The ascomycete fungus Venturia inaequalis causes scab disease, a major problem in apple production. The utilization of resistant cultivars is hindered by emerging new pathogen races, which erode their resistance. Increasing our knowledge on the population genetic processes of the fungus can contribute to the development of resistance gene deployment strategies and more durable resistance. We investigated the effect of four scab race indicator cultivars, ‘Gala’ (no R-gene), ‘Golden Delicious’ (Rvi1), ‘Geneva’ (Rvi3, complex), and OR45t132 (Rvi5), on the V. inaequalis population genetic structure and diversity. Sixty-six monosporic fungal isolates from the four cultivars were genotyped with seven simple sequence repeat primers. Furthermore, the partial resistance of the indicators and the pathogenicity profile of the conidia from each host were assessed. The genetic diversity and structure of the investigated V. inaequalis subpopulations correspond to the partial resistance of the original hosts as well as the subpopulations’ pathogenicity profiles. Indicators carrying Rvi3 and Rvi5 had strongly diverged and specialized V. inaequalis populations on them and fewer symptoms on the field. In line with the complete breakdown of the Rvi1 gene, the population from ‘Golden Delicious’ did not segregate from the susceptible ‘Gala’, and virulence towards Rvi1 was present in all subpopulations.

Fungal leaf spot pathogens of cucurbits cause significant yield losses. They cause extensive leaf necroses and defoliation, reducing host photosynthesis. They increase risks of fruit sunscald, and can cause substantial crop damage. Alternaria cucumerina has been recognized as the causal agent of leaf spot disease of cucurbits, and recent studies have identified other Alternaria species, and other emerging pathogens such as Curvularia. This study characterized 25 isolates obtained from infected watermelon and cucumber leaves from Hungary, Spain, and Kosovo. Morphological characterization and molecular analyses using TEF1-α, HIS3, and ITS gene regions identified Alternaria alternata and A. arborescens, and for the first time on this host, the genus Curvularia. Detached leaf assays of ten isolates on 73 watermelon accessions showed variation in isolate pathogenicity. The tested Curvularia isolate was the most aggressive, followed by the A. arborescens and A. alternata isolates, although A. alternata was the most frequently identified species. These results highlight the potential for emerging fungal pathogens causing cucurbit leaf spot, such as Curvularia sp., and show that these fungi can cause damage on economically important plants. This study also showed differing resistance within the watermelon collection, indicating potential for the plant introduction (PI) accessions as sources of resistance breeding.

Despite the inherent high salinity tolerance of mature carob (Ceratonia siliqua L., Fabaceae) trees, young seedlings are particularly vulnerable to salt stress, which can hinder their growth and development. Although hydrogen sulfide (H₂S) has been widely studied as a regulator of salinity tolerance in herbaceous plants, its role in woody legumes remains largely unexplored. This study aimed to explore the potential of hydrogen sulfide (H₂S) pretreatment to enhance the salinity tolerance of young carob seedlings. A pot experiment was conducted using a factorial design to evaluate the effects of sodium hydrosulfide (NaHS, an H₂S donor) at 0, 75, and 200 µM under saline conditions (0, 50, and 100 mM NaCl). The results indicated that H₂S pretreatment enhanced the biomass of both shoots and roots under both saline and non-saline conditions, with the potential to compensate growth loss due to salt stress. Additionally, stress markers such as hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) increased by about 23% and 28%, respectively, in seedlings treated with 75 µM NaHS after exposure to 100 mM NaCl stress. The enhanced salinity stress tolerance was presumably associated with increased antioxidant enzyme activity, including superoxide dismutase (SOD, ≈ 24%), ascorbate peroxidase (APX, ≈ 118%), and peroxidase (POD, ≈ 50%) after 75 µM NaHS pretreatment in plants exposed to 100 mM NaCl. Moreover, NaHS pretreatment reduced sodium ion (Na⁺) accumulation in both leaves and roots. These findings indicate that H₂S enhances the salinity tolerance of carob seedlings, helping them better withstand suboptimal growing conditions.

In 2024 and 2025, leaf spot symptoms were observed in a jujube ( Ziziphus jujuba ) cultivar collection in Hungary. The symptoms manifested as small, brown necrotic spots, a few millimetres in diameter, surrounded by a chlorotic margin, resembling to Alternaria leaf spot. The pathogen was successfully isolated from symptomatic leaves, and was identified as a member of the Alternaria arborescense species complex through morphological characterization and multilocus phylogenetic analysis targeting the ITS, TEF1-α , and Rpb2 gene regions. Artificial inoculations of detached jujube leaves and seedlings reproduced the characteristic disease symptoms, and subsequent reisolation of the fungus fulfilled Koch’s postulates, confirming its pathogenicity. Hence, this study represents the first report of A. arborescense causing jujube leaf spot. The potential impact of A. arborescens on jujube production and the increasing prevalence of Alternaria leaf spot diseases under the changing climatic conditions, underscore the need for further research.

Crop wild relatives of Malus domestica represent exceptional value as breeding resources and ornamental trees, nonetheless their natural populations are un