The velvet family proteins have been shown to play critical roles in fungal secondary metabolism and development. However, variations of the roles have been observed in different fungi. We report here the observation on the role of three velvet complex components VeA, VelB, and LaeA in Pestalotiopsis microspora, a formerly reported taxol-producing fungus. Deletion of individual members led to the retardation of vegetative growth and sporulation and pigmentation, suggesting critical roles in these processes. The mutant strain △velB appeared hypersensitive to osmotic stress and the dye Congo red, whereas △veA and △laeA were little affected by the pressures, suggesting only velB was required for the integrity of the cell wall. Importantly, we found that the genes played distinct roles in the biosynthesis of secondary metabolites in P. microspora. For instance, the production of pestalotiollide B, a previously characterized polyketide, required velB and laeA. In contrast, the veA gene appeared to inhibit the pestalotiollide B (PB) role in its biosynthesis. This study suggests that the three components of the velvet complex are important global regulators, but with distinct roles in hyphal growth, asexual production, and secondary metabolism in P. microspora. This work provides information for further understanding the biosynthesis of secondary metabolism in the fungus.

Highly conserved, the Snf1/AMPK is a central regulator of carbon metabolism and energy production in the eukaryotes. However, its function in filamentous fungi has not been well established. In this study, we reported functional characterization of Snf1/AMPK in the growth, development and secondary metabolism in the filamentous fungus Pestalotiopsis microspora. By deletion of the yeast SNF1 homolog, we found that it regulated the utilization of carbon sources, e.g., sucrose, demonstrating a conserved function of this kinase in filamentous fungus. Importantly, several novel functions of SNF1 were unraveled. For instance, the deletion strain displayed remarkable retardation in vegetative growth and pigmentation and produced a diminished number of conidia, even in the presence of the primary carbon source glucose. Deletion of the gene caused damages in the cell wall as shown by its hypersensitivities to Calcofluor white and Congo red, suggesting a critical role of Snf1 in maintaining cell wall integrity. Furthermore, the mutant strain Δsnf1 was hypersensitive to stress, e.g., osmotic pressure (1 M sorbitol), drug G418 and heat shock, though the mechanism remains to be illustrated. Significantly, disruption of the gene altered the production of secondary metabolites. By high-performance liquid chromatography (HPLC) profiling, we found that Δsnf1 barely produced secondary metabolites, e.g., the known product pestalotiollide B. This study suggests that Snf1 is a key regulator in filamentous fungus Pestalotiopsis microspora concerting carbon metabolism and the filamentous growth, conidiation, cell wall integrity, stress tolerance and the biosynthesis of secondary metabolites.

Phoma macdonaldii (teleomorph Leptosphaeria lindquistii) is the causal agent of sunflower (Helianthus annuus L.) black stem. In order to investigate the molecular basis for the pathogenicity of P. ormacdonaldii, genomic and transcriptomic analyses were performed. The genome size was 38.24 Mb and assembled into 27 contigs with 11,094 putative predicted genes. These include 1133 genes for CAZymes specific for plant polysaccharide degradation, 2356 for the interaction between the pathogen and host, 2167 for virulence factors, and 37 secondary metabolites gene clusters. RNA-seq analysis was conducted at the early and late stages of the fungal spot formation in infected sunflower tissues. A total of 2506, 3035, and 2660 differentially expressed genes (DEGs) between CT and each treatment group (LEAF-2d, LEAF-6d, and STEM) were retrieved, respectively. The most significant pathways of DEGs from these diseased sunflower tissues were the metabolic pathways and biosynthesis of secondary metabolites. Overall, 371 up-regulated DEGs were shared among LEAF-2d, LEAF-6d, and STEM, including 82 mapped to DFVF, 63 mapped to PHI-base, 69 annotated as CAZymes, 33 annotated as transporters, 91 annotated as secretory proteins, and a carbon skeleton biosynthetic gene. The most important DEGs were further confirmed by RT-qPCR. This is the first report on the genome-scale assembly and annotation for P. macdonaldii. Our data provide a framework for further revealing the underlying mechanism of the pathogenesis of P. macdonaldii, and also suggest the potential targets for the diseases caused by this fungal pathogen.

Five medicinal plants with various therapeutic effects in Xinjiang ( Helichrysum thianschanicum Regel, Taraxacum kok-saghyz Rodin , Artemisia rupestris L. , Arnebia euchroma Johnst, and Hyssopus officinalis L.) are considered as promising raw materials of pharmaceutical, cosmetic, and fragrance industries. Understanding the characteristics of rhizosphere bacterial communities can be critical in regulating the growth process of these medicinal plants. To clarify the plant-specificity of rhizobacterial assemblages and related driving factors of five medicinal plants, we compared their rhizosphere bacterial communities with those of non-planted soil (CK). Soil physicochemical properties were analyzed, and bacterial communities were characterized using high-throughput sequencing of the 16S rRNA gene V3–V4 region. Results showed that rhizosphere soils of medicinal plants had significantly higher organic matter (OM), total nitrogen (TN), and total phosphorus (TP) than CK, with TP increasing by 2.6–2.9 times. Each medicinal plant rhizosphere harbored a highly specific bacterial community, with unique Amplicon Sequence Variants (ASVs) accounting for 34.04–46.70% of total ASVs, while only 449 core ASVs were shared among all five plants. At the phylum level, Proteobacteria , Bacteroidota , and Acidobacteriota dominated the rhizosphere, in contrast to the dominance of Actinobacteriota in CK. Chitinophagaceae , Sphingomonas , Pseudomonas and RB41 were selectively enriched in different plant rhizospheres. Total potassium (TK), TN, and TP were the key edaphic drivers, with TK negatively correlated with bacterial diversity, and TN/TP regulating the distribution of dominant genera. This study demonstrates high plant-specificity of rhizobacterial communities in Xinjiang medicinal plants and the dominant role of soil TK, TN, and TP, providing a scientific basis for the precise cultivation of medicinal plants and the development of specialized microbial agents.