The present manuscript highlights the potential role of Streptomyces roseoverticillatus 63 (Sr-63) against Xanthomonas oryzae pv. oryzae (Xoo), which is the cause of a disastrous bacterial leaf blight disease with rice worldwide. The disease suppression was achieved under greenhouse conditions. A foliar spray of the fermentation broth of Sr-63 significantly reduced the leaf blight symptoms with rice in Xoo inoculated rice plants. Furthermore, we observed that the carbazomycin B, isolated from the fermentation broth of Sr-63, was demonstrated to have antibacterial activity against Xoo with a minimum inhibitory concentration (MIC) of 8 μg mL^–1. The results indicated that carbzomycin B hampered the membrane formation of Xoo, reduced the production of xanthomonadin and extracellular polymeric substance (EPS). The fourier transform infrared spectroscopic (FT-IR) indicated that carbazomycin B changed the components of the cell membrane, then caused a change of the cell surface hydrophobicity of Xoo. Scanning electron microscopy revealed that the Xoo cells treated with carbazomycin B exhibited apparent structural deformation. The results also indicated that carbazomycin B had a negative impact on the metabolism of Xoo, carbazomycin B reduced the activity of malate dehydrogenase (MDH) activity and suppressed the protein expression of Xoo. Overall, our data suggests that Streptomyces roseoverticillatus 63 is a promising biocontrol agent that could be used to combat the bacterial leaf blight diseases of rice.

To screen for Aspergillus activity against Xanthomonas oryzae pv. oryzae and analyse the antimicrobial components involved, 60 Aspergillus spp. were isolated and purified from fruits, soil and other habitats. As-75, an Aspergillus strain that can antagonize Xanthomonas oryzae pv. oryzae, was identified based on the zone of inhibition formed during co-culture. According to morphological, ITS rDNA gene sequencing and phylogenetic tree results, the strain showed close homology to Aspergillus sclerotiorum. The biochemical characterization tests showed that the fermentation broth of strain As-75 exhibited a high capacity for environmental adaptation. The results of the antimicrobial spectrum experiments demonstrated that As-75 exhibited fairly strong antagonistic activity against five plant pathogenic fungi and six plant pathogenic bacteria in vitro. The fermentation broth of strain As-75 displayed maximum stability under fluorescent illumination at temperatures below 60°C at pH 6.5. A substance with antagonistic activity was obtained from strain As-75 via fractional extraction, silica gel column chromatography and thin-layer chromatography. Through mass spectrometry, nuclear magnetic resonance and electrospray ionization mass spectrometry (ESI-MS) analyses, the target compound was identified as (2Z)-2-butenedioic acid-2-(1-methylethenyl)-4-methyl ester; its molecular weight of 170.06 daltons and formula of C₈H₁₀O₄ identify it as a novel compound. Trials of the preventative and curative effects demonstrated that compound S1 exhibited a better control efficiency than the control against rice bacterial blight. Additionally, the M1 processing method was better, and the efficiency of compound S1 in preventing rice bacterial blight in six rice varieties, TN1, IR24, ZF802, Zhonghua 11, Wuyunjing 21, and Nipponbare, was 78.3%, 77.5%, 74.2%, 75.3%, 70.9%, and 72.1%, respectively.

The genus Gymnopus plays a significant role in ecological systems, with certain species holding potential as food or medicinal resources. However, the species diversity of Gymnopus in China remains unclear. In recent years, more than one thousand Gymnopus specimens have been collected across China. Thus, through the integration of ecological evidence, detailed morphological studies, and phylogenetic analysis using a multiloci dataset of ITS + nLSU + tef1-ɑ, four new species—Gymnopus longistipes, Gymnopus striatipileatus, Gymnopus viridiscus, and Gymnopus spadiceus—have been differentiated from known species. Gymnopus similis has been newly documented from Jiangxi Province, China. Detailed descriptions and vivid illustrations have been provided based on the newly collected specimens, along with comparisons to closely related species. Additionally, a key to the reported species of Gymnopus s.l. from East China has been included.

The genus Gymnopus has a long research history and is known for its high species diversity worldwide. However, its species diversity in China remains poorly understood. Through a combination of detailed morphological studies and phylogenetic analysis, this study described two new species from Northeast and Central China, Gymnopus biyangensis and Gymnopus sinodryophilus, both belonging to Gymnopus sect. Levipedes. Gymnopus biyangensis is characterized by basidiomata appearing in summer and originating from broad-leaved forests, a dark reddish-brown pileus, a cylindrical to clavate stipe, and clavate to cylindrical, diverticulate cheilocystidia. Gymnopus sinodryophilus differs by the yellowish-white to light brown basidiomata arising from coniferous and broad-leaved mixed forests, coralloid but inflated pileipellis terminal cells, and an apex of cheilocystidia not coralloid. Additionally, a key to the reported species of Gymnopus sect. Levipedes in China is provided.