Fusarium Head Blight Infection Induced Responses of Six Winter Wheat Varieties in Ascorbate-Glutathione Pathway, Photosynthetic Efficiency and Stress Hormones.

Fusarium head blight (FHB) is one of the most studied fungal diseases of wheat, causing massive grain yield and quality losses. This study aimed to extend previous studies on the physiological and biochemical responses of winter wheat to FHB stress in a controlled environment by focusing on the ascorbate-glutathione pathway (AsA-GSH), photosynthetic efficiency, and stress hormone levels, thus providing insight into the possible interactions of different defense mechanisms during infection. The activity of AsA-GSH metabolism was increased in FHB resistant varieties, maintaining the redox state of spikes, and consequently preserving functional photosystem II. Furthermore, carotenoids (Car) were shown to be the major pigments in the photosystem assembly, as they decreased in FHB-stressed spikes of resistant and moderately resistant varieties, compared to controls. Car are also the substrate for the synthesis of abscisic acid (ABA), which acts as a fungal effector and its elevated content leads to increased FHB susceptibility in inoculated spikes. The results of this study contributed to the knowledge of FHB resistance mechanisms and can be used to improve the breeding of FHB resistant varieties, which is considered to be the most effective control measure.

Biochemical Response and Gene Expression to Water Deficit of Croatian Grapevine Cultivars (Vitis vinifera L.) and a Specimen of Vitis sylvestris.

The biochemical response and gene expression in different grapevine cultivars to water deficit are still not well understood. In this study, we investigated the performance of four traditional Croatian Vitis vinifera L. cultivars ('Plavac mali crni', 'Istrian Malvasia', 'Grasevina', and 'Tribidrag'), and one wild (Vitis vinifera subsp. sylvestris) genotype exposed to water deficit (WD) for nine days under semi-controlled conditions in the greenhouse. Sampling for biochemical and gene expression analyses was performed at days six and nine from the beginning of WD treatment. The WD affected the accumulation of metabolites with a significant increase in abscisic acid (ABA), salicylic acid (SA), and proline in the leaves of the stressed genotypes when the WD continued for nine days. Lipid peroxidation (MDA) was not significantly different from that of the control plants after six days of WD, whereas it was significantly lower (297.40 nmol/g dw) in the stressed plants after nine days. The cultivar 'Istrian Malvasia' responded rapidly to the WD and showed the highest and earliest increase in ABA levels (1.16 ng mg-1 dw, i.e., 3.4-fold increase compared to control). 'Grasevina' differed significantly from the other genotypes in SA content at both time points analyzed (six and nine days, 47.26 and 49.63 ng mg-1 dw, respectively). Proline level increased significantly under WD (up to 5-fold at day nine), and proline variation was not genotype driven. The expression of aquaporin genes (TIP2;1 and PIP2;1) was down-regulated in all genotypes, coinciding with the accumulation of ABA. The gene NCED1 (9-cis-epoxycarotenoid dioxygenase) related to ABA was up-regulated in all genotypes under stress conditions and served as a reliable marker of drought stress. This work suggests that the stress response in metabolite synthesis and accumulation is complex, treatment- and genotype-dependent.

Antioxidant and Antiproliferative Activities of Kale (Brassica oleracea L. Var. acephala DC.) and Wild Cabbage (Brassica incana Ten.) Polyphenolic Extracts.

Brassicaceae are rich in healthy phytochemicals that have a positive impact on human health. The aim of this study was to analyze the phenolic compounds and antioxidant and anticancer potential of traditional Croatian kale (Brassica oleracea L. var. acephala DC.) and wild cabbage (Brassica incana Ten.) extracts. The phenolic groups and antioxidant activity were determined by spectrophotometry, selected phenolic compounds (ferulic acid, sinapic acid, salicylic acid, kaempferol, and quercetin) were analyzed by LC-MS/MS, and anticancer potential was evaluated in vitro using HeLa cells. The extracts of both plant species are rich in phenolic compounds and showed significant antioxidant activity at similar levels. LC-MS/MS detected sinapic acid as the most abundant phenolic acid, followed by ferulic acid, while salicylic acid was present at lower concentrations. A comparative analysis showed that wild cabbage contained significantly more sinapic acid, while kale contained more kaempferol and quercetin. Both Brassica extracts at a concentration of 50 µg mL-1 showed an antiproliferative effect on HeLa cells, while they did not affect the proliferation of normal human skin fibroblasts. Wild cabbage extract also showed an antiproliferative effect on HeLa cells at a lower applied concentration of 10 µg mL-1 of extracts. The clonogenic analysis also revealed the inhibitory effect of the extracts on HeLa colony growth.

Morpho-Physiological and Hormonal Response of Winter Wheat Varieties to Drought Stress at Stem Elongation and Anthesis Stages.

Drought stress can significantly reduce wheat growth and development as well as grain yield. This study investigated morpho-physiological and hormonal (abscisic (ABA) and salicylic (SA) acids) responses of six winter wheat varieties during stem elongation and anthesis stage as well grain yield-related traits were measured after harvest. To examine drought response, plants were exposed to moderate non-lethal drought stress by withholding watering for 45 and 65% of the volumetric soil moisture content (VSMC) for 14 days at separate experiments for each of those two growth stages. During the stem elongation phase, ABA was increased, confirming the stress status of plants, and SA showed a tendency to increase, suggesting their role as stress hormones in the regulation of stress response, such as the increase in the number of leaves and tillers in drought stress conditions, and further keeping turgor pressure and osmotic adjustment in leaves. At the anthesis stage, heavier drought stress resulted in ABA accumulation in flag leaves that generated an integrated response of maturation, where ABA was not positively correlated with any of investigated traits. After harvest, the variety Bubnjar, followed by Pepeljuga and Andelka, did not significantly decrease the number of grains per ear and 1000 kernel weight (except Andelka) in drought treatments, thus, declaring them more tolerant to drought. On the other hand, Rujana, Fifi, and particularly Silvija experienced the highest reduction in grain yield-related traits, considering them drought-sensitive varieties.

Comprehensive Volatilome Signature of Various Brassicaceae Species.

To investigate in detail the volatilomes of various Brassicaceae species, landraces, and accessions, and to extract specific volatile markers, volatile aroma compounds were isolated from plant samples by headspace solid-phase microextraction and analyzed by gas chromatography/mass spectrometry (HS-SPME-GC/MS). The data obtained were subjected to uni- and multivariate statistical analysis. In general, two cabbage (Brassica oleracea L. var. capitata) landraces emitted the lowest amounts of volatiles generated in the lipoxygenase (LOX) pathway. Wild species Brassica incana Ten. and Brassica mollis Vis. were characterized by relatively high trans-2-hexenal/cis-3-hexen-1-ol ratio in relation to other investigated samples. A Savoy cabbage (Brassica oleracea L. var. sabauda) cultivar and three kale (Brassica oleracea L. var. acephala) accessions exhibited particular similarities in the composition of LOX volatiles, while the LOX volatilome fraction of B. incana and B. mollis partially coincided with that of another wild species, Diplotaxis tenuifolia L. Regarding volatiles formed in the glucosinolate (GSL) pathway, Savoy cabbage and wild species B. incana, B. mollis, and D. tenuifolia showed more intense emission of isothiocyanates than cabbage and kale. Diplotaxis tenuifolia showed a rather limited production of nitriles. The results of this study contribute to the general knowledge about volatile composition from various Brassicaceae species, which could be exploited for their better valorization. Future studies should focus on the influence of various environmental, cultivation, and post-harvest factors to obtain data with a higher level of applicability in practice.

Application of Long-Chained Auxin Conjugates Influenced Auxin Metabolism and Transcriptome Response in Brassica rapa L. ssp. pekinensis.

Auxin amino acid conjugates are considered to be storage forms of auxins. Previous research has shown that indole-3-acetyl-L-alanine (IAA-Ala), indole-3-propionyl-L-alanine (IPA-Ala) and indole-3-butyryl-L-alanine (IBA-Ala) affect the root growth of Brassica rapa seedlings. To elucidate the potential mechanism of action of the conjugates, we treated B. rapa seedlings with 0.01 mM IAA-, IPA- and IBA-Ala and investigated their effects on the auxin metabolome and transcriptome. IBA-Ala and IPA-Ala caused a significant inhibition of root growth and a decrease in free IAA compared to the control and IAA-Ala treatments. The identification of free auxins IBA and IPA after feeding experiments with IBA-Ala and IPA-Ala, respectively, confirms their hydrolysis in vivo and indicates active auxins responsible for a stronger inhibition of root growth. IBA-Ala caused the induction of most DEGs (807) compared to IPA-Ala (417) and IAA-Ala (371). All treatments caused similar trends in transcription profile changes when compared to control treatments. The majority of auxin-related DEGs were found after IBA-Ala treatment, followed by IPA-Ala and IAA-Ala, which is consistent with the apparent root morphology. In addition to most YUC genes, which showed a tendency to be downregulated, transcripts of auxin-related DEGs that were identified (UGT74E2, GH3.2, SAUR, IAA2, etc.) were more highly expressed after all treatments. Our results are consistent with the hypothesis that the hydrolysis of conjugates and the release of free auxins are responsible for the effects of conjugate treatments. In conclusion, free auxins released by the hydrolysis of all auxin conjugates applied affect gene regulation, auxin homeostasis and ultimately root growth inhibition.

Mechanisms of Kale (Brassica oleracea var. acephala) Tolerance to Individual and Combined Stresses of Drought and Elevated Temperature.

Rising temperatures and pronounced drought are significantly affecting biodiversity worldwide and reducing yields and quality of Brassica crops. To elucidate the mechanisms of tolerance, 33 kale accessions (B. oleracea var. acephala) were evaluated for individual (osmotic and elevated temperature stress) and combined stress (osmotic + temperature). Using root growth, biomass and proline content as reliable markers, accessions were evaluated for stress responses. Four representatives were selected for further investigation (photosynthetic performance, biochemical markers, sugar content, specialized metabolites, transcription level of transcription factors NAC, HSF, DREB and expression of heat shock proteins HSP70 and HSP90): very sensitive (392), moderately sensitive (395), tolerant (404) and most tolerant (411). Accessions more tolerant to stress conditions were characterized by higher basal content of proline, total sugars, glucosinolates and higher transcription of NAC and DREB. Under all stress conditions, 392 was characterized by a significant decrease in biomass, root growth, photosynthesis performance, fructan content, especially under osmotic and combined stress, a significant increase in HSF transcription and HSP accumulation under temperature stress and a significant decrease in NAC transcription under all stresses. The most tolerant accession under all applied stresses, 411 showed the least changes in all analyzed parameters compared with the other accessions.

Influence of Soil Salinity on Selected Element Contents in Different Brassica Species.

Climate changes in coastal regions cause increased soil salinity, a well-known type of environmental stress for a high number of agricultural crop species, including Brassicaceae, whose growth and development, and consequently the crop quality and yield, are affected by salinity stress. The aim of the present study is to investigate the effect of salt stress on micro- and macro-element homeostasis in different Brassica crops. Kale (Brassica oleracea var. acephala), white cabbage (B. oleracea var. capitata) and Chinese cabbage (B. rapa ssp. pekinensis) were grown hydroponically and treated with 200 mmol/L sodium chloride for 24 h to mimic short-term salt stress. The contents of Al, Ca, K, Mg, Na, B, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V and Zn were determined in the roots and leaves of the salt-treated plants and corresponding controls by inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry. While Al, Ca, K, Mg and Na were determined in the mg/g range, the contents of the other elements were found at the µg/g level. A statistical analysis of the obtained data showed that the applied salt treatment significantly influenced the single-element contents in different plant parts. The major elements Ca, K and Mg were mainly unaffected in the more-salt-tolerant kale and white cabbage under salinity stress, while K and Mg were significantly decreased in the more-sensitive Chinese cabbage. The levels of micro-elements were found to be species/variety specific. In general, potentially toxic elements were accumulated in the roots of salt-treated plants to a higher extent than in the corresponding controls.

Low Temperatures Affect the Physiological Status and Phytochemical Content of Flat Leaf Kale (Brassica oleracea var. acephala) Sprouts.

Consumption of plants in the juvenile stage becomes popular because sprouts are easy to grow, and they can be a tasty source of micro- and macro-nutrients and various phytochemicals. However, some environmental factors during sprout growth can affect their characteristics. In this article, we investigated how low temperatures during cultivation (8 °C) and additional exposure to freezing temperatures (-8 °C) affect the physiological status and phytochemical content of kale (Brassica oleracea var. acephala) sprouts compared to the control grown at 21 °C. We conducted five independent laboratory experiments and found that low temperature significantly increased proline content and decreased sprouts yield. In addition, low temperature caused a significant decrease in carotenoid and flavonoid content, while phenolic acid content and total glucosinolates content increased, but individual glucosinolates were differentially affected. Our results indicate that low temperatures affect the physiological status of kale sprouts and affect the content of phytochemicals.

Ferulic Acid and Salicylic Acid Foliar Treatments Reduce Short-Term Salt Stress in Chinese Cabbage by Increasing Phenolic Compounds Accumulation and Photosynthetic Performance.

Salinity stress is one of the most damaging abiotic stresses to plants, causing disturbances in physiological, biochemical, and metabolic processes. The exogenous application of natural metabolites is a useful strategy to reduce the adverse effects of stress on crops. We investigated the effect of foliar application of salicylic acid (SA) and ferulic acid (FA) (10-100 µM) on short-term salt-stressed (150 mM NaCl, 72 h) Chinese cabbage plants. Subsequently, proline level, photosynthetic performance, phenolic metabolites with special focus on selected phenolic acids (sinapic acid (SiA), FA, SA), flavonoids (quercetin (QUE), kaempferol (KAE)), and antioxidant activity were investigated in salt-stressed and phenolic acid-treated plants compared with the corresponding controls. Salt stress caused a significant increase in SA and proline contents, a decrease in phenolic compounds, antioxidant activity, and photosynthetic performance, especially due to the impairment of PSI function. SA and FA treatments, with a concentration of 10 µM, had attenuated effects on salt-stressed plants, causing a decrease in proline and SA level, and indicating that the plants suffered less metabolic disturbance. Polyphenolic compounds, especially FA, SiA, KAE, and QUE, were increased in FA and SA treatments in salt-stressed plants. Consequently, antioxidant activities were increased, and photosynthetic performances were improved. FA resulted in a better ameliorative effect on salt stress compared to SA.

Altered Root Growth, Auxin Metabolism and Distribution in Arabidopsis thaliana Exposed to Salt and Osmotic Stress.

Salt and osmotic stress are the main abiotic stress factors affecting plant root growth and architecture. We investigated the effect of salt (100 mM NaCl) and osmotic (200 mM mannitol) stress on the auxin metabolome by UHPLC-MS/MS, auxin distribution by confocal microscopy, and transcript levels of selected genes by qRT-PCR in Arabidopsis thaliana ecotype Columbia-0 (Col-0) and DR5rev::GFP (DR5) line. During long-term stress (13 days), a stability of the auxin metabolome and a tendency to increase indole-3-acetic acid (IAA) were observed, especially during salt stress. Short-term stress (3 h) caused significant changes in the auxin metabolome, especially NaCl treatment resulted in a significant reduction of IAA. The data derived from auxin profiling were consistent with gene expressions showing the most striking changes in the transcripts of YUC, GH3, and UGT transcripts, suggesting disruption of auxin biosynthesis, but especially in the processes of amide and ester conjugation. These data were consistent with the auxin distribution observed in the DR5 line. Moreover, NaCl treatment caused a redistribution of auxin signals from the quiescent center and the inner layers of the root cap to the epidermal and cortical cells of the root elongation zone. The distribution of PIN proteins was also disrupted by salt stress; in particular, PIN2 was suppressed, even after 5 min of treatment. Based on our results, the DR5 line was more sensitive to the applied stresses than Col-0, although both lines showed similar trends in root morphology, as well as transcriptome and metabolome parameters under stress conditions.

Chilling and Freezing Temperature Stress Differently Influence Glucosinolates Content in Brassica oleracea var. acephala.

Brassica oleracea var. acephala is known to have a strong tolerance to low temperatures, but the protective mechanisms enabling this tolerance are unknown. Simultaneously, this species is rich in health-promoting compounds such as polyphenols, carotenoids, and glucosinolates. We hypothesize that these metabolites play an important role in the ability to adapt to low temperature stress. To test this hypothesis, we exposed plants to chilling (8 °C) and additional freezing (-8 °C) temperatures under controlled laboratory conditions and determined the levels of proline, chlorophylls, carotenoids, polyphenols, and glucosinolates. Compared with that of the control (21 °C), the chilling and freezing temperatures increased the contents of proline, phenolic acids, and flavonoids. Detailed analysis of individual glucosinolates showed that chilling increased the total amount of aliphatic glucosinolates, while freezing increased the total amount of indolic glucosinolates, including the most abundant indolic glucosinolate glucobrassicin. Our data suggest that glucosinolates are involved in protection against low temperature stress. Individual glucosinolate species are likely to be involved in different protective mechanisms because they show different accumulation trends at chilling and freezing temperatures.

The Role of Polyphenols in Abiotic Stress Response: The Influence of Molecular Structure.

Abiotic stressors such as extreme temperatures, drought, flood, light, salt, and heavy metals alter biological diversity and crop production worldwide. Therefore, it is important to know the mechanisms by which plants cope with stress conditions. Polyphenols, which are the largest group of plant-specialized metabolites, are generally recognized as molecules involved in stress protection in plants. This diverse group of metabolites contains various structures, from simple forms consisting of one aromatic ring to more complex ones consisting of large number of polymerized molecules. Consequently, all these molecules, depending on their structure, may show different roles in plant growth, development, and stress protection. In the present review, we aimed to summarize data on how different polyphenol structures influence their biological activity and their roles in abiotic stress responses. We focused our review on phenolic acids, flavonoids, stilbenoids, and lignans.

Involvement of Phenolic Acids in Short-Term Adaptation to Salinity Stress is Species-Specific among Brassicaceae.

Salinity is a major abiotic stress negatively affecting plant growth and consequently crop production. The effects of short-term salt stress were evaluated on seedlings of three globally important Brassica crops-Chinese cabbage (Brassica rapa ssp. pekinensis), white cabbage (Brassica oleracea var. capitata), and kale (Brassica oleracea var. acephala)-with particular focus on phenolic acids. The physiological and biochemical stress parameters in the seedlings and the levels of three main groups of metabolites (total glucosinolates, carotenoids, and phenolics) and individual phenolic acids were determined. The salt treatments caused a dose-dependent reduction in root growth and biomass and an increase in stress parameters (Na+/K+ ratio, reactive oxygen species (ROS) and glutathione (GSH)) in all seedlings but most prominently in Chinese cabbage. Based on PCA, specific metabolites grouped close to the more tolerant species, white cabbage and kale. The highest levels of phenolic acids, particularly hydroxycinnamic acids, were determined in the more tolerant kale and white cabbage. A reduction in caffeic, salicylic, and 4-coumaric acid was found in Chinese cabbage and kale, and an increase in ferulic acid levels was found in kale upon salinity treatments. Phenolic acids are species-specific among Brassicaceae, and some may participate in stress tolerance. Salt-tolerant varieties have higher levels of some phenolic acids and suffer less from metabolic stress disorders under salinity stress.

Early Brassica Crops Responses to Salinity Stress: A Comparative Analysis Between Chinese Cabbage, White Cabbage, and Kale.

Soil salinity is severely affecting crop productivity in many countries, particularly in the Mediterranean area. To evaluate early plant responses to increased salinity and characterize tolerance markers, three important Brassica crops - Chinese cabbage (Brassica rapa ssp. pekinensis), white cabbage (B. oleracea var. capitata) and kale (B. oleracea var. acephala) were subjected to short-term (24 h) salt stress by exposing them to NaCl at concentrations of 50, 100, or 200 mM. Physiological (root growth, photosynthetic performance parameters, and Na+/K+ ratio) and biochemical parameters (proline content and lipid peroxidation as indicated by malondialdehyde, MDA, levels) in the plants' roots and leaves were then measured. Photosynthetic parameters such as the total performance index PItotal (describing the overall efficiency of PSI, PSII and the intersystem electron transport chain) appeared to be the most salinity-sensitive parameter and informative stress marker. This parameter was decreased more strongly in Chinese cabbage than in white cabbage and kale. It indicated that salinity reduced the capacity of the photosynthetic system for efficient energy conversion, particularly in Chinese cabbage. In parallel with the photosynthetic impairments, the Na+/K+ ratio was highest in Chinese cabbage leaves and lowest in kale leaves while kale root is able to keep high Na+/K+ ratio without a significant increase in MDA. Thus Na+/K+ ratio, high in root and low in leaves accompanying with low MDA level is an informative marker of salinity tolerance. The crops' tolerance was positively correlated with levels of the stress hormone abscisic acid (ABA) and negatively correlated with levels of jasmonic acid (JA), and jasmonoyl-L-isoleucine (JA-Ile). Furthermore, salinity induced contrasting changes in levels of the growth-promoting hormones brassinosteroids (BRs). The crop's tolerance was positively correlated with levels of BR precursor typhasterol while negatively with the active BR brassinolide. Principal Component Analysis revealed correlations in observed changes in phytohormones, biochemical, and physiological parameters. Overall, the results show that kale is the most tolerant of the three species and Chinese cabbage the most sensitive to salt stress, and provide holistic indications of the spectrum of tolerance mechanisms involved.

Kale (Brassica oleracea var. acephala) as a superfood: Review of the scientific evidence behind the statement.

Kale (Brassica oleracea var. acephala) is a cruciferous vegetable, characterized by leaves along the stem, which, in recent years, have gained a great popularity as a ´superfood´. Consequently, in a popular culture it is listed in many ´lists of the healthiest vegetables´. Without the doubt, a scientific evidences support the fact that cruciferous vegetables included in human diet can positively affect health and well-being, but remains unclear why kale is declared superior in comparison with other cruciferous. It is questionable if this statement about kale is triggered by scientific evidence or by some other factors. Our review aims to bring an overview of kale's botanical characteristics, agronomic requirements, contemporary and traditional use, macronutrient and phytochemical content and biological activity, in order to point out the reasons for tremendous kale popularity.

Correlations between Phytohormones and Drought Tolerance in Selected Brassica Crops: Chinese Cabbage, White Cabbage and Kale.

Drought is one of the major abiotic stresses affecting the productivity of Brassica crops. To understand the role of phytohormones in drought tolerance, we subjected Chinese cabbage (B. rapa ssp. pekinensis), white cabbage (B. oleracea var. capitata), and kale (B. oleracea var. acephala) to drought and examined the stress response on the physiological, biochemical and hormonal levels. The phytohormones abscisic acid (ABA), auxin indole-3-acetic acid (IAA), brassinosteroids (BRs), cytokinins (CKs), jasmonates (JAs), and salicylic acid (SA) were analyzed by ultra-high-performance liquid chromatography⁻tandem mass spectrometry (UHPLC-MS/MS). Based on the physiological and biochemical markers the Chinese cabbage exhibited the lowest tolerance, followed by the white cabbage, while the kale appeared to be the most tolerant to drought. The drought tolerance of the kale correlated with increased levels of SA, ABA, IAA, CKs iP(R) and cZ(R), and typhasterol (TY), a precursor of active BRs. In contrast, the drought sensitivity of the Chinese cabbage correlated with a significant increase in ABA, JAs and the active BRs castasterol (CS) and brassinolide (BL). The moderately tolerant white cabbage, positioned between the kale and Chinese cabbage, showed more similarity in terms of the phytohormone patterns with the kale. We concluded that the drought tolerance in Brassicaceae is mostly determined by the increased endogenous levels of IAA, CKs, ABA and SA and the decreased levels of active BRs.

Comparative analysis of phytochemicals and activity of endogenous enzymes associated with their stability, bioavailability and food quality in five Brassicaceae sprouts.

Five Brassicaceae sprouts (white cabbage, kale, broccoli, Chinese cabbage, arugula) were comparatively analyzed based on phytochemicals (polyphenols, glucosinolates, carotenoids, chlorophylls, ascorbic acid) content and accompanying enzymes associated with phytochemical stability and bioavailability (peroxidases, myrosinase, and polyphenol-oxidase) that consequently impact food quality. Significantly high content of polyphenols and glucosinolates, as well as a high antioxidant activity were found in white cabbage, followed by kale sprouts. In addition, white cabbage contained higher amount of fibers and lower polyphenol-oxidase activity which potentially indicates prevention of browning and consequently better sprout quality. Arugula and broccoli showed higher activity of myrosinase that may result in higher bioavailability of active glucosinolates forms. According to our data, sprouts are cheap, easy- and fast-growing source of phytochemicals but also they are characterized by different endogenous enzymes activity. Consequently, this parameter should also be taken into consideration in the studies related to the health benefits of the plant-based food.

Short-term salt stress in Brassica rapa seedlings causes alterations in auxin metabolism.

Salinity is one of major abiotic stresses affecting Brassica crop production. Here we present investigations into the physiological, biochemical, and hormonal components of the short-term salinity stress response in Chinese cabbage seedlings, with particular emphasis on the biosynthesis and metabolism of auxin indole-3-acetic acid (IAA). Upon salinity treatments (50-200 mM NaCl) IAA level was elevated in a dose dependent manner reaching 1.6-fold increase at the most severe salt treatment in comparison to the control. IAA precursor profiling suggested that salinity activated the indole-3-acetamide and indole-3-acetaldoxime biosynthetic pathways while suppressing the indole-3-pyruvic acid pathway. Levels of the IAA catabolites 2-oxoindole-3-acetic acid and indole-3-acetic acid-aspartate increased 1.7- and 2.0-fold, respectively, under the most severe treatment, in parallel with those of IAA. Conversely, levels of the ester conjugate indole-3-acetyl-1-O-ß-d-glucose and its catabolite 2-oxoindole-3-acetyl-1-O-ß-d-glucose decreased 2.5- and 7.0-fold, respectively. The concentrations of stress hormones including jasmonic acid and jasmonoyl-isoleucine (JA and JA-Ile), salicylic acid (SA) and abscisic acid (ABA) confirmed the stress induced by salt treatment: levels of JA and JA-Ile increased strongly under the mildest treatment, ABA only increased under the most severe treatment, and SA levels decreased dose-dependently. These hormonal changes were related to the observed changes in biochemical stress markers upon salt treatments: reductions in seedling fresh weight and root growth, decreased photosynthesis rate, increased levels of reactive oxygen species, and elevated proline content and the Na+/K+ ratio. Correlations among auxin profile and biochemical stress markers were discussed based on Pearson's coefficients and principal component analysis (PCA).

Formation and morphogenesis of a cuttlebone's aragonite biomineral structures for the common cuttlefish (Sepia officinalis) on the nanoscale: Revisited.

This study describes and examines the structural and morphological properties of the hierarchically organized, aragonite cuttlebone forms for the common cuttlefish (Sepia officinalis, L.), including its main structural parts, the dorsal shield, and the chambers. Specifically, it complements the mechanism for the self-organized formation of aragonite, identifies the presence, and determines the role of soluble organic matrix (SOM) proteins in the morphogenesis of the cuttlebone's biomineral structures on the nanoscale. The structure and morphology of the cuttlebone were examined using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM), and their thermal properties by thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA). Proteins from the SOM were investigated using two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (2D-PAGE), matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS), nano liquid chromatography tandem mass spectrometry (nano-LC ESI-MS) and Edman degradation. The results showed that the cuttlebone exhibited several diverse biomineral structures characterized by complex morphologies. Their formation is governed by the organic matrix, particularly proteins, which at the earliest stage of development provide templates for the initial extracellular nucleation of the aragonite nanocrystals. This is followed by a bottom-up morphogenesis, based on the nanoscale oriented aggregation and coalescence of primarily formed aragonite nanograins, which results in the hierarchically organized, nanostructured, aragonite forms. The molecular masses of the most pronounced SOM proteins from the dorsal shield were about 10, 15, 40 and 60kDa, while from the chambers they were 10, 20, 25, 30 and 45kDa. Peptide fragments corresponding to Sep7, Sep8, chitin synthase 1, ficoline-2, polyubiquitin and the ubiquitin carboxyl-terminal hydrolase 32-like protein were detected in the SOM, with these proteins having functional properties related to the biomineralization processes. In general, there are mostly acidic proteins present in alternatively glycosylated forms, which are common attributes of biomineralization-related proteins.