicicola, the Casual Pathogen of Soybean Red Crown Rot.

Calonectria ilicicola (anamorph: Cylindrocladium parasiticum) is a soilborne plant-pathogenic fungus with a broad host range, and it can cause red crown rot of soybean and Cylindrocladium black rot of peanut, which has become an emerging threat to crop production worldwide. Limited molecular studies have focused on Calonectria ilicicola and one of the possible difficulties is the lack of genomic resources. This study presents the first high quality and near-completed genome of C. ilicicola, using the Oxford Nanopore GridION sequencing platform. A total of 16 contigs were assembled and the genome of C. ilicicola isolate F018 was estimated to have 11 chromosomes. Currently, the C. ilicicola F018 genome represents the most contiguous assembly, which has the lowest contig number and the highest contig N50 among all Calonectria genome resources. Putative protein-coding sequences and secretory proteins were estimated to be 17,308 and 1,930 in the C. ilicicola F018 genome, respectively; and the prediction was close to other plant-pathogenic fungi, such as Fusarium species, within the Nectriaceae family. The availability of this high-quality genome resource is expected to facilitate research on fungal biology and genetics of C. ilicicola and to support advanced understanding of pathogen virulence and disease management.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Three new species of Iodosphaeria (Xylariomycetidae): I.chiayiensis, I.jinghongensis and I.thailandica.

Three fungal specimens (two sexual and one asexual) were collected during fieldwork conducted in China, Taiwan and Thailand. Both sexual morphs share superficial, black ascomata surrounded by flexuous setae; 8-spored, unitunicate, cylindrical asci, with J+, apical ring, and ellipsoidal to allantoid, aseptate, guttulate ascospores. The asexual morph has ceratosporium-like conidia arising from aerial hyphae with a single arm and are usually attached or with 2-3 arms, brown, often with a subglobose to conical cell at the point of attachment. Morphological examinations and phylogenetic analyses of a combined LSU-ITS dataset via maximum likelihood and Bayesian analyses indicated that these three collections were new species. Iodosphaeriachiayiensis (sexual morph), I.thailandica (sexual morph) and I.jinghongensis (asexual morph) are therefore introduced as new species in this study. Iodosphaeriachiayiensis has small, hyaline and ellipsoidal to allantoid ascospores, while I.thailandica has large ascomata, cylindrical to allantoid asci and hyaline to pale brown ascospores.

Two new species and one new record of Xenosporium with ellipsoidal or ovoid conidia from Taiwan.

Three species of Xenosporium producing ellipsoidal or ovoid conidia were collected from decaying culms of Miscanthus floridulus submerged in freshwater streams of Alishan area, Chiayi County, Taiwan. Xenosporium formosiforme and X. parvulum are described and illustrated as new species. Xenosporium africanum is described in this paper as a new record for Taiwan. The phylogenetic relationships of Xenosporium species and related taxa were sought by comparing the sequences of their internal transcribed spacer (ITS) barcode, 28S rDNA, and RNA polymerase II second largest subunit (RPB2) gene segments. Phylogenetic analysis of these Xenosporium species supports their placement in the Tubeufiaceae. A synopsis of Xenosporium species producing ellipsoidal or ovoid conidia is given. The criteria used to differentiate species are discussed.

Additions to Phaeosphaeriaceae (Pleosporales): Elongaticollum gen. nov., Ophiosphaerella taiwanensis sp. nov., Phaeosphaeriopsis beaucarneae sp. nov. and a new host record of Neosetophoma poaceicola from Musaceae.

A novel ascomycetous genus, Elongaticollum, occurring on leaf litter of Hedychium coronarium (Zingiberaceae) in Taiwan, is described and illustrated. Elongaticollum is characterized by dark brown to black, superficial, obpyriform, pycnidial conidiomata with a distinct elongate neck, and oval to oblong, hyaline, aseptate conidia. Phylogenetic analyses (maximum likelihood, maximum parsimony and Bayesian) of combined ITS, LSU, SSU and tef1-α sequence data revealed Elongaticollum as a distinct genus within the family Phaeosphaeriaceae with high statistical support. In addition, Ophiosphaerella taiwanensis and Phaeosphaeriopsis beaucarneae are described as new species from dead leaves of Agave tequilana and Beaucarnea recurvata (Asparagaceae), respectively. Neosetophoma poaceicola is reported as a new host record from dead leaves of Musa acuminata (Musaceae). Newly described taxa are compared with other similar species and comprehensive descriptions and micrographs are provided.

Additions to Chaetothyriaceae (Chaetothyriales): Longihyalospora gen. nov. and Ceramothyrium longivolcaniforme, a new host record from decaying leaves of Ficus ampelas.

A novel ascomycete genus, Longihyalospora, occurring on leaf litter of Ficus ampelas in Dahu Forest Area in Chiayi, Taiwan is described and illustrated. Longihyalospora is characterized by dark mycelium covering the upper leaf surface, elongate mycelial pellicle with ring of setae, pale brown to brown peridium, broadly obovoid, short pedicellate asci and hyaline, fusiform, elongated (tapering ends) and multi-septate ascospores with a thin mucilaginous sheath. Phylogenetic analyses of combined ITS, LSU and SSU sequence data revealed Longihyalospora as a distinct genus within the Chaetothyriaceae with high bootstrap support. Moreover, based on morphological similarities, Chaetothyrium vermisporum transferred to the new genus. In addition, Ceramothyrium longivolcaniforme is reported for the first time on Ficus ampelas. Newly added species are compared with other similar species and comprehensive descriptions and micrographs are provided.

Investigation of microbial elicitation of trans-resveratrol and trans-piceatannol in peanut callus led to the application of chitin as a potential elicitor.

It is well-known that the invasion of microbes such as fungi in some plants, including peanut, can induce the biosynthesis of stilbenoids such as trans-resveratrol and trans-piceatannol. However, in a recent study it was found that not all kinds of microorganisms possessed such potential. The Gram-negative bacterium Pseudochrobactrum asaccharolyticum isolated from the peanut callus failed to act as an elicitor. After systematic investigation, the different inductive effects between fungi and Gram-negative bacteria were attributed to the chitin content of the cell wall. Results showed significantly more trans-resveratrol and trans-piceatannol was induced by fungi (8.92-16.35 and 2.15-7.01 microg/g of fresh calluses, respectively) than by bacteria (1.77-2.72 and 0.16-0.52 microg/g of fresh calluses, respectively), regardless of species and viability. Such great differences prompted the direct utilization of chitin, the distinctive component of fungal cell wall, as an elicitor. The results that trans-resveratrol induced by chitin was about two-thirds the amount induced by sterilized fungi, whereas trans-piceatannol (2.55+/-0.60 microg/g) was close to that by sterilized fungi, revealed chitin is not only an important fungal constituent responsible for the induction of trans-resveratrol and trans-piceatannol but also an efficient elicitor by itself. These findings suggested sterilized fungi and chitin can be used as a safe and fast elicitor, as far as the risk of viable microbes is concerned, to induce trans-resveratrol and trans-piceatannol in the well-controlled peanut tissue culture.

Medicinal mushroom Ganoderma lucidum as a potent elicitor in production of t-resveratrol and t-piceatannol in peanut calluses.

Phytoalexins t-resveratrol and t-piceatannol, the well-known health-promoting active components in plants, are secondary metabolites generated upon biotic or abiotic stresses. We have reported UV-irradiated peanut callus is a potent means to produce these compounds (J. Agric. Food Chem. 2005, 53, 3877). In this work, the effects of fungi and chemical elicitors on induction of t-resveratrol and t-piceatannol were examined. Results showed the investigated fungi Botryodiplodia theobromae and Reishi Ganoderma lucidum were generally more effective than chemical stress methyl jasmonate, salicylic acid, and sucrose. As high as 15.46+/-9.85 microg of t-resveratrol and 6.93+/-2.03 microg of t-piceatannol could be elicited in each gram of callus by sterilized G. lucidum mycelium (80 mg). Although much more sterilized G. ludicum mycelia was required to induce similar level of t-resveratrol and t-piceatannol in comparison to the sterilized B. theobromae mycelia (1 mg), uptake of the G. ludicum mycelium may provide a variety of health-promoting effects. Our findings suggest G. ludicum mycelium-treated peanut callus is a good source of bioactive components.