Oomycetes in the genus Hyaloperonospora cause severe downy mildew that threatens the quality and yield of leafy vegetables in the Brassicaceae family. During 2022 and 2023, infected plant samples were collected from multiple fields across California's Central Coast, and a total of 26 downy mildew pathogen isolates were obtained. Morphological characteristics and molecular analyses based on ITS rDNA and cox2 mtDNA gene sequences identified the isolates as Hyaloperonospora brassicae, H. diplotaxidis, and H. erucae. To further evaluate the host specificity of these pathogens, one representative isolate from each species was selected and inoculated onto a group of commonly grown Brassicaceae crops. H. brassicae, originally isolated from Brassica oleracea, caused 45.8% disease severity in B. oleracea, while disease severity was significantly lower on wild arugula (Diplotaxis tenuifolia, 1.5%) and cultivated arugula (Eruca vesicaria, 0.0%). Similarly, H. diplotaxidis, originally isolated from wild arugula, caused 26.3% disease severity in wild arugula, compared to 2.0% on cultivated arugula and 0.3% in B. oleracea. H. erucae, derived from cultivated arugula, caused 10.4% disease severity on cultivated arugula, 1.4% on wild arugula, and only 0.6% on B. oleracea. This study underscores the host specificity of downy mildew pathogens while also suggesting a potential risk of cross-infection under favorable conditions. These findings may help growers optimize their cropping systems to enhance downy mildew management in the field.

New achievements in tissue culture of the vegetable and medicinal brassica Diplotaxis tenuifolia (L.) DC: Axillary shoot proliferation, somatic embryogenesis and histological analysis, and polyphenolic compounds profile of in vitro and acclimatized plants

Climate change is resulting in increasingly variable weather patterns with spikes of high temperatures adversely affecting crop production. Here the effect of elevated temperature just before harvest was investigated in wild rocket (Diplotaxis tenuifolia (L.) DC.), a popular brassicaceous salad. The key aim was to investigate how pre-harvest stress affects postharvest responses. Mature rocket plants were subjected to 3 days of elevated day time temperature (35 °C) before harvest. Leaves were then stored at 6 °C to mimic postharvest supply chain conditions. Physiological data were collected at harvest and after 7, 14 and 21 days of storage. Volatile organic compounds (VOCs) were analysed by gas chromatography mass spectrometry, changes in metabolite profiles were analysed through flow injection electrospray high-resolution mass spectroscopy, gene expression was assessed by RNAseq and real time PCR. Transcriptomic analysis showed a mild heat stress signature affecting both metabolic and regulatory genes, including those related to hormone signalling. Models for effects on circadian clock genes and regulation of cold/dark stress responses are derived based on Arabidopsis thaliana pathways. After 7 days of storage, there were also significant effects of the pre-harvest heat stress on leaf VOC profiles, with distinct patterns compared to those at harvest. The metabolome was also affected after 7 days of storage, with specific effects on several lipid classes, amino acids and sugars. However, the direction of gene expression changes did not always match effects on VOCs. After 21 days of storage, pre-harvest heat stress adversely affected chlorophyll content and photosynthetic capacity, promoted ion leakage, and resulted in increased stomatal closure. Cold storage affects the physiology, gene expression and metabolome of rocket leaves and these effects are perturbed by exposure to heat stress before harvest.

Enhanced growth and photosynthetic efficiency in wild rocket (Diplotaxis tenuifolia L.) following multi-species microalgal biostimulant application.

Perennial wall rocket (Diplotaxis tenuifolia L.—DC.) exhibits genotype-dependent responses to biostimulant applications, which have not yet been deeply investigated. A two-year greenhouse factorial experiment was carried out to assess the interactions between five cultivars (Mars, Naples, Tricia, Venice, and Olivetta), three biostimulant formulations (Cystoseira tamariscifolia L. extract; a commercial legume-derived protein hydrolysate, “Dynamic”; and Spirulina platensis extract) plus an untreated control, and three crop cycles (autumn, autumn–winter, and winter) on leaf yield and dry matter, organic acids, colorimetric parameters, hydrophilic and lipophilic antioxidant activities, nitrate concentration, nitrogen use efficiency, and mineral composition, using a split plot design with three replicates. Protein hydrolysate significantly enhanced yield and nitrogen use efficiency in Mars (+26%), Naples (+25.6%), Tricia (+25%), and Olivetta (+26%) compared to the control, while Spirulina platensis increased the mentioned parameters only in Venice (+36.2%). Nitrate accumulation was reduced by biostimulant application just in Venice, indicating genotype-dependent nitrogen metabolism responses. The findings of the present research demonstrate that the biostimulant efficacy in perennial wall rocket is mainly ruled by genotypic factors, and the appropriate combinations between the two mentioned experimental factors allow for optimization of leaf yield and quality while maintaining nitrate concentration under the regulation thresholds.

Effects of Digestate from Biogas on Agronomic Traits, Functional and Health Properties of Hydroponic Cultivation of Rocket (Diplotaxis tenuifolia L.) and Parsley (Petroselinum crispum Mill.)

Arugula leaves (Diplotaxis tenuifolia L. and Eruca sativa L.) are a must-have ingredient in ready-to-eat salads, as they are prized for their appearance, taste, and flavor. The nutraceutical properties of this leafy vegetable are attributed to the presence of valuable secondary metabolites, such as phenolic acids and glucosinolates. Using UHPLC-Q-Orbitrap HRMS analysis and ion chromatography, we characterized the content of phenolic acids, glucosinolates, nitrates, and organic acids in organic arugula [Diplotaxis tenuifolia (L.) DC] and evaluated how the foliar application of three different non-microbial biostimulants (a seaweed extract, a vegetable protein hydrolysate, and a tropical plant extract) modulated the expression of these. Although the application of vegetable protein hydrolysate increased, compared to control plants, the nitrate content, the application of the same biostimulant increased the total content of glucosinolates and phenolic acid derivatives by 5.2 and 17.2%. Specifically, the foliar application of the plant-based biostimulant hydrolyzed protein significantly increased the content of glucoerucin (+22.9%), glucocheirolin (+76.8%), and ferulic acid (+94.1%). The highest values of flavonoid derivatives (173.03 μg g-1 dw) were recorded from plants subjected to the exogenous application of seaweed extract. The results obtained underscore how biostimulants, depending on their origin and composition, can be exploited not only to improve agronomic performance but also to enhance the nutraceutical content of vegetables, guaranteeing end consumers a product with premium quality characteristics.

Vascular wilt of lettuce is caused by strains of the Fusarium oxysporum species complex. According to their biological activity, these strains are members of the forma specialis lactucae (FOL). The aim of this study was to characterize strains of F. oxysporum isolated from lettuce in Italy and other countries, belonging to the four currently known races. Strains were analyzed based on pathogenicity on different hosts and a combined phylogenetic analysis of rpb2, tef-1α, cmdA, and tub2 genes. For uncharacterized strains, the race was determined through pathogenicity tests with a set of differential lettuce cultivars for races 1 and 4. To assess the host range, pathogenicity tests were performed on five species: lettuce (Lactuca sativa), lamb's lettuce (Valerianella locusta), spinach (Spinacia oleracea), wild rocket (Diplotaxis tenuifolia), and cultivated rocket (Eruca sativa). Most FOL strains were pathogenic on lettuce with different levels of disease severity; in particular, FOL races 3 and 4 showed the highest level of virulence on lettuce. FOL races 3 and 4 were pathogenic both on lettuce and lamb's lettuce, whereas races 1 and 2 were pathogenic only on lettuce. Furthermore, this study identified the first occurrence of FOL race 4 in Italy to 2016, as the strain FOL 1/16 was assigned to race 4. Results of multigene phylogenetic analysis showed that FOL races 1 and 4 cluster with the species F. curvatum, strains of race 2 with F. curvatum and F. odoratissimum, and strains of race 3 with F. cugenangense. Phylogenetically, race 4 is very close to race 1, but it showed more similarities to race 3 for host range and virulence. This study shows for the first time a broader host range for races 3 and 4 of FOL. The results demonstrate that phylogenetic analysis permits the separation of some races of FOL, but phylogenetic classification alone is insufficient for conclusive separation of races; therefore, it should be accompanied by biological assays based on pathogenicity.

Untargeted HPLC metabolomic profiling and antioxidant activity of wild rocket’s (Diplotaxis tenuifolia (L.) DC.) edible leaves influenced by biofortification, hybrid varieties and harvest time

This study aimed to evaluate the insecticidal, enzymatic, antimicrobial activities, and phytochemical composition of extracts derived from the flowers and leaves of Diplotaxis tenuifolia (DTF and DTL) grown in gypsum-rich soils of Çankırı, utilizing various solvents. LC-MS/MS analysis identified vanillic acid as the major component in the Diplotaxis tenuifolia flower ethyl acetate (DTF-EA), Diplotaxis tenuifolia flower acetone (DTF-Ace), Diplotaxis tenuifolia leaf (DTL-EA), and Diplotaxis tenuifolia leaf acetone (DTL-Ace) extracts, naringin in Diplotaxis tenuifolia leaf n-butanol (DTL-nBu), and hesperidin in Diplotaxis tenuifolia flower n-butanol (DTF-nBu). The DTF-EA extract showed high efficacy in insecticidal assays against Sitophilus granarius and Rhizopertha dominica, achieving 90% and 83.3% mortality, respectively. Similarly, the DTF-Ace extract exhibited 86.6% and 66% mortality against S. granarius and R. dominica, respectively. Enzyme inhibition assays revealed that the DTF-EA extract exhibited potent inhibitory effects against xanthine oxidase (IC50: 27.83 µg/ml) and tyrosinase (IC50: 58.25 µg/ml), surpassing standard inhibitors such as acarbose. In antimicrobial assays, the DTF-EA extract demonstrated broad-spectrum antibacterial activity, exhibiting inhibition zones of 16.5, 15.5, 12.9, and 12.4 mm against Pseudomonas aeruginosa, Listeria monocytogenes, Bacillus cereus, and Salmonella enterica, respectively. The DTL-EA extract displayed significant activity against Escherichia coli (13.1 mm), while the DTL-Ace extract was most effective against Pseudomonas fluorescens (13.3 mm). These findings suggest that D. tenuifolia extracts possess notable antibacterial, insecticidal, and enzyme inhibitory activities, highlighting their potential as natural therapeutic agents and eco-friendly pest control and microbial management alternatives.

The development of sustainable seed coating formulations is essential to enhance crop performance while reducing reliance on synthetic inputs. This study evaluates biochar-enriched coatings incorporating olive pomace, buffalo digestate, and microbial consortia from Fagus, Quercus, and Pinus forest litters, including Trichoderma harzianum, for their effects on seed germination and plant growth. Four crops (Diplotaxis tenuifolia, Lactuca sativa, Solanum lycopersicum, and Zea mays) were tested through germination assays and field trials. Treatments containing digestate or pomace alone significantly reduced germination and seedling growth in D. tenuifolia and L. sativa (below 25%, compared to control), due to the phytotoxic effects of ammonia, salts, and polyphenols. In contrast, biochar-based coatings mitigated these effects, enhancing germination and root elongation. The addition of T. harzianum further improved seedling establishment, likely by enhancing nutrient uptake and suppressing soilborne pathogens, with increases exceeding 100% (compared to control). Field trials confirmed these findings, showing that biochar–T. harzianum combinations improved both shoot and root biomass, particularly in L. sativa and S. lycopersicum. Z. mays displayed greater tolerance to raw by-products, though biochar remained essential for optimal growth. While forest-derived microbial consortia supported microbial balance, their effect on biomass was less pronounced. These results highlight the potential of biochar-based coatings, especially when combined with T. harzianum, as sustainable alternatives to conventional seed treatments.

Diplotaxis tenuifolia, a species with high nutritional value, was recently introduced in Romania, making in-depth research necessary to develop an efficient cultivation technology to increase agronomic and economic potential. Therefore, the present study aimed to evaluate the influence of three mulch treatments-white polyethylene film (WLDPE), black polyethylene film (BLDPE), and nonmulched (NM)-along with three fertilization regimes-organic (OF), chemical (ChF), and nonfertilized (NF)-on the yield and quality of the Bologna cultivar of perennial wall-rocket under the climatic conditions of northeastern Romania. The results showed that mulching with white polyethylene films significantly increased the CO2 assimilation rate, although it did not lead to substantial differences in agro-morphological traits compared to the non-mulched variant. However, plants grown under WLDPE exhibited a significantly higher leaf area index and yield than those under BLDPE mulch. In contrast, BLDPE mulch had a positive effect on dry matter accumulation and β-carotene content. The variations in fertilization regime had no significant impact on most traits analyzed. Significant differences were noted in the CO2 assimilation rate and DPPH antioxidant activity, with organic fertilization increasing CO2 assimilation and decreasing DPPH activity compared to chemical and unfertilized regimes. Furthermore, the interaction between mulching practices and fertilization regimes revealed significant influences on the physiological performance and phytochemical composition of perennial wall-rocket. The highest CO2 assimilation rate and lowest antioxidant activity were recorded in the WLDPE × OF combination, suggesting improved photosynthetic efficiency and a reduced oxidative response resulting from the synergistic effects of reflective mulching and organic fertilization. In contrast, the Bologna cultivar experienced the greatest oxidative stress under the unfertilized regime, with the most pronounced effects observed under no mulching.

Plants use photosynthesis to build biomass and different mechanisms of photosynthesis have evolved. The common C3 pathway has several drawbacks, which are a limitation for global agriculture. The C2 pathway has evolved to harness photorespiration to increase CO2 for the Calvin cycle, while allowing stomata to close more often to limit water loss. C2 photosynthesis is a bioengineering target for improving agricultural, but is largely untested due to species rarity. We tested leaf gas exchange, stomatal anatomy and biomass production between arugula species with different photosynthetic pathways (C2 - Diplotaxis tenuifolia and C3 -Eruca sativa) in a sustainable aquaponics system. Aquaponics provide plants with nutrients and water from fish efflux, reducing water and nutrient stress typical of traditional agriculture. We also grew individuals of each species in soil for comparison with aquaponics. We hypothesized that species in aquaponics would increase stomatal conductance, resulting in higher rates of photosynthesis and growth. We also hypothesized that C2 plants would outperform C3 plants in aquaponics compared to soil because of the potential capacity to better optimize stomatal behavior. For both species, increases in stomatal conductance were detected in aquaponics plants. Additionally, Diplotaxis tenuifolia (C2) exhibited increased stomatal density in aquaponics compared to soil, while Eruca sativa (C3) did not. Surprisingly, this did not lead to increased photosynthesis nor biomass improvement in aquaponics plants for either species. More work is needed, including additional leaf anatomical and stoichiometric data, to evaluate the efficacy of using the C2 pathway as a tool to improve agriculture.

Plant invasion risk assessment in Argentina's arid and semi-arid rangelands.

The biofortification of leafy vegetables with selenium (Se) and iodine (I) provides the basis for the Se/I status optimization and preservation of human health. The effect of foliar Se, I, and Se + I supply in three different crop cycles (autumn, autumn–winter, and winter) on yield, quality, and mineral composition of wall rocket leaves was investigated using biochemical and ICP-MS methods of analysis. Joint foliar supply with selenate/iodide increased yield, antioxidant activity, total phenolic, ascorbic acid, and protein levels by 1.63, 1.24, 1.22, 1.25, and 1.50 times, respectively, and the content of Ca, Mg, P, K, Fe, Cu, and Zn by 1.27, 1.24, 1.35, 1.46, 3.67, 2.76, and 1.44 times, respectively. High correlations between Se, antioxidants, P, Mg, and Ca (r > 0.80) as well as between yield and K/protein content were recorded. Despite a significant decrease in yield, protein, and K, Fe, Cu, and Mn contents in the third crop cycle, compared to the first one, 50 g of wall rocket biofortified with Se/I may provide up to 100% of the Se adequate consumption level, 34.3% of I, 9% of K, 24% of Fe, and 17.7% Ca. The results of the present research confirm the high efficiency of Se/I supply to produce D. tenuifolia leaves as a new functional food.

Two different produced and packaged commercial typologies of pomegranate juice were analyzed for their physicochemical, nutritional, and biological properties. The effects of classical pasteurization (PJ) and high-pressure processing (HP), applied during the productive cycle, were evaluated through several advanced analytical methods, such as CIEL*a*b* colorimetry, HPLC-DAD, DI-ESI-MS and MS/MS, and NMR analyses. Moreover, the exerted biological activity of the two pomegranate juices was monitored through Total Phenolic and Total Flavonoid Contents, antiradical, antioxidant and chelating activity. The potential inhibition of key enzymes of degenerative processes (cholinesterases, tyrosinase) and diabetes (amylase, glucosidase), the allelopathy toward Cichorium intybus, Dicondra repens, and Diplotaxis tenuifolia, and the in vivo toxicity on brine shrimp were also evaluated. The two different applied processing techniques analyzed impacted the bioactive compound's preservation differently, modifying the phytocomplex profile. HP significantly degrades punicalins and punicalagins, better preserving anthocyanins, if compared to PJ's impact. Sensory qualities, antioxidant activity, enzymatic inhibition, and ecotoxicological potential were differently impacted by the two applied processes. The obtained results can be beneficial for finding the optimal processing conditions that balance microbial safety with nutritional value preservation, contributing to the development of healthy pomegranate juice products.

Interaction effect of planting time, mulching and fertilization on perennial wall-rocket

IntroductionThe non-thermal plasma (NTP) technique has been suggested as a sustainable horticultural practice to promote biomass accumulation, nutrient uptake, N metabolism, and disease prevention in plants. In particular, the potentiality of this technique to promote the natural accumulation of nutrients into plants deserve to be explored as input saving is strongly recommended in the horticultural sector.MethodsThe nutrient solution supplied to a red coloured variety of rocket salad [Diplotaxis tenuifolia (L.) DC. ‘Dragon’s Tongue’] grown in a hydroponic close loop system was treated with NTP. Low, medium, and high concentrations of N (i.e., 1, 10, and 20 mM) of the nutrient solution were tested in control (no NTP) or NTP treated conditions in two consecutive growing cycles. Results and discussionResults highlighted a N-dependent effect of NTP treatment showing a biomass stimulation at 10 mM N while negative effects of this technique at 1 and 20mM N. The biomass boosting of NTP found at 10 mMN coupled with an increase in K and Zn showing positive effects also on the nutraceutical aspects. Interestingly, different mechanisms seemed to be involved in the detrimental effects found at low and high N levels, i.e., a lower sensibility to N deficiency at 1 mM and a synergic negative effect of N and NTP in promoting oxidative stress at 20 mM.

Wild rocket (Diplotaxis tenuifolia (L.) DC cv. Dallas) is a leafy green vegetable appreciated for its pungent taste and healthy properties, often consumed as a ready-to-eat product. The cultivation system is crucial in determining the overall quality, while postharvest storage is fundamental for preserving nutritional quality, phytochemicals, and vitamins. This study aimed to investigate the phytochemical content and microbiological quality of soilless (SS) and soil-bound (SB) wild rocket during cold postharvest storage under blue, red, and green Light Emitting Diode (LED). Blue LED increased chlorophylls and carotenoids in SB after two days of storage, and chlorophyll a in SS after seven days. Furthermore, it reduced H2O2 levels after two days (SS and SB) and lipid peroxidation in SB. Red LED increased phenols in both SS and SB but was detrimental to chlorophyll, carotenoids, and oxidative markers. Green LED had less significant effects. Microbiological growth varied with LED treatment: green light increased mesophilic bacteria in SB, and red light did so in SS by day four, while blue light reduced bacterial growth at the end of storage. Overall, Blue LED was the most effective LED in preserving postharvest quality. Soilless cultivation was particularly beneficial in reducing lipid peroxidation and maintaining cell membrane integrity during long-term storage, and it might also be more effective in preserving ascorbic acid. Conversely, soil-bound cultivation methods could enhance initial polyphenol content or better preserve it during early storage. This study highlights the complex interplay of pre-harvest conditions, postharvest quality, and shelf-life performance.

Tailor-made green composts with suppressive properties against tracheofusariosis of wild rocket (Diplotaxis tenuifolia): Useful option for sustainable circular horticulture