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Proposed aliphatic GLS pathway regulatory model. A, Aliphatic GLS biosynthetic pathway with structures and enzymes. Enzymes in black are ones with promoters included in this study. Those in gray were not cloned. The use of n indicates the number of carbons introduced to the side chain from the elongation cycle and can vary from 1 to 7. The promoters are color coded based on their pathway membership as follows: indolic GLSs are pink, aliphatic regulatory genes are purple, and aliphatic peripheral genes are red. The aliphatic biosynthetic genes are parsed into the core pathway (green), elongation (blue), modifying (yellow), and seed specific (orange) to visualize regulation along the linear model of the pathway. B, A proposed model of aliphatic GLS pathway regulation. In this model, the pathway is regulated by the JA pathway via the bHLH’s MYC2/ MYC3/MYC4 interacting with the MYB28/MYB29/MYB76 proteins and binding the respective promoters. C, Transcriptional analysis of the aliphatic GLS pathway in mutants missing the MYB28 and MYB29 TFs (blue) or MYC2/MYC3/MYC4 TFs (red). The value is shown as the relative value of the transcript in the mutant with the wild type set to 1 for each gene. The genes are ordered by their position in the biosynthetic pathway. The transcriptional data presented are from previous publications with full statistical analysis (Sonderby et al., 2010b; Schweizer et al., 2013). WT, Wild type JA-ILE, isoleucyl jasmonic acid; JAZ, jasmonate ZIM domain proteins; Coi1, Coronatine Insensitive1; BCAT4, BRANCHCHAIN AMINOTRANSFERASE4; BAT5, BILE ACID TRANSPORTER5; IMD3, ISOPROPYL MALATE DEHYDROGENASE3; MAM1, METHYLIOALKYLMALATE SYNTHASE1; IPMI1, ISOPROPYL MALATE ISOMERASE1; CYP, CYTOCHROME P450; GGP1, GAMMA GLUTAMYL PEPTIDASE1; GSOH, GLUCOSINOLATE HYDROXYLATION; GSOX1-5, GLUCOSINOLATE OXIDASE1-5; GSTF11, GLUTHATHIONE- S -TRANSFERASE11; CSLyase, CYSTEINE-S-CONJUGATE b -LYASE; UGT, UDP-GLYCOSYLTRANSFERASE; SOT, SULFUR TRANSFERASE; AOP3, ALKENYLHYDROXYPROPYL3; BZO1, BENZOYLOXY1.
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: A key unanswered question in plant biology is how a plant regulates metabolism to maximize performance across an array of biotic and abiotic environmental stresses. In this study, we addressed the potential breadth of transcriptional regulation that can alter accumulation of the defensive glucosinolate metabolites in Arabidopsis. A systematic yea...
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... (Gaudinier et al., 2011). This analysis found a large number of newly identi fi ed potential TFs that could interact with the biosynthetic genes and/or the known regulatory TFs. Among these TFs were ones known to be involved with growth, biotic, and abiotic signaling. Over 75% of the tested mutant TFs found by Y1H altered the accumulation of the aliphatic GLSs similarly to single mutants in the known MYBs/MYCs (Beekwilder et al., 2008; Sønderby et al., 2010b; Schweizer et al., 2013). The phenotypic effects of the TF mutants were highly dependent upon the environment and tissue in which the accumulation was measured. This shows the importance of performing a gene-centered approach coupled with a nonbiased set of TFs to elucidate conditional-dependent regulatory TFs (Arda and Walhout, 2010). We could show that TFs that bound similar aliphatic GLS promoters also had similar phenotypic consequences using a nonlinear matrix analysis. This suggests that, at least for the aliphatic GLSs, the pathway appears to be regulated as a set of overlapping modules. These overlapping modules allow for the integration of multiple signals at the promoter level within the pathway. Future research will be needed to develop a cohesive model involving the dozens of newly identi fi ed TFs and the previously known TFs ( Fig. 1). To develop a detailed graph of the potential transcriptional regulatory network mediating the expression of aliphatic GLS genes, we cloned approximately 2 kb upstream or to the nearest gene if this was less than 2 kb for the 22 known enzyme-encoding genes for this pathway (Figs. 1A and 2; Supplemental Table S1; Sønderby et al., 2010a; Gaudinier et al., 2011). These genes include all of the known genes for the pathway except for two genes ( GGP and CYP79F2 ; Fig. 1A; Geu-Flores et al., 2009; Sønderby et al., 2010a). We also cloned the promoters from the known MYB regulatory factors (MYB28 and MYB29) that are critical for the aliphatic GLS pathway (Fig. 1B; Supplemental Table S1; Sønderby et al., 2007, 2010a, 2010b). In addition, we also included the promoter of MYB76, which is a homolog of MYB28 and MYB29 and also controls aliphatic GLS accumulations (Sønderby et al., 2007, 2010a, 2010b). As a comparison, we also included the promoters from six genes that had been peripherally associated with the GLS pathway either by being shared with the Val biosynthetic pathway or coexpressing with the pathway (IMD3, IPMI2, IPMI1, and PMSR1 – PMSR3). Another comparison was provided by including two promoters from the indolic GLS pathway, which is largely discrete from the aliphatic biosynthetic pathway (UGT74B and GSTF9 ; Sønderby et al., 2010b). Using the sequences of the cloned promoters, we queried the TF binding sites that may be enriched within these promoters using the Athena analysis suite (O ’ Connor et al., 2005). This showed that the aliphatic GLS promoters are enriched in binding sites for the two classes of TFs previously associated with regulating this pathway, the MYBs and basic helix-loop-helix (bHLH) MYCs (Fig. 2; Supplemental Table S2; Gigolashvili et al., 2007a, 2007b, 2008; Hirai et al., 2007; Sønderby et al., 2007, 2010a, 2010b; Schweizer et al., 2013). There was also a strong enrichment in Basic Leucine Zipper Domain (bZIP) and Homeodomain DNA binding elements and a weaker enrichment in binding elements for the MADs, Auxin Response Factor (ARF), and Apetala2 (AP2)/Ethyl- ene-response factor (ERF) TF families (Supplemental Table S2). The Homeodomain, bZIP, MADS, ARFs, and AP2/ERF TF families have not been previously associated with regulating the aliphatic GLS pathway, suggesting that there are potentially a number of un- known TFs that regulate this pathway. We then assessed the interaction of each promoter with all 659 TFs of the published stele-expressed TF collection (Fig. 2; Gaudinier et al., 2011). The stele is the predominant tissue in which the aliphatic GLS biosynthetic pathway genes are expressed (Sønderby et al., 2010a; Moussaieff et al., 2013). We also added the MYB28, MYB29, and MYB76 TFs to this collection because they bind the majority of tested GLS promoters in Arabidopsis cell culture assays (Gigolashvili et al., 2007a, 2007b, 2008). The entire Y1H analysis identi fi ed 487 promoter/TF interactions between 140 TFs and the 21 aliphatic biosynthetic gene promoters (Supplemental Table S3). On average, each promoter interacted with 23.3 6 2.6 TFs (average 6 SE ). By contrast, the majority of TFs interacted with only one or two promoters (Figs. 2 and 3A). To determine an empirical threshold for identifying TFs that likely interact with the aliphatic GLS pathway, we tested the interaction of MYB28, MYB29, and MYB76 with all of the aliphatic GLS pathway promoters in the Y1H system. MYB28, MYB29, and MYB76 have been experimentally validated to bind at least six of the aliphatic GLS pathway promoters using an Arabidopsis tissue culture system (Gigolashvili et al., 2007a, 2007b, 2008). Using our Y1H system, we identi fi ed three, zero, and two interactions, respectively, between these TFs and aliphatic GLS biosynthetic promoters. Differ- ences in interaction numbers in tissue cultures compared with Y1H are likely due to false positives and false negatives associated with each system (Yu et al., 2008; Walhout, 2011). These results using known interacting TFs provide us an ability to develop an empirical threshold for calling TFs that likely interact with the pathway. Thus, as a compromise between false positives and false negatives, we decided to use three interactions as an empirically validated threshold to identify TFs that are likely to be biologically relevant. This threshold requires these TFs to have at least as many interactions as the validated MYB28 TF. Using this threshold, we are likely removing some biologically relevant promoter-TF interactions because the MYB76 TF, which does regulate the pathway but is not a critical regulator of the pathway, had only two interactions and would have been dropped from our analysis. Of the 144 TFs identi fi ed in the Y1H analysis, 52 interacted with three or more of the aliphatic biosynthetic gene promoters similar to the validated MYB28, suggesting that we have identi fi ed a large collection of TFs potentially regulating aliphatic ...
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... Considering the important and diverse functions of indolic glucosinolates, we explored the transcriptional regulation of their biosynthesis in cabbage by screening and validating the upstream regulators of BolCYP83B1 for the following reasons: (1) BolCYP83B1 catalyzes the key step in the core structure formation of the biosynthesis of indolic glucosinolates [18,19]; (2) CYP83B1 is the gene with one of the largest numbers of upstream candidate regulators in the model plant Arabidopsis according to our previous study [20][21][22]; and (3) the expression level of BolCYP83B1 has profound influences on the accumulation of the key plant hormone auxin, therefore modulating plant development [23], which gives us the opportunity to study how plants coordinate defense and development. The objectives of this study were to identify and functionally validate the BolCYP83B1 of cabbage, screen its upstream regulators, and functionally validate one of its top candidate regulators, BolANT3, in cabbage overexpression lines and virus-induced gene silencing (VIGS) lines. ...
... As the key biosynthetic enzyme converting indole-3-acetaldoxime (IAOx) into the following core structural formation steps of the indolic glucosinolate pathway, CYP83B1 not only plays an important role in the biosynthesis of indolic glucosinolates but also modulates the accumulation of camalexin and the key plant hormone auxin, all of which are downstream metabolic products of IAOx [18,23,24]. Therefore, CYP83B1 was selected as one of several important control genes in our efforts over the past 15 years to explore the transcriptional regulation of the aliphatic glucosinolate pathway using an enhanced yeast one-hybrid assay [20][21][22]. In these studies, we identified 253 transcription factors (TFs) that bind to the promoter of CYP83B1 in Arabidopsis (Supplementary Table S1), and interestingly, the numbers of upstream regulators of CYP83B1 in our screening are some of the highest among all of the tested promoters [22]. ...
... modulates the accumulation of camalexin and the key plant hormone auxin, all of which are downstream metabolic products of IAOx [18,23,24]. Therefore, CYP83B1 was selected as one of several important control genes in our efforts over the past 15 years to explore the transcriptional regulation of the aliphatic glucosinolate pathway using an enhanced yeast one-hybrid assay [20][21][22]. In these studies, we identified 253 transcription factors (TFs) that bind to the promoter of CYP83B1 in Arabidopsis (Supplementary Table S1), and interestingly, the numbers of upstream regulators of CYP83B1 in our screening are some of the highest among all of the tested promoters [22]. ...
Indolic glucosinolates are a group of plant secondary metabolites found in Brassica vegetables, and their breakdown products could act as important anti-cancer and defense compounds against biotic stresses. Transcriptional regulation plays a key role in modulating the biosynthesis of indolic glucosinolates in the model plant Arabidopsis, but little is known about the transcriptional regulatory landscape of these glucosinolates in Brassica vegetables. In this study, we selected and functionally validated the important biosynthetic gene BolCYP83B1 from the indolic glucosinolate pathway in cabbage. Through a yeast one-hybrid assay, we systemically screened and identified upstream regulators of BolCYP83B1 in cabbage with BolANTs as the top candidates for further functional validation. Two homologs of BolANTs, BolANT1 and BolANT3, were confirmed to bind the promoter of BolCYP83B1 via both a yeast one-hybrid assay and an LUC assay. The overexpression of BolANT3 in cabbage significantly increased the accumulation of indolic glucosinolates, while the virus-induced gene silencing (VIGS) of BolANT3 significantly reduced the accumulation of indolic glucosinolates in cabbage. Our work provides valuable insights into the transcriptional regulatory mechanisms of indolic glucosinolates in Brassica vegetables.
... Multiple key transcription factors (TFs) have been identified and shown to turn on/off specific pathways, including MYB28 and MYB29 for the aliphatic glucosinolate pathway (Gigolashvili et al. 2007;Hirai et al. 2007;Sønderby et al. 2007), MYB51, MYB34 and MYB122 for the indolic glucosinolate pathway (Frerigmann and Gigolashvili 2014), and MYC2, MYC3 and MYC4 for both aliphatic and indolic glucosinolate pathways (Schweizer et al. 2013). We have systematically explored the transcriptional regulation of aliphatic glucosinolate pathways over the past 15 years through the enhanced yeast one-hybrid (Y1H) assay in Arabidopsis (Gaudinier et al. 2011), and have identified large numbers of novel regulators from diverse TF families (Li et al. 2014;Tang et al. 2021;Chen et al. 2024). By using these TFs to construct unique and hypothesis-driven networks, we successfully identified large numbers of epistatic interactions controlling glucosinolate accumulation and plant development (Li et al. 2018(Li et al. , 2020. ...
... We previously identified novel regulators in aliphatic glucosinolate pathways, and most of these regulators could modulate the accumulation of both aliphatic and indolic glucosinolates. These TFs also participate in many other key biological processes, for example, ANT controlling cell proliferation (Elliott et al. 1996;Klucher et al. 1996) and ILR3 maintaining intracellular iron ion homeostasis (Rampey et al. 2006), as well as TFs in abscisic acid signalling pathway, ethylene signalling pathway, cuticular wax biosynthesis, pollen tube growth, the synthesis of seed mucilage polysaccharides, blue light signalling and responses to freezing and low oxygen stress (Li et al. 2014). By using the above A. alternata infection assay, we explored the potential novel regulators through a collection of Agrobacterium transfer DNA (T-DNA) insertion lines of these 20 TFs (Tables S1-S3). ...
... As our collections of the TFs were screened and validated as regulators of the glucosinolate biosynthetic pathway (Li et al. 2014), we then systematically measured and tested the glucosinolate phenotypes of the 20 TF mutants lines together with wild-type Col-0 after A. alternata infection (Tables S7-S9). Among all the eight glucosinolates that we could detect and accurately measure in the Col-0 background, 4MOI3M was the only glucosinolate whose content was significantly altered after A. alternata infection in all analysis of variance (ANOVA) tests (p < 0.001, Table S7, the 'infect' term of the ANOVA model). ...
Necrotrophic pathogens cause serious threats to agricultural crops, and understanding the resistance genes and their genetic networks is key to breeding new plant cultivars with better resistance traits. Although Alternaria alternata causes black spot in important leafy brassica vegetables, and leads to significant loss of yield and food quality, little is known about plant–A. alternata interactions. In this study, we used a unique and large collection of single, double and triple mutant lines of defence metabolite regulators in Arabidopsis to explore how these transcription factors and their epistatic networks may influence A. alternata infections. This identified nine novel regulators and 20 pairs of epistatic interactions that modulate Arabidopsis plants' defence responses to A. alternata infection. We further showed that the glucosinolate 4‐methoxy‐indol‐3‐ylmethyl is the only glucosinolate consistently responsive to A. alternata infection in Col‐0 ecotype. With the further exploration of the regulators and the genetic networks on modulating the accumulation of glucosinolates under A. alternata infection, an inverted triangle regulatory model was proposed for Arabidopsis plants' defence responses at a metabolic level and a phenotypic level.
... We successfully identified and validated dozens of novel regulators of biosynthetic genes in the aliphatic glucosinolate pathway in the model plant Arabidopsis [13,[30][31][32][33]. In this current study, we further explored the upstream regulators of BoMYB28s in the aliphatic glucosinolates pathway in cabbage, not only since cabbage is a staple vegetable around the world but also since rich genomic resources and research database information exists for this type of plant [34,35]. ...
... We have explored the transcriptional regulation of the aliphatic glucosinolates pathway and successfully identified dozens of new transcriptional regulators of this pathway in the model plant Arabidopsis [30,31]. Although most of the promoters in our yeast onehybrid screening assay were cloned from biosynthetic genes in the aliphatic glucosinolate pathway, we also cloned the promoters of the core regulators of the aliphatic glucosinolate pathway, MYB28 and MYB29, and screened upstream regulators of MYB28 and MYB29 [13,30]. ...
... We have explored the transcriptional regulation of the aliphatic glucosinolates pathway and successfully identified dozens of new transcriptional regulators of this pathway in the model plant Arabidopsis [30,31]. Although most of the promoters in our yeast onehybrid screening assay were cloned from biosynthetic genes in the aliphatic glucosinolate pathway, we also cloned the promoters of the core regulators of the aliphatic glucosinolate pathway, MYB28 and MYB29, and screened upstream regulators of MYB28 and MYB29 [13,30]. In total, 2116 interactions were identified, with 364 unique transcription factors binding the promoters of MYB28 and MYB29 (Table S1). ...
Aliphatic glucosinolates are an abundant group of plant secondary metabolites in Brassica vegetables, with some of their degradation products demonstrating significant anti-cancer effects. The transcription factors MYB28 and MYB29 play key roles in the transcriptional regulation of aliphatic glucosinolates biosynthesis, but little is known about whether BoMYB28 and BoMYB29 are also modulated by upstream regulators or how, nor their gene regulatory networks. In this study, we first explored the hierarchical transcriptional regulatory networks of MYB28 and MYB29 in a model plant, then systemically screened the regulators of the three BoMYB28 homologs in cabbage using a yeast one-hybrid. Furthermore, we selected a novel RNA binding protein, BoRHON1, to functionally validate its roles in modulating aliphatic glucosinolates biosynthesis. Importantly, BoRHON1 induced the accumulation of all detectable aliphatic and indolic glucosinolates, and the net photosynthetic rates of BoRHON1 overexpression lines were significantly increased. Interestingly, the growth and biomass of these overexpression lines of BoRHON1 remained the same as those of the control plants. BoRHON1 was shown to be a novel, potent, positive regulator of glucosinolates biosynthesis, as well as a novel regulator of normal plant growth and development, while significantly increasing plants’ defense costs.
... Moreover, MYB transcription factors, specifically MYB28, MYB29, MYB34, and MYB122, play a pivotal role in elevating the expression of genes within the glucosinolate biosynthetic pathway, contributing to enhanced glucosinolate accumulation (Guo et al., 2013). The MYB/MYC model, involving MYB28, MYB29, MYC2, MYC3, and MYC4, influences aliphatic GS accumulation (Li et al., 2014). MYC2, a transcriptional activator in the MYC2-branch of the JA pathway, contributes to the wound-response and defense against insect herbivores (Verhage et al., 2011). ...
Plants have evolved distinct defense strategies in response to a diverse range of chewing and sucking insect herbivory. While chewing insect herbivores, exemplified by caterpillars and beetles, cause visible tissue damage and induce jasmonic acid (JA)-mediated defense responses, sucking insects, such as aphids and whiteflies, delicately tap into the phloem sap and elicit salicylic acid (SA)-mediated defense responses. This review aims to highlight the specificity of defense strategies in Brassica plants and associated underlying molecular mechanisms when challenged by herbivorous insects from different feeding guilds (i.e., chewing and sucking insects). To establish such an understanding in Brassica plants, the typical defense responses were categorized into physical, chemical, and metabolic adjustments. Further, the impact of contrasting feeding patterns on Brassica is discussed in context to unique biochemical and molecular modus operandi that governs the resistance against chewing and sucking insect pests. Grasping these interactions is crucial to developing innovative and targeted pest management approaches to ensure ecosystem sustainability and Brassica productivity.
... 56,94,95 The GSL pathway is activated during immune signaling and has been implicated in resistance against a variety of fungal and oomycete pathogens. 56,96 Consistent with these previous findings, we observed an overall induction of genes involved in GSL biosynthesis in cells that had direct contact with C. higginsianum. Importantly, different genes were specifically induced in different cell types. ...
... The other callus-expressed WRKY TF, WRKY45, was mainly studied with respect to its role in leaf senescence and defense responses [141][142][143][144]. However, it was also found to be part of the transcriptional network controlling vascular development in Arabidopsis [145]. ...
In response to different degrees of mechanical injury, certain plant cells re-enter the division cycle to provide cells for tissue replenishment, tissue rejoining, de novo organ formation, and/or wound healing. The intermediate tissue formed by the dividing cells is called a callus. Callus formation can also be induced artificially in vitro by wounding and/or hormone (auxin and cytokinin) treatments. The callus tissue can be maintained in culture, providing starting material for de novo organ or embryo regeneration and thus serving as the basis for many plant biotechnology applications. Due to the biotechnological importance of callus cultures and the scientific interest in the developmental flexibility of somatic plant cells, the initial molecular steps of callus formation have been studied in detail. It was revealed that callus initiation can follow various ways, depending on the organ from which it develops and the inducer, but they converge on a seemingly identical tissue. It is not known, however, if callus is indeed a special tissue with a defined gene expression signature, whether it is a malformed meristem, or a mass of so-called “undifferentiated” cells, as is mostly believed. In this paper, I review the various mechanisms of plant regeneration that may converge on callus initiation. I discuss the role of plant hormones in the detour of callus formation from normal development. Finally, I compare various Arabidopsis gene expression datasets obtained a few days, two weeks, or several years after callus induction and identify 21 genes, including genes of key transcription factors controlling cell division and differentiation in meristematic regions, which were upregulated in all investigated callus samples. I summarize the information available on all 21 genes that point to the pre-meristematic nature of callus tissues underlying their wide regeneration potential.
... GSLs undergo hydrolysis reactions under their degradation enzyme, myrosinase, to produce products such as isothiocyanates, thiocyanates, and acetonitrile . The afore-mentioned products are involved in anti-cancer and anti-bacterial (Augustine and Bisht, 2015;Soundararajan and Kim, 2018) processes, resistance to herbivore feeding, pathogenic microbial infestation (Clay et al., 2009;Li et al., 2014;, and the formation of specific flavors in cruciferous vegetables (Engel et al., 2006). The biosynthetic precursors of GSLs include amino acids such as methionine, tryptophan, phenylalanine, and leucine. ...
The major enzyme encoded by the glucosinolate biosynthetic gene AOP2 is involved in catalyzing the conversion of glucoiberin (GIB) into sinigrin (SIN) in Brassicaceae crops. The AOP2 proteins have previously been identified in several Brassicaceae species, but not in Tumorous stem mustard. As per this research, the five identified members of the AOP2 family from the whole genome of Brassica juncea named BjuAOP2.1-BjuAOP2.5 were found to be evenly distributed on five chromosomes. The subcellular localization results implied that BjuAOP2 proteins were mainly concentrated in the cytoplasm. Phylogenetic analysis of the AOP2 proteins from the sequenced Brassicaceae species in BRAD showed that BjuAOP2 genes were more closely linked to Brassica carinata and Brassica rapa than Arabidopsis. In comparison with other Brassicaceae plants, the BjuAOP2 members were conserved in terms of gene structures, protein sequences, and motifs. The light response and hormone response elements were included in the BjuAOP2 genes’ cis-regulatory elements. The expression pattern of BjuAOP2 genes was influenced by the different stages of development and the type of tissue being examined. The BjuAOP2 proteins were used to perform the heterologous expression experiment. The results showed that all the five BjuAOP2 proteins can catalyze the conversion of GIB to SIN with different catalytic activity. These results provide the basis for further investigation of the functional study of BjuAOP2 in Tumorous stem mustard glucosinolate biosynthesis.
... Three experimentally obtained GRNs were used for further validation of the predicted network. An accumulation of publicly available Y1H data from the literature was used to generate a Y1H network containing 2,759 interactions [76][77][78][79] The overlap between the iGRN and three experimentally determined GRNs was evaluated by counting how many interactions from the experimental networks were present in the integrative network. The enrichment between two networks was defined as the number of interactions that are present in both networks divided by the number of interactions expected by chance, as explained above. ...
... In most Brassica plants, IGS metabolism is evolutionarily ancient and has been largely retained (Bednarek et al., 2011;Edger et al., 2015). Glucosinolate metabolic pathway is crucial for the innate immune system and their transcriptional regulatory networks have been well studied in model plants 2007;Frerigmann and Gigolashvili, 2014;Li et al., 2014Li et al., , 2020. As a diverse family of secondary metabolites, glucosinolates can be divided into three groups, indolic, aliphatic, and aromatic glucosinolates, depending on their amino acid precursors (Grubb and Abel, 2006;Sønderby et al., 2010). ...
The tryptophan (Trp)‐derived plant secondary metabolites, including camalexin, 4‐hydroxy‐indole‐3‐carbonylnitrile, and indolic glucosinolate (IGS), show broad‐spectrum antifungal activity. However, the distinct regulations of these metabolic pathways among different plant species in response to fungus infection are rarely studied. In this study, our results revealed that WRKY33 directly regulates IGS biosynthesis, notably the production of 4‐methoxyindole‐3‐ylmethyl glucosinolate (4MI3G), conferring resistance to Alternaria brassicicola, an important pathogen which causes black spot in Brassica crops. WRKY33 directly activates the expression of CYP81F2, IGMT1, and IGMT2 to drive side‐chain modification of indole‐3‐ylmethyl glucosinolate (I3G) to 4MI3G, in both Arabidopsis and Chinese kale (Brassica oleracea var. alboglabra Bailey). However, Chinese kale showed a more severe symptom than Arabidopsis when infected by Alternaria brassicicola. Comparative analyses of the origin and evolution of Trp metabolism indicate that the loss of camalexin biosynthesis in Brassica crops during evolution might attenuate the resistance of crops to Alternaria brassicicola. As a result, the IGS metabolic pathway mediated by WRKY33 becomes essential for Chinese kale to deter Alternaria brassicicola. Our results highlight the differential regulation of Trp‐derived camalexin and IGS biosynthetic pathways in plant immunity between Arabidopsis and Brassica crops.
... The MYB factors cooperate in their function with bHLH factors forming larger regulatory complexes (Schweizer et al., 2013). In addition to these factors with large effect on the pathway, another 22 were shown to control accumulation of at least some glucosinolates (Li et al., 2014). Other approaches looking for regulatory elements of sulfur homeostasis using quantitative genetics pointed instead to the importance of metabolic processes. ...
Sulfur is an indispensable nutrient for all organisms as a constituent of amino acids cysteine and methionine and a range of vital cofactors and coenzymes. Because animals and humans cannot assimilate the most common sulfur source, sulfate, they are dependent on a supply of reduced sulfur, mainly in the form of the essential amino acid methionine. Plants are capable of sulfate assimilation and, therefore, plant proteins are the most important source of sulfur in animal and human diets. The growing human population and the changing environment are great challenges for ensuring food security for future generations. Sulfur is one of the nutrients under risk of being deficient in food, because of the reduced atmospheric deposits and the reduction of protein content in grains as a consequence of increased carbon dioxide concentration in the air. To mitigate the potential sulfur deficiency, more has to be understood about the impact of the changing environment on crop yields and quality. In this review, the current knowledge of the impact of the changing environment on plant sulfur metabolism will be reviewed and the consequences for human nutrition and food security will be discussed with the aim to identify knowledge gaps and propose research directions to ensure sufficient sulfur in food for future generations.
