Blackleg is a worldwide disease of canola (Brassica napus), caused by a complex of fungal species in the genus Leptosphaeria, that impacts canola production and seed quality. Demethylation inhibitor (DMI) fungicides that target sterol 14α-demethylase are an integral part of disease control. Here, we report six DMI-resistant isolates of Leptosphaeria maculans and two different types of genetic modification related to the resistance. Analysis of the regulatory region of the DMI target gene ERG11 (also known as CYP51) revealed a 275-bp insertion in two of the isolates and three long terminal repeat retrotransposons (5,263, 5,267, and 5,248 bp) inserted in the promoter region of three resistant isolates. Genetic approaches confirmed that these elements are responsible for DMI resistance in L. maculans and crosses show segregation consistent with a single locus. Reverse-transcription quantitative PCR assays demonstrated that the 275-bp insertion increases ERG11 gene expression, conferring DMI fungicide resistance both in vitro and in planta. Moreover, transformation of a susceptible isolate of L. maculans with ERG11 driven by a promoter containing the 275-bp insertion increased resistance to tebuconazole. A minimal shift of the values of concentration whereby 50% of the mycelial growth is inhibited in vitro was observed in resistant isolates containing long terminal repeat retrotransposons; nevertheless, these isolates were able to develop significant lesions on cotyledons from fungicide-treated seedlings. This is the first report of genetic modifications in L. maculans relating to DMI fungicide resistance.

Fusarium crown and root rot (FCRR), caused by Fusarium oxysporum f. sp. radicis-lycopersici (FORL), is an economically important disease that affects tomatoes worldwide and has become more prevalent in China in recent years. In 2021 and 2022, tomato plants in greenhouses in Hohhot, Inner Mongolia, were observed showing symptoms of stunting, premature loss of lower leaves, and root rot. Fungal pathogens were isolated from 20 infected tomato plants and identified based on morphological observation and DNA sequencing. Twelve isolates were consistently identified as Fusarium oxysporum f. sp. radicis-lycopersici (FORL) via an analysis of the ITS, TEF-1α, and pgx4 genes. This is the first report of FORL in Inner Mongolia, China. The isolates were examined for their pathogenicity by inoculating them on tomatoes, eggplants, peppers, and chickpeas. The fungicide sensitivity of the isolates was determined. Effective concentrations for 50% growth inhibition (EC₅₀) were measured using seven fungicides. The EC₅₀ values of tebuconazole and prochloraz were <1.0 μg·mL⁻¹, exhibiting the most effective inhibition among the fungicides tested. Additionally, FORL resistance screening of tomato germplasms was performed. One tomato variety was resistant to FORL, and the remaining 43 germplasm lines showed various levels of resistance. The rates of highly susceptible, moderately susceptible, susceptible, and moderately resistant germplasms accounted for 29.55%, 22.73%, 40.91%, and 4.55% of the 44 germplasms tested, respectively.

The horizontal transfer of large gene clusters by mobile elements is a key driver of prokaryotic adaptation in response to environmental stresses. Eukaryotic microbes face similar environmental stresses yet a parallel role for mobile elements has not yet been established. A stress faced by all microorganisms is the prevalence of toxic metals in their environment. In fungi, identified mechanisms for protection against metals generally rely on genes that are dispersed within an organism’s genome. Here we have discovered a large (∼85 kb) region that confers resistance to several metals in the genomes of some, but not all, strains of a fungus, Paecilomyces variotii . We name this region HEPHAESTUS ( Hϕ ) and present evidence that this region is mobile within the P. variotii genome with features highly characteristic of a transposable element. While large gene clusters including those for the synthesis of secondary metabolites have been widely reported in fungi, these are not mobile within fungal genomes. HEPHAESTUS contains the greatest complement of host-beneficial genes carried by a transposable element in eukaryotes. This suggests that eukaryotic transposable elements might play a role analogous to their bacterial counterparts in the horizontal transfer of large regions of host-beneficial DNA. Genes within HEPHAESTUS responsible for individual metal resistances include those encoding a P-type ATPase transporter, PcaA, required for cadmium and lead resistance, a transporter, ZrcA, providing resistance to zinc, and a multicopper oxidase, McoA, conferring resistance to copper. Additionally, a subregion of Hϕ conferring resistance to arsenate was identified. The presence of a strikingly similar cluster in the genome of another fungus, Penicillium fuscoglaucum , suggests that HEPHAESTUS arrived in P. variotii via horizontal gene transfer.

Fruit rot is one of the major diseases impacting the production and quality of zucchini (Cucurbita pepo). In August 2021, fruit rot symptoms were observed on the zucchini fruit ‘Jindi 1’ in the Wuyuan region in Inner Mongolia, China with an incidence ranging from 10% to 30%. Where the pepo was in contact with the soil, dark grey and spongy corky lesions 4–5 cm in diameter with a light brown halo were observed. The internal necrosis of the fruit rind was also recorded. From the affected fruits, fungal colonies belonging to the Fusarium species were exclusively isolated. Molecular analysis of the ITS, TEF-1α, and RPB2 sequences identified the isolates as Fusarium solani f. sp. cucurbitae. Inoculated on ‘Jindi 1’, the strain Fx-1a induced typical fruit rot on the pepo and wilting on seedlings, while negative-controls remained asymptomatic. The impact of this disease on seed quality and yield in zucchini seed production needs to be further studied.

Zucchini (Cucurbita pepo L.) is an important crash crop for producing seeds in Inner Mongolia, China. In August 2021, the harvest season of seed-producing zucchini, fruit rot symptom (cv. Jindi No.1) was found in the Wuyuan region. The incidence of infected fruits of zucchini ranged from 10% to 30% and symptom consisted in 4 to 5 cm diameter lesions where the fruit was in contact with the soil. Ten isolations from six symptomatic fruits were preliminary classified as Fusarium species based on its morphological characters in potato dextrose agar. Phylogenetic tree was constructed by concatenating TEF-1α and RPB2 gene and exhibited the isolates clustered together with the Fusarium solani f. sp. cucurbitae sequences. Pathogenicity tests revealed that two isolates caused over 3 cm diameter lesions on the fruits while negative-controls remained asymptomatic. The colonies reisolated from the leasions were morphologically identical to the original isolates, thus fulfilling Koch’s postulates. Results demonstrated that F. solani f. sp. cucurbitae was the causal agent of fruit rot observed in the field. To our knowledge, this is the first report of fruit rot of seed-producing zucchini caused by F. solani f. sp. cucurbitae in Inner Mongolia, China.

Blackleg disease, caused by Plenodomus biglobosus, presents a significant global threat to production. This pathogen reduces both yield and crop quality in