Heavy losses incited yearly by Alternaria brassicicola on the vegetable Brassicaceae have prompted our search for sources of genetic resistance against the pathogen and the resultant disease, dark leaf spot. We optimized several parameters to test the performance of the plants under artificial inoculations with this pathogen, including leaf age and position, inoculum concentration, and incubation temperature. Using these optimized conditions, we screened a collection of 38 Brassicaceae cultigens with two methods (detached leaf and seedlings). Our results show that either method can be used for the A. brassicicola resistance breeding, and that the plant genotype was crucial in determining its response to the pathogen. The bio-assays for A. brassicicola resistance were run under more stringent lab conditions than the field tests (natural epidemics), resulting in identification of two interspecific hybrids that might be used in breeding programs. Based on the results of the biochemical analyses, reactive oxygen species and red-ox enzymes interplay has been suggested to determine the outcome of the plant-A. brassicicola interplay. Confocal microscopy analyses of the leaf samples provided data on the pathogen mode of infection: Direct epidermal infection or stomatal attack were related to plant resistance level against A. brassicicola among the cultigens tested. Further, the microscopic analyses suggested rapid actin network activation of the host cells around the papillas deposited under the pathogen appressorium.

Interspecific hybridization between B. oleracea inbred lines of head cabbage, Brussels sprouts, kale and B. taurica and inbred lines of rapeseed (B. napus L.) were performed aiming at the development of the new sources of genetic variability of vegetable Brassicas. Using conventional crossings and the embryo-rescue techniques the following interspecific hybrids were developed: 11 genotypes of F₁ generation, 18 genotypes of F₂ and F₁ × F₂ generations (produced after self- and cross-pollination of interspecific F₁ hybrids), 10 plants of the BC₁ generation (resulted from crossing head cabbage cytoplasmic male-sterile lines with interspecific hybrids of the F₂ and F₁ generations) and 8 plants of BC₁ × (F₁ × F₂). No viable seeds of the BC₂ generation (B. oleracea) were obtained due to the strong incompatibility and high mortality of embryos. The morphological characteristics during the vegetative and generative stages, pollen characteristics, seed development and propagation, nuclear DNA contents and genome compositions of interspecific hybrids were analyzed. All the interspecific F₁ hybrids were male-fertile with a majority of undeveloped and malformed pollen grains. They showed intermediate values for morphological traits and nuclear DNA contents and had nearly triploid chromosomal numbers (27 to 29) compared with parental lines. The F₂ generation had a doubled nuclear DNA content, with 52 and 56 chromosomes, indicating their allohexaploid nature. F₂ hybrids were characterized by a high heterosis of morphological characteristics, viable pollen and good seed development. F₁ × F₂ hybrids were male-fertile with a diversified DNA content and intermediate pollen viability. BC₁ plants were male-sterile with an intermediate nuclear DNA content between the F₂ and head cabbage, having 28 to 38 chromosomes. Plants of the BC₁ × (F₁ × F₂) generation were in majority male-fertile with 38–46 chromosomes, high seed set, high heterosis and intermediate values for morphological traits. The obtained interspecific hybrids are valuable as new germplasm for improving Brassica-breeding programs.

During 2011–2014, three self-compatible Chinese cabbage inbred lines (Brassica rapa, genome AA 2n = 20) were sexually hybridised with cytoplasmic male-sterile (CMS Ogu-INRA) and fertile lines of rapeseed (Brassica napus var. oleifera, genome AACC 2n = 38). Interspecific F₁ hybrids and their consecutive back-crosses (BCs) toward B. rapa were obtained, and their morphological and commercial characteristics, as well as their ability for generative propagation, were analysed. Cytometric and morphological analyses confirmed the interspecific character of the F₁ hybrids in comparison with B. napus and B. rapa parental lines. All interspecific F₁ hybrids had intermediate morphological characteristics typical of both parental components in the generative and vegetative stages. The F₁ hybrids of CMS B. napus × B. rapa were sterile, as were those of fertile B. napus × B. rapa. Good seed productivity from CMS B. napus × B. rapa and consecutive back-cross 1 (BC₁)–BC₃ generations with Chinese cabbage as the recurrent parent was obtained. Plants of the BC₁ generation of CMS B. napus × B. rapa were sterile and had highly diversified morphological characteristics, both in the vegetative and generative phases. The BC₃ generation of CMS B. rapa was also sterile and more uniform than BC₁, with good vigour and most of the typical Chinese cabbage agronomic traits. As a result, a collection of Chinese cabbage genotypes having the CMS trait, which is valuable for the breeding of commercial F₁ hybrids, was obtained for the first time in Poland.

Climate change necessitates the development of improved crops capable of withstanding future weather patterns. Carrots (Daucus carota L.), a crucial vegetable crop of global importance, face unique challenges in seed germination and seedling development due to their complex pollination biology and outcrossing reproduction mode with severe inbreeding depression if selfed. This study investigated the effects of salinity and drought stress on carrot seed germination and seedling development, with focus on the roles of seed priming, cellular processes inhibitors, and biochemical responses. Seed priming agents were hypothesized to enhance stress tolerance by modulating specific cellular and biochemical pathways, such as improving osmotic balance, enhancing antioxidant defense mechanisms, and activating stress-responsive genes. We also hypothesized that specific cellular processes and biochemical pathways influence the germination and early seedling growth of carrot seeds under salinity or drought stress. To test that hypothesis, we evaluated the effects of seed priming with various agents (e.g., water, NaCl, PEG, GA₃) on germination rates and seedling vigor. Additionally, we investigated the impact of inhibitors (actinomycin D—inhibitor of transcription, cycloheximide—inhibitor of translation, hydroxyurea—inhibitor of DNA synthesis, cytochalasin—inhibitor of actin polymerization) on seed germination under stress conditions. Biochemical responses, including reactive oxygen species (ROS) levels and antioxidant enzyme activities, were analyzed to identify genotype-specific adaptations indicative of stress tolerance. Our results revealed significant variability in germination rates and seedling growth among the studied carrot experimental lines and commercial cultivars under salinity or drought stress Seed priming enhanced germination and seedling vigor by up to 35% under salinity stress and 28% under drought stress, with notable differences observed across the priming agents. The application of inhibitors highlighted the involvement of specific cellular processes in regulation of seed germination under stress. For instance, actinomycin D reduced germination by 40% under salinity stress. Biochemical analyses indicated genotype-specific responses, with variations in ROS levels and antioxidant enzyme activities such as superoxide dismutase and peroxidase. ROS levels increased by 50% under drought stress, whereas antioxidant enzyme activities varied substantially among genotypes. These findings underscored the importance of genotype-specific adaptations in conferring salinity or drought tolerance in carrot seedlings. Future research integrating omics approaches (e.g., transcriptomics, proteomics, metabolomics) will provide deeper insights into the molecular mechanisms that regulate stress tolerance, to aid in the development of more resilient carrot varieties suitable for cultivation under adverse environmental conditions.

Improvement of the male sterile cauliflower genotypes with Brassica nigra cytoplasm (CMS) according to ability for generative propagation and quality of agronomical traits was performed in former Research Institute of Vegetable Crops, presently Institute of Horticulture, Skierniewice, Poland in the years of 2002-2010. Cauliflower CMS lines and their fertile maintainers were back-crossed with good quality cauliflower breeding lines followed by the stabilization of sterility/or rf, rf nuclear genes in consecutive generations. The presence of untypically developed plants with chimeral generative stacks or partially fertile flowers among segregating test-cross progeny of improved maintainers may suggest the presence of some non-allelic genetic factors modifying the fertility/sterility character for a part of the plants. As a result CMS genotypes with B. nigra cytoplasm and their maintainers with improved quality, significantly higher seeding index, and lower level of flower deformations were obtained.