Glycomyces niveus sp. nov., a novel actinomycete isolated from sandy soil.

A novel mycelium-forming actinomycete, designated strain NEAU-S30T, was isolated from the sandy soil of a sea beach in Shouguang city, Shandong province, PR China. The strain developed long chains of non-motile cylindrical spores with smooth surfaces on aerial mycelia. The results of a polyphasic taxonomic study indicated that NEAU-S30T represented a member of the genus Glycomyces. The results of 16S rRNA gene sequence analysis indicated that NEAU-S30T was closely related to 'Glycomycesluteolus' (98.97 % sequence similarity), Glycomycesalgeriensis (98.90 %), 'Glycomyces tritici' (98.83 %) and Glycomyces lechevalierae (98.76 %). The average nucleotide identity (ANI) values between NEAU-S30T and 'G. luteolus' NEAU-A15, G. algeriensis DSM 44727T, 'G. tritici' NEAU-C2 and G. lechevalierae DSM 44724T were 87.77, 87.53, 87.41 and 87.80 %, respectively. The digital DNA G+C content of the genomic DNA was 70.5 %. The whole-cell sugars contained ribose and xylose. The predominant menaquinones were MK-10(H2), MK-10(H4) and MK-10(H6). The predominant fatty acids were anteiso-C15 : 0, iso-C16 : 0, anteiso-C17 : 0 and iso-C15 : 0. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphoglycolipid, phosphatidylinositol, phosphatidylinositol mannoside and an unidentified glycolipid. On the basis of the results of comparative analysis of genotypic, phenotypic and chemotaxonomic data, the novel actinomycete strain NEAU-S30T (=JCM 33975T=CGMCC 4.7890T) represents the type strain of a novel species within the genus Glycomyces, for which the name Glycomyces niveus sp. nov. is proposed.

Alternaria spp. Associated with Leaf Blight of Maize in Heilongjiang Province, China.

Maize (Zea mays L.) is a major economic crop worldwide. Maize can be infected by Alternaria species causing leaf blight that can result in significant economic losses. In this study, 168 Alternaria isolates recovered from symptomatic maize leaves were identified based on morphological characteristics, pathogenicity, and multilocus sequence analyses of the genes glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the internal transcribed spacer of ribosomal DNA (rDNA ITS), the RNA polymerase II second largest subunit (RPB2), and histone3 (HIS3). Maize isolates grouped to four Alternaria species including Alternaria tenuissima, A. alternata, A. burnsii, and Alternaria sp. Notably, A. tenuissima (71.4%) was the most prevalent of the four isolated species, followed by A. alternata (21.5%), Alternaria sp. (4.1%), and A. burnsii (3.0%). Pathogenicity tests showed that all four Alternaria species could produce elliptic to nearly round, or strip, lesions on leaves of maize, gray-white to dry white in the lesion centers and reddish-brown at the edges. The average disease incidence (58.47%) and average disease index (63.55) of maize leaves inoculated with A. alternata were significantly higher than levels resulting from A. tenuissima (55.28% and 58.49), Alternaria sp. (55.34% and 58.75), and A. burnsii (56% and 55). Haplotype analyses indicated that there were 14 haplotypes of A. tenuissima and five haplotypes of A. alternata in Heilongjiang Province and suggested the occurrence of a population expansion. Results of the study showed that Alternaria species associated with maize leaf blight in Heilongjiang Province are more diverse than those that have been previously reported. This is the first report globally of A. tenuissima, A. burnsii, and an unclassified Alternaria species as causal agents of leaf blight on maize.

First Report of Leaf Blight Caused by Limonomyces roseipellis on Maize (Zea mays L) in China.

Maize (Zea mays L.) is one of the major crops in China. In July 2020, leaf blight was observed on approximately 18% of maize plants at the 852 Farm, Heilongjiang province. Symptoms appeared as yellow necrotic lesions on leaf tips and margins, which later expanded to the entire. The disease was first observed on the lower leaves of the plants and then progressed up the plant. Thirty symptomatic leaves were collected in 2020, and tissue samples between healthy and necrotic area (4 × 2 mm) were surface disinfected with 1% NaOCl for 3 min, 70% ethanol for 10 s, and washed three times with sterile water. Disinfected tissues were placed on potato dextrose agar (PDA) amended with streptomycin sulfate (50 mg/liter) and incubated at 25°C for 1 week. Cultures were purified using the hyphal-tip technique for morphological and molecular analyses. Morphological characteristics were observed on 1-week-old PDA cultures grown at 25°C. Mycelium changed from cream colored to pale pink or reddish, and the back of plate turned pink with time. Hyphae were hyaline, 2 to 7 µm wide, with clamps at primary septa. Hyaline basidiospores were sphere to ellipsoid, and ranged from 8 to 10 × 6 to 9 µm. Based on the presence of clamp connections and morphological features, the fungus was preliminarily identified as Limonomyces roseipellis (Stalpers et al. 1982). To confirm the identity of L. roseipellis, primers ITS1/ITS4 (White et al. 1990), MS1/MS2 (White et al. 1990), and LR0R/LR5 (Vilgalys and Hester 1990) were used to amplify the internal transcribed spacer (ITS) region, the partial mitochondrial small subunit rDNA (mtSSU) and nuclear large subunit rDNA (nuLSU), respectively. These sequences were deposited in GenBank (GenBank accession no.s MW067756, MW322806 and MW386178). The ITS sequence had 99.55% nucleotide identity (660 bp/668 bp) with L. roseipellis isolate EF82 (GenBank accession no. MK918632). The mtSSU sequence was 99.69% identical (634 bp/636 bp) to that of L. roseipellis strain SY-LQG101 (Genbank accession no. KF824718). The nuLSU sequence was 99.14% identical (924 bp/932 bp) to that of L. roseipellis (GenBank accession no. EU622844). A single basidiospore was isolated and cultured on PDA for pathogenicity testing. To fulfill Koch's postulates, ten healthy, surface-disinfected maize plants grown in pots (four to five leaves stage) were sprayed with basidiospore suspension (1×106 spores/ml); another ten healthy surface-disinfected maize plants sprayed with distilled water to serve as controls. Plants were sealed in plastic bags immediately after inoculation and maintained at 90% relative humidity in a mist chamber for 24 h at 25°C with a 12-h light cycle (Nicoli et al. 2016). Plants were moved and maintained in the greenhouse and observed for disease development. The experiment was conducted twice. Leaf blight symptoms appeared on all inoculated plants 3 to 5 days postinoculation and were consistent with symptoms observed in the field. No disease symptoms were observed on control plants. The pathogen was reisolated from diseased plants, and species identification was confirmed by the morphological and molecular method described. L. roseipellis has been reported to infect Cynodon dactylon, Lolium perenne and Festuca arundinacea, respectively. To our knowledge, this is the first report of the identification of L. roseipellis as a pathogen of maize in China, and this report will assist with monitoring distribution of the disease to assist with developing management recommendations.