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Glucosinolates are precursors of bioactive and health-promoting isothiocyanates (ITCs). Upon enzymatic hydrolysis, Brassica vegetables, such as cabbage, also often yield nitriles and epithionitriles as main products next to ITCs. Here, we show that amines can be additional main enzymatic hydrolysis products of glucosinolates in Brassica vegetables. We propose that a plant endogenous ITC hydrolase (ITCase) is responsible for the enzymatic-like conversion of ITCs to amines in cabbage samples. This ITCase seems to have high activity towards alkenyl ITCs like allyl ITC and lower activity towards methylthioalkyl ITCs, and not to converting methylsulfinylalkyl ITCs like sulforaphane. In contrast, during heat treatment of homogenized cabbage material, methylsulfinylalkylamine levels increased by 400 % after 2 h of heating, which is likely due to thermal decomposition of ITCs, whereas alkenyl amine levels did not change due to heat treatment. The results show that amines from glucosinolates are part of the human diet.

We profiled the grain oligosaccharide content of 154 two-row spring barley genotypes and quantified 27 compounds, mainly inulin- and neoseries-type fructans, showing differential abundance. Clustering revealed two profile groups where the ‘high’ set contained greater amounts of sugar monomers, sucrose, and overall fructans, but lower fructosylraffinose. A genome-wide association study (GWAS) identified a significant association for the variability of two fructan types: neoseries-DP7 and inulin-DP9, which showed increased strength when applying a novel compound ratio-GWAS approach. Gene models within this region included three known fructan biosynthesis genes (fructan:fructan 1-fructosyltransferase, sucrose:sucrose 1-fructosyltransferase, and sucrose:fructan 6-fructosyltransferase). Two other genes in this region, 6(G)-fructosyltransferase and vacuolar invertase1, have not previously been linked to fructan biosynthesis and showed expression patterns distinct from those of the other three genes, including exclusive expression of 6(G)-fructosyltransferase in outer grain tissues at the storage phase. From exome capture data, several single nucleotide polymorphisms related to inulin- and neoseries-type fructan variability were identified in fructan:fructan 1-fructosyltransferase and 6(G)-fructosyltransferase genes. Co-expression analyses uncovered potential regulators of fructan biosynthesis including transcription factors. Our results provide the first scientific evidence for the distinct biosynthesis of neoseries-type fructans during barley grain maturation and reveal novel gene candidates likely to be involved in the differential biosynthesis of various types of fructan in barley.

Capturing the diverse microbiota from healthy and/or stress resilient plants for further preservation and transfer to unproductive and pathogen overloaded soils, might be a tool to restore disturbed plant–microbe interactions. Here, we introduce Aswan Pink Clay as a low-cost technology for capturing and storing the living root microbiota. Clay chips were incorporated into the growth milieu of barley plants and developed under gnotobiotic conditions, to capture and host the rhizospheric microbiota. Afterward, it was tested by both a culture-independent (16S rRNA gene metabarcoding) and -dependent approach. Both methods revealed no significant differences between roots and adjacent clay chips in regard total abundance and structure of the present microbiota. Clay shaped as beads adequately supported the long-term preservation of viable pure isolates of typical rhizospheric microbes, i.e. Bacillus circulans, Klebsiella oxytoca, Sinorhizobium meliloti, and Saccharomyces sp., up to 11 months stored at −20°C, 4°C, and ambient temperature. The used clay chips and beads have the capacity to capture the root microbiota and to long-term preserve pure isolates. Hence, the developed approach is qualified to build on it a comprehensive strategy to transfer and store complex and living environmental microbiota of rhizosphere toward biotechnological application in sustainable plant production and environmental rehabilitation.

Background COVID-19 infection may cause severe respiratory distress and is associated with increased morbidity and mortality. Impaired cardiac function and/or pre-existing cardiovascular disease may be associated with poor prognosis. In the present study, we report a comprehensive cardiovascular characterization in the first consecutive collective of patients that was admitted and treated at the University Hospital of Tübingen, Germany. Methods 123 consecutive patients with COVID-19 were included. Routine blood sampling, transthoracic echocardiography and electrocardiography were performed at hospital admission. Results We found that impaired left-ventricular and right-ventricular function as well as tricuspid regurgitation > grade 1 were significantly associated with higher mortality. Furthermore, elevated levels of myocardial distress markers (troponin-I and NT pro-BNP) were associated with poor prognosis in this patient collective. Conclusion Impaired cardiac function is associated with poor prognosis in COVID-19 positive patients. Consequently, treatment of these patients should include careful guideline-conform cardiovascular evaluation and treatment. Thus, formation of a competent Cardio-COVID-19 team may represent a major clinical measure to optimize therapy of cardiovascular patients during this pandemic.

Besides glucosinolates, Brassica vegetables accumulate sulfur-containing (+)-S-methyl-l-cysteine sulfoxide (SMCSO, methiin), mainly known from Allium vegetables. Such (+)-S-alk(en)yl-l-cysteine sulfoxides can degrade to volatile organosulfur compounds (VOSCs), which have been linked to health beneficial effects. In the present study, the accumulation of SMCSO and the formation of VOSCs was investigated in Brassica oleracea vegetables. SMCSO content of commercially available white and red cabbages was monitored over a three-month period and linked with the formation of VOSCs. S-Methyl methanethiosulfinate was the main VOSC released from SMCSO. Upon heating, it degraded to dimethyltrisulfide and dimethyldisulfide, which were less abundant in fresh homogenates. SMCSO made up approximately 1% of the dry matter of cabbages and the overall contents were similar in white and red cabbages (3.2-10.2 and 3.9-10.3 µmol/g fresh weight, respectively). Using proteome profiling it was shown that recovery of VOSCs correlated with abundance of two isoforms of cystine lyase.

Salt stress tolerance of crop plants is a trait with increasing value for future food production. In an attempt to identify proteins that participate in the salt stress response of barley, we have used a cDNA library from salt-stressed seedling roots of the relatively salt-stress-tolerant cv. Morex for the transfection of a salt-stress-sensitive yeast strain (Saccharomyces cerevisiae YSH818 Δhog1 mutant). From the retrieved cDNA sequences conferring salt tolerance to the yeast mutant, eleven contained the coding sequence of a jacalin-related lectin (JRL) that shows homology to the previously identified JRL horcolin from barley coleoptiles that we therefore named the gene HvHorcH. The detection of HvHorcH protein in root extracellular fluid suggests a secretion under stress conditions. Furthermore, HvHorcH exhibited specificity towards mannose. Protein abundance of HvHorcH in roots of salt-sensitive or salt-tolerant barley cultivars were not trait-specific to salinity treatment, but protein levels increased in response to the treatment, particularly in the root tip. Expression of HvHorcH in Arabidopsis thaliana root tips increased salt tolerance. Hence, we conclude that this protein is involved in the adaptation of plants to salinity.

COVID-19 may lead to severe acute respiratory distress syndrome (ARDS) resulting in increased morbidity and mortality. Heart failure and/or pre-existing cardiovascular disease may correlate with poor outcomes and thus require special attention from treating physicians. The present study sought to investigate a possible impact of impaired myocardial function as well as myocardial distress markers on mortality or ARDS with need for mechanical ventilation in 157 consecutive patients with confirmed SARS-CoV-2 infection. All patients were admitted and treated at the University Hospital of Tübingen, Germany, during the first wave of the pandemic. Electrocardiography, echocardiography, and routine blood sampling were performed at hospital admission. Impaired left-ventricular and right-ventricular function, tricuspid regurgitation > grade 1, and elevated RV-pressure as well as thrombotic and myocardial distress markers (D-dimers, NT-pro-BNP, and troponin-I) were associated with mechanical ventilation and/or all-cause mortality. Impaired cardiac function is more frequent amidst ARDS, leading to subsequent need for mechanical ventilation, and thus denotes a poor outcome in COVID-19. Since a causal treatment for SARS-CoV-2 infection is still lacking, guideline-compliant cardiovascular evaluation and treatment remains the best approach to improve outcomes in COVID-19 patients with cardiovascular comorbidities.

The plasma membrane (PM) is at the interface of plant–pathogen interactions and, thus, many bacterial type-III effector (T3E) proteins target membrane-associated processes to interfere with immunity. The Pseudomonas syringae T3E HopZ1a is a host cell PM-localized effector protein that has several immunity-associated host targets but also activates effector-triggered immunity in resistant backgrounds. Although HopZ1a has been shown to interfere with early defense signaling at the PM, no dedicated PM-associated HopZ1a target protein has been identified until now. Here, we show that HopZ1a interacts with the PM-associated remorin protein NbREM4 from Nicotiana benthamiana in several independent assays. NbREM4 relocalizes to membrane nanodomains after treatment with the bacterial elicitor flg22 and transient overexpression of NbREM4 in N. benthamiana induces the expression of a subset of defense-related genes. We can further show that NbREM4 interacts with the immune-related receptor-like cytoplasmic kinase avrPphB-susceptible 1 (PBS1) and is phosphorylated by PBS1 on several residues in vitro. Thus, we conclude that NbREM4 is associated with early defense signaling at the PM. The possible relevance of the HopZ1a–NbREM4 interaction for HopZ1a virulence and avirulence functions is discussed. [Formula: see text]Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Comprehensive untargeted and targeted analysis of root exudate composition has advanced our understanding of rhizosphere processes. However, little is known about exudate spatial distribution and regulation. We studied the specific metabolite signatures of asparagus root exudates, root outer (epidermis and exodermis), and root inner tissues (cortex and vasculature). The greatest differences were found between exudates and root tissues. In total, 263 non-redundant metabolites were identified as significantly differentially abundant between the three root fractions, with the majority being enriched in the root exudate and/or outer tissue and annotated as ‘lipids and lipid-like molecules’ or ‘phenylpropanoids and polyketides’. Spatial distribution was verified for three selected compounds using MALDI-TOF mass spectrometry imaging. Tissue-specific proteome analysis related root tissue-specific metabolite distributions and rhizodeposition with underlying biosynthetic pathways and transport mechanisms. The proteomes of root outer and inner tissues were spatially very distinct, in agreement with the fundamental differences between their functions and structures. According to KEGG pathway analysis, the outer tissue proteome was characterized by a high abundance of proteins related to ‘lipid metabolism’, ‘biosynthesis of other secondary metabolites’ and ‘transport and catabolism’, reflecting its main functions of providing a hydrophobic barrier, secreting secondary metabolites, and mediating water and nutrient uptake. Proteins more abundant in the inner tissue related to ‘transcription’, ‘translation’ and ‘folding, sorting and degradation’, in accord with the high activity of cortical and vasculature cell layers in growth- and development-related processes. In summary, asparagus root fractions accumulate specific metabolites. This expands our knowledge of tissue-specific plant cell function.

Germplasm collections reflect the genetic variability in crops and their wild relatives. Hence, those genetic resources are tremendously valuable for breeders and researchers, especially in light of climatic change and stagnant crop production rates. In order to achieve improvements in crop production and end-use quality, favorable traits and donor alleles present in germplasm collections need to be identified and utilized. This review covers recent reports on the utilization of germplasm material to isolate genotypes of Brassica oleracea and B. rapa vegetables, focusing on high nutrient use efficiency, accumulation of biologically active metabolites, pest resistance, and favorable phenotypic appearance. We discuss the current state of Brassica vegetable collections in genebanks and summarize studies directed to the molecular characterization of those collections.

We profiled the grain oligosaccharide content of 154 two-row spring barley genotypes and quantified 27 compounds, mainly fructans, that exhibited differential abundance. Clustering revealed two major profile groups where the ‘high’ set contained greater amounts of sugar monomers, sucrose and overall fructans, but lower fructosylraffinose. GWAS identified a significant association for the variability of two fructan types; neoseries-DP7 and inulin-DP9 which showed increased strength when a compound-ratio GWAS was applied. Gene models within this region included five fructan biosynthesis genes, of which three (fructan:fructan 1-fructosyltransferase, sucrose:sucrose 1-fructosyltransferase, and sucrose:fructan 6-fructosyltransferase) have already been described. The remaining two, 6(G)-fructosyltransferase and vacuolar invertase1 have not previously been linked to fructan biosynthesis in barley and showed expression patterns distinct from those of the other three genes, including exclusive expression of 6(G)-fructosyltransferase in outer grain tissues at the storage phase. From exome capture data several SNPs related to inulin- and neoseries-type fructan variability were identified in fructan:fructan 1-fructosyltransferase and 6(G)-fructosyltransferase genes Co-expression analyses uncovered potential regulators of fructan biosynthesis including transcription factors. Our results provide evidence for the distinct biosynthesis of neoseries-type fructans during barley grain maturation plus new gene candidates likely involved in the differential biosynthesis of the various fructan types.HighlightGrain fructan profiles in barley are more complex than previously expected and variations in a diversity panel relate to a genomic region where fructan biosynthesis genes cluster.

Soil-borne pathogens can have considerable detrimental effects on asparagus (Asparagus officinalis) growth and production, notably caused by the Fusarium species F. oxysporum f.sp. asparagi, F. proliferatum and F. redolens. In this study, their species-specific impact regarding disease severity and root morphological traits was analysed. Additionally, various isolates were characterised based on in vitro physiological activities and on protein extracts using matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS). The response of two asparagus cultivars to the different Fusarium species was evaluated by inoculating experiments. Differences in aggressiveness were observed between Fusarium species and their isolates on roots, while no clear disease symptoms became visible in ferns eight weeks after inoculation. F. redolens isolates Fred1 and Fred2 were the most aggressive strains followed by the moderate aggressive F. proliferatum and the less and almost non-aggressive F. oxysporum isolates, based on the severity of disease symptoms. Fungal DNA in stem bases and a significant induction of pathogenesis-related gene expression was detectable in both asparagus cultivars. A significant negative impact of the pathogens on the root characteristics total root length, volume, and surface area was detected for each isolate tested, with Fred1 causing the strongest effects. No significant differences between the tested asparagus cultivars were observed.

High-throughput cultivation methods have recently been developed to accelerate the recovery of microorganisms reluctant to cultivation. They simulate in situ environmental conditions for the isolation of environmental microbiota through the exchange of growth substrates during cultivation. Here, we introduce leaf-based culture media adopting the concept of the plant being the master architect of the composition of its microbial community. Pre-physical treatments of sunflower plant leaves, namely punching, freezing, and/or autoclavation, allowed the diffusion of electrolytes and other nutrients to configure the leaf surface as a natural pad, i.e., creating an “in situ similis” environment suitable for the growth of rarely isolated microbiota. We used surface inoculation and membrane-filtration methods to assess the culturability of endophytic bacteria from the sunflower phyllosphere and rhizosphere. Both methods supported excellent colony-forming unit (CFU) development when compared to standard R2A medium, with a special affinity to support better growth of epiphytic and endophytic populations of the phyllosphere compared with the rhizosphere. A 16S rRNA gene analysis of >122 representative isolates indicated the cultivation of a diverse set of microorganisms by application of the new methods. It indicated the predominance of 13 genera of >30 potential species, belonging to Firmicutes, Proteobacteria, and Actinobacteria, and especially genera not commonly reported for sunflower, e.g., Rhizobium, Aureimonas, Sphingomonas, Paracoccus, Stenotrophomonas, Pantoea, Kosakonia, and Erwinia. The strategy successfully extended diversity and richness in the endophyllosphere compared to the endorhizosphere, while CFUs grown on the standard R2A medium mainly pertain to Firmicutes, especially Bacillus spp. MALDI-TOF MS analysis clustered the isolates according to their niche and potential functions, where the majority of isolates of the endorhizosphere were clustered away from those of the endophyllosphere. Isolates identified as Gammaproteobacteria and Alphaproteobacteria were distinguishably sub-clustered, which was in contrast to the heterogeneous isolates of Firmicutes (Bacillus spp.). In conclusion, leaf in situ similis cultivation is an effective strategy to support the future application of culturomics of plant microbiota. This is an effort to access novel isolates that are more adapted and competitive in their natural environments, especially those subjected to abiotic stresses like those prevailing in arid/semi-arid zones, and, consequently, to support the application of agro-biotechnologies, among other technologies, to improving agriculture in such zones.

Glucosinolates present in

Glucosinolates present in Brassicaceae play a major role in herbivory defense. Upon tissue disruption, glucosinolates come into contact with myrosinase, which initiates their breakdown to biologically active compounds. Among these, the formation of epithionitriles is triggered by the presence of epithiospecifier protein (ESP) and a terminal double bond in the glucosinolate side chain. One ESP gene is characterized in the model plant Arabidopsis thaliana (AtESP; At1g54040.2). However, Brassica species underwent genome triplication since their divergence from the Arabidopsis lineage. This indicates the presence of multiple ESP isoforms in Brassica crops that are currently poorly characterized. We identified three B. oleracea ESPs, specifically BoESP1 (LOC106296341), BoESP2 (LOC106306810), and BoESP3 (LOC106325105) based on in silico genome analysis. Transcript and protein abundance were assessed in shoots and roots of four B. oleracea vegetables, namely broccoli, kohlrabi, white, and red cabbage, because these genotypes showed a differential pattern for the formation of glucosinolate hydrolysis products as well for their ESP activity. BoESP1 and BoESP2 were expressed mainly in shoots, while BoESP3 was abundant in roots. Biochemical characterization of heterologous expressed BoESP isoforms revealed different substrate specificities towards seven glucosinolates: all isoforms showed epithiospecifier activity on alkenyl glucosinolates, but not on non-alkenyl glucosinolates. The pH-value differently affected BoESP activity: while BoESP1 and BoESP2 activities were optimal at pH 6-7, BoESP3 activity remained relatively stable from pH 4 to 7. In order test their potential for the in vivo modification of glucosinolate breakdown, the three isoforms were expressed in A. thaliana Hi-0, which lacks AtESP expression, and analyzed for the effect on their respective hydrolysis products. The BoESPs altered the hydrolysis of allyl glucosinolate in the A. thaliana transformants to release 1-cyano-2,3-epithiopropane and reduced formation of the corresponding 3-butenenitrile and allyl isothiocyanate. Plants expressing BoESP2 showed the highest percentage of released epithionitriles. Given these results, we propose a model for isoform-specific roles of B. oleracea ESPs in glucosinolate breakdown.

Although the physiological consequences of plant growth under saline conditions have been well described, understanding the core mechanisms conferring plant salt adaptation has only started. We target the root plasma membrane proteomes of two barley varieties, cvs. Steptoe and Morex, with contrasting salinity tolerance. In total, 588 plasma membrane proteins were identified by mass spectrometry, of which 182 were either cultivar or salinity stress responsive. Three candidate proteins with increased abundance in the tolerant cv. Morex were involved either in sterol binding (a GTPase-activating protein for the adenosine diphosphate ribosylation factor [ZIGA2], and a membrane steroid binding protein [MSBP]) or in phospholipid synthesis (phosphoethanolamine methyltransferase [PEAMT]). Overexpression of barley MSBP conferred salinity tolerance to yeast cells, whereas the knock-out of the heterologous AtMSBP1 increased salt sensitivity in Arabidopsis. Atmsbp1 plants showed a reduced number of lateral roots under salinity, and root-tip-specific expression of barley MSBP in Atmsbp1 complemented this phenotype. In barley, an increased abundance of MSBP correlates with reduced root length and lateral root formation as well as increased levels of auxin under salinity being stronger in the tolerant cv. Morex. Hence, we concluded the involvement of MSBP in phytohormone-directed adaptation of root architecture in response to salinity.

Plant growth-promoting bacteria (PGPB) affect host physiological processes in various ways. This study aims at elucidating the dependence of bacterial-induced growth promotion on the plant genotype and characterizing plant metabolic adaptations to PGPB. Eighteen Arabidopsis thaliana accessions were inoculated with the PGPB strain Kosakonia radicincitans DSM 16656(T). Colonisation pattern was assessed by enhanced green fluorescent protein (eGFP)-tagged K. radicincitans in three A. thaliana accessions differing in their growth response. Metabolic impact of bacterial colonisation was determined for the best responding accession by profiling distinct classes of plant secondary metabolites and root exudates. Inoculation of 18 A. thaliana accessions resulted in a wide range of growth responses, from repression to enhancement. Testing the bacterial colonisation of three accessions did not reveal a differential pattern. Profiling of plant secondary metabolites showed a differential accumulation of glucosinolates, phenylpropanoids and carotenoids in roots. Analysis of root exudates demonstrated that primary and secondary metabolites were predominantly differentially depleted by bacterial inoculation. The plant genotype controls the bacterial growth promoting traits. Levels of lutein and beta-carotene were elevated in inoculated roots. Supplementing a bacterial suspension with beta-carotene increased bacterial growth, while this was not the case when lutein was applied, indicating that beta-carotene could be a positive regulator of plant growth promotion.

The plant phyllosphere is colonized by a complex ecosystem of microorganisms. Leaves of raw eaten vegetables and herbs are habitats for bacteria important not only to the host plant, but also to human health when ingested via meals. The aim of the current study was to determine the presence of putative probiotic bacteria in the phyllosphere of raw eaten produce. Quantification of bifidobacteria showed that leaves of Lepidium sativum L., Cichorium endivia L., and Thymus vulgaris L. harbor between 103 and 106 DNA copies per gram fresh weight. Total cultivable bacteria in the phyllosphere of those three plant species ranged from 105 to 108 CFU per gram fresh weight. Specific enrichment of probiotic lactic acid bacteria from C. endivia, T. vulgaris, Trigonella foenum-graecum L., Coriandrum sativum L., and Petroselinum crispum L. led to the isolation of 155 bacterial strains, which were identified as Pediococcus pentosaceus, Enterococcus faecium, and Bacillus species, based on their intact protein pattern. A comprehensive community analysis of the L. sativum leaves by PhyloChip hybridization revealed the presence of genera Bifidobacterium, Lactobacillus, and Streptococcus. Our results demonstrate that the phyllosphere of raw eaten produce has to be considered as a substantial source of probiotic bacteria and point to the development of vegetables and herbs with added probiotic value.

The plasma membrane (PM) is at the interface of plant-pathogen interactions and, thus, many bacterial type-III effector (T3E) proteins target membrane-associated processes to interfere with immunity. The

Plant microbiota support the diversity and productivity of plants. Thus, cultivation-dependent approaches are indispensable for in vitro manipulation of hub taxa. Despite recent advances in high-throughput methods, cultivability is lagging behind other environmental microbiomes, notably the human microbiome. As a plant-based culturing strategy, we developed culture media based on a broth of cooked aqueous mixtures of host plants. This improved the in vitro growth of representative isolates of plant microbiota and extended the in situ recovery of plant microbiota. With clover, 16S rRNA gene sequencing of representative isolates confirmed the predominance of Firmicutes, Alphaproteobacteria and Gammaproteobacteria, and less frequently Bacteroidetes and Actinobacteria. Whereas bovine-based culture media (modified R2A) confined the diversity to Firmicutes, the plant broth-based culture media revealed a wider scope of endophytes beyond rhizobia, i.e., multiple genera such as Chryseobacterium, Cronobacter, Kosakonia, Tsukamurella, and a potentially/presumptive novel species. Matrix-assisted laser desorption/ionization time-of-flight (MADI-TOF) analysis clustered isolates according to their plant niches, the endo-phyllosphere/endo-rhizosphere. We recommend the plant broth for simplicity, reproducibility and perdurable storage, supporting future culturomics applications, good laboratory practice (GLP) and good manufacturing practice (GMP). The strategy creates an &ldquo, in-situ-similis&rdquo, vegan nutritional matrix to analyze microbial diversity and reveal novel microbial resources pertinent to biotechnological and environmental applications.

The plasma membrane is at the interface of plant-pathogen interactions and thus many bacterial type-III effector proteins (T3Es) target membrane-associated processes to interfere with immunity. The Pseudomonas syringae T3E is a host cell plasma membrane (PM)-localized effector protein that has several immunity associated host targets but also activates effector triggered immunity (ETI) in resistant backgrounds. Although HopZ1a has been shown to interfere with early defense signaling at the PM, no dedicated plasma membrane-associated HopZ1a target protein has been identified until now. We show here, that HopZ1a interacts with the PM-associated remorin protein NbREM4 from Nicotiana benthamiana in several independent assays. NbREM4 re-localizes to membrane sub-domains after treatment with the bacterial elicitor flg22 and transient overexpression of NbREM4 in N. benthamiana induces the expression of a subset of defense related genes. We can further show that NbREM4 interacts with the immune-related receptor-like cytoplasmic kinase PBS1 and is phosphorylated by PBS1 on several residues in vitro. Thus, we conclude that NbREM4 is associated with early defense signaling at the PM. The possible relevance of the HopZ1a/NbREM4 interaction for HopZ1a virulence and avirulence functions is discussed.

An in-depth glucosinolate (GLS) profiling was performed on a core collection of 91 Brassica rapa accessions, representing diverse morphotypes of heterogeneous geographical origin, to better understand the natural variation in GLS accumulation and GLS breakdown product formation. Leaves of the 91 B. rapa accessions were analyzed for their GLS composition by UHPLC-DAD and the corresponding breakdown products by GC-MS. Fifteen different GLSs were identified, and aliphatic GLSs prevailed regarding diversity and concentration. Twenty-three GLS breakdown products were identified, among them nine isothiocyanates, ten nitriles, and four epithionitriles. Epithionitriles were the prevailing breakdown products due to the high abundance of alkenyl GLSs. The large scale data set allowed the identification of correlations in abundance of specific GLSs or of GLS breakdown products. Discriminant function analysis identified subspecies with high levels of similarity in the acquired metabolite profiles. In general, the five main subspecies grouped significantly in terms of their GLS profiles.

Plants of the order Brassicales produce glucosinolates (GS), a group of secondary metabolites that are part of an elaborate defense system. But it is not the GS itself rather its enzymatic hydrolysis products that cause the bioactive effects protecting the plants against pests and pathogens. Thus the enzymatic hydrolysis and a variety of additional influential factors determine the structural outcome of the GS degradation process. To evaluate the possible diversity of defense metabolites a range of 19 Arabidopsis thaliana accessions were selected showing divergence in their geographical origin, in their phenotype, and in their GS profile. These particular accessions accumulate several alkenyl GS, hydroxyalkyl GS, methylthioalkyl GS, and methylsulfinylalkyl GS in their rosette leaves whereas the indole GS contents are relatively invariant, as analyzed by UHPLC-DAD. After tissue disruption the enzymatic formation of GS hydrolysis products was examined and breakdown products were identified and quantified by GC-MS. Great differences in the amount and structure of volatile enzymatic degradation products could be observed in the different accessions, with strong variation in formation of epithionitriles, nitriles, and isothiocyanates. The occurrence of specific GS hydrolysis products was put in relation to relative gene expression profiles of myrosinases and specifier proteins as measured by RT-qPCR, and in relation to relative protein abundance of epithiospecifier protein. Dependent on the different GS profiles and reliant on degradation protein abundance and composition the ecotypes strongly varied in their ability to form isothiocyanates, nitriles and epithionitriles, thus increasing the plants' equipment of defense metabolites.