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Arabidopsis auxin signaling mutants show increased resistance to Fusarium oxysporum. Mutants and their respective wild-type (Col or Ler) plants were inoculated with F. oxysporum and disease severity was accessed 8 days after inoculations. Average data from three independent inoculation experiments with standard error are shown in B and E through H; * and ** refer to significant differences at P < 0.05 and 0.01, respectively.
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We report on the early response of Arabidopsis thaliana to the obligate biotrophic pathogen Plasmodiophora brassicae at the hormone and proteome level. Using a CYCB1;1::GUS construct, the re-initiation of infection-related cell division is shown from 4 days after inoculation on. Sensitivity to cytokinins and auxins as well as the endogenous hormone...
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... the auxin-signaling mutants tested, axr1, axr2, axr3, and sgt1b showed increased F. oxysporum resistance, as evidenced by delayed symptom development relative to wild-type plants ( Fig. 6A to G) whereas no significant difference in disease resis- tance between tir1 and wild-type plants was evident (Fig. ...
Context 2
... the auxin-signaling mutants tested, axr1, axr2, axr3, and sgt1b showed increased F. oxysporum resistance, as evidenced by delayed symptom development relative to wild-type plants ( Fig. 6A to G) whereas no significant difference in disease resis- tance between tir1 and wild-type plants was evident (Fig. ...
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... BraA10g022070.3C, BraA10g022080.3C) was upregulated, strengthening the result that auxin and cytokines play a key role during gall formation (Devos et al., 2006). The cytochrome P450 (CYP) superfamily catalyzes a wide range of reactions and plays important roles in several fundamental biological processes, such as steroid synthesis, fatty acid metabolism, and chemical defense (Pankov et al., 2021). ...
Clubroot disease, which is caused by the obligate biotrophic protist Plasmodiophora brassicae, leads to the formation of galls, commonly known as pathogen-induced tumors, on the roots of infected plants. The identification of crucial regulators of host tumor formation is essential to unravel the mechanisms underlying the proliferation and differentiation of P. brassicae within plant cells. To gain insight into this process, transcriptomic analysis was conducted to identify key genes associated with both primary and secondary infection of P. brassicae in Chinese cabbage. Our results demonstrate that the k-means clustering of subclass 1, which exhibited specific trends, was closely linked to the infection process of P. brassicae. Of the 1610 differentially expressed genes (DEGs) annotated in subclass 1, 782 were identified as transcription factors belonging to 49 transcription factor families, including bHLH, B3, NAC, MYB_related, WRKY, bZIP, C2H2, and ERF. In the primary infection, several genes, including the predicted Brassica rapa probable pectate lyase, RPM1-interacting protein 4-like, L-type lectin-domain-containing receptor kinase, G-type lectin S-receptor-like serine, B. rapa photosystem II 22 kDa protein, and MLP-like protein, showed significant upregulation. In the secondary infection stage, 45 of 50 overlapping DEGs were upregulated. These upregulated DEGs included the predicted B. rapa endoglucanase, long-chain acyl-CoA synthetase, WRKY transcription factor, NAC domain-containing protein, cell division control protein, auxin-induced protein, and protein variation in compound-triggered root growth response-like and xyloglucan glycosyltransferases. In both the primary and secondary infection stages, the DEGs were predicted to be Brassica rapa putative disease resistance proteins, L-type lectin domain-containing receptor kinases, ferredoxin-NADP reductases, 1-aminocyclopropane-1-carboxylate synthases, histone deacetylases, UDP-glycosyltransferases, putative glycerol-3-phosphate transporters, and chlorophyll a-binding proteins, which are closely associated with plant defense responses, biosynthetic processes, carbohydrate transport, and photosynthesis. This study revealed the pivotal role of transcription factors in the initiation of infection and establishment of intracellular parasitic relationships during the primary infection stage, as well as the proliferation and differentiation of the pathogen within the host cell during the secondary infection stage.
... Auxin, a hormone widely present in plants, plays an important role in regulating plant growth and development, such as cell proliferation and specialization, organogenesis and morphogenesis, and meristem maintenance (Reinhardt 2003;Benková et al. 2003;Bohn-Courseau 2010, Berleth andSachs 2001;Devos et al. 2006;Schuller et al. 2014). Synthesized predominantly in vigorous and rapidly dividing plant tissues, auxin is then distributed to various tissues and organs, where it exerts regulatory effects through diffusion and polar transport (Friml 2003;Gälweiler et al. 1998). ...
The PIN (PIN-formed) proteins act as vital carriers, regulating auxin polar transport and playing a crucial role in plant growth and development. Cymbidium ensifolium (Orchidaceae) is a perennial herbaceous plant highly esteemed for its high ornamental value. The lotus-shape flowers of C. ensifolium are favored by consumers for their distinctive flower shape with shorter petals. To deepen our understanding of the members and characteristics of PIN gene family in C. ensifolium, this study performed genome-wide identification and analysis of CePIN members, including their physicochemical properties, protein and gene structures, conserved motifs, phylogenetic evolution, promoter components, and expression patterns. The results revealed a total of 16 PIN gene family members in the genome of C. ensifolium. Expression analysis demonstrated significant differential expression of all 16 CePINs across different tissues. Notably, a close correlation was observed between the expression of CePIN1a and CePIN3 and the formation of lotus-shape flowers in C. ensifolium. These findings provide a foundational understanding for further exploration of CePIN functions and offer valuable insights for studying petal development in C. ensifolium.
... Subsequently, indole-3-acetic acid (IAA, auxin) is produced from IAN by nitrilase. The involvement of myrosinases in clubroot formation has been suggested by several studies, but consistent results have not been obtained across plant species or infection stages (Grsic et al., 1999;Devos et al., 2006). Furthermore, several studies have shown that nitrilase genes, including AtNIT1 and AtNIT2 in Arabidopsis, BrNIT-T1 in turnip, and BrNIT2 in B. rapa ssp. ...
... A number of comparative transcriptome and proteome analyses suggest that host development is largely reprogrammed by infection with P. brassicae (Devos et al., 2006;Siemens et al., 2006;Ning et al., 2019;Olszak et al., 2019;Li et al., 2020;Wei et al., 2021;Yuan et al., 2021;Wang et al., 2022). The release of effectors is a well-known strategy by which pathogens hijack host metabolic processes or suppress host resistance (Hogenhout et al., 2009;Kazan and Lyons, 2014). ...
The protist pathogen Plasmodiophora brassicae hijacks the metabolism and development of host cruciferous plants and induces clubroot formation, but little is known about its regulatory mechanisms. Previously, the Pnit2int2 sequence, a sequence around the second intron of the nitrilase gene (BrNIT2) involved in auxin biosynthesis in Brassica rapa ssp. pekinensis, was identified as a specific promoter activated during clubroot formation. In this study, we hypothesized that analysis of the transcriptional regulation of Pnit2int2 could reveal how P. brassicae affects the host gene regulatory system during clubroot development. By yeast one-hybrid screening, the pathogen zinc finger protein PbZFE1 was identified to specifically bind to Pnit2int2. Specific binding of PbZFE1 to Pnit2int2 was also confirmed by electrophoretic mobility shift assay. The binding site of PbZFE1 is essential for promoter activity of Pnit2int2 in clubbed roots of transgenic Arabidopsis thaliana (Pnit2int2-2::GUS), indicating that PbZFE1 is secreted from P. brassicae and functions within plant cells. Ectopic expression of PbZEF1 in A. thaliana delayed growth and flowering time, suggesting that PbZFE1 has significant impacts on host development and metabolic systems. Thus, P. brassicae appears to secrete PbZFE1 into host cells as a transcription factor-type effector during pathogenesis.
... In plant hormone signal transduction, the process of growth hormone signal transduction is divided into two steps, firstly, the tryptophan metabolism pathway synthesizes AUX1 and activates the transport inhibitor response protein (TIR1); then, the transport inhibitor response protein mediates ubiquitylation and inhibits the growth hormone response factor ARF, which is released from the dissociation of AUX/IAA, to activate the transcription process [59,60]. Growth hormone acts as a "molecular glue" that enhances the interaction of Aux/IAA with TIR1 [61]. TIR1 recognizes and is induced by AUX1 [62]. ...
Pepper (Capsicum annuum L.) is one of the most widely grown vegetable crops in China, with widespread cultivation worldwide. Fruit weight (size) is a complex trait controlled by multiple factors and is an essential determinant of pepper yield. In this study, we analyzed the transcriptome of two pepper recombinant lines with different fruit weights, ‘B302’ and ‘B400’, at five developmental stages to reveal some of the differentially expressed genes and mechanisms controlling fruit weight. The results showed that 21,878 differential genes were identified between the two specimens. Further analysis of the differentially expressed genes revealed that Boron transporter 4 was significantly highly expressed in the large-fruited pepper and almost not expressed at all in the small-fruited pepper. CaAUX1, CaAUX/IAA, CaGH3, CaSAUR, and other related genes in the Auxin signal transduction pathway were highly expressed in the large-fruited pepper but significantly reduced in the small-fruited pepper. In addition, a comparison of differentially expressed transcription factors at different times revealed that transcription factors such as CaMADS3, CaAGL8, CaATHB13, and CaATHB-40 were highly differentially expressed in the large-fruited pepper, and these transcription factors may be related to pepper fruit expansion. Through weighted gene co-expression network analysis (WGCNA), the MEorangered4 module was shown to have a highly significant correlation with fruit weight, and the key modules were analyzed by constructing the hub core gene network interactions map and core genes regulating fruit weight such as APETALA 2 were found. In conclusion, we find that the expression of relevant genes at different developmental stages was different in ‘B302’ and ‘B400’, and it was hypothesized that these genes play essential roles in the development of fruit size and that the interactions occurring between transcription factors and phytohormones may regulate the development of fruit size.
... The clubroot pathogen and Brassicaceae crops establish a specific relationship where plant hormones are involved in triggering immune responses and orchestrating diseasephase-dependent transcriptomic changes [11]. In addition to SA, other groups of plant hormones are involved in different stages of disease progression, especially cytokinin (CK) and auxin, two key players in plant organ development [12,13]. By manipulating CK and auxin levels, the pathogen promotes hypertrophy and cell division by reprogramming meristematic activity in infected roots, leading to the formation of root galls [13][14][15]. ...
... Increased CK levels promoting cell division were observed in the early stage of clubroot disease in Arabidopsis. Conversely, reduced CK levels and concomitant downregulation in the expression of host plant CK sensing and metabolism-related genes were observed in the late stage of infection [12,13,16]. Shifts in CK and auxin homeostasis in developing galls can potentially influence the progression of the clubroot disease; it was reported by Siemens et al. that plants constitutively overexpressing cytokinin oxidase/dehydrogenase show reduced disease symptoms [13]. ...
... In our experiments, the levels of free IAA were only mildly affected in response to the infection process, but treatments with 10 µmol L −1 PI-55 seemed to produce more significant effects. This suggests that auxin homeostasis may also be affected by CK antagonist treatment, but further experiments will be needed to understand the hormone's role in the process, as IAA levels change quite dynamically from early to later stages of infection [12]. ...
Plasmodiophora brassicae is an obligate biotrophic pathogen causing clubroot disease in cruciferous plants. Infected plant organs are subject to profound morphological changes, the roots form characteristic galls, and the leaves are chlorotic and abscise. The process of gall formation is governed by timely changes in the levels of endogenous plant hormones that occur throughout the entire life cycle of the clubroot pathogen. The homeostasis of two plant hormones, cytokinin and auxin, appears to be crucial for club development. To investigate the role of cytokinin and auxin in gall formation, we used metabolomic and transcriptomic profiling of Arabidopsis thaliana infected with clubroot, focusing on the late stages of the disease, where symptoms were more pronounced. Loss-of-function mutants of three cytokinin receptors, AHK2, AHK3, and CRE1/AHK4, were employed to further study the homeostasis of cytokinin in response to disease progression; ahk double mutants developed characteristic symptoms of the disease, albeit with varying intensity. The most susceptible to clubroot disease was the ahk3 ahk4 double mutant, as revealed by measuring its photosynthetic performance. Quantification of phytohormone levels and pharmacological treatment with the cytokinin antagonist PI-55 showed significant changes in the levels of endogenous cytokinin and auxin, which was manifested by both enhanced and reduced development of disease symptoms in different genotypes.
... It has been established that plasmodia produce cytokinins to re-initiate cell growth and division, driving the establishment of a new meristematic area [125]. Once established, pathogen-derived cytokinins are used to synthesize IAA, reinforcing a hypothesis that auxins, together with cytokinins, play a key role during gall formation [125,126]. Transcriptomic analyses performed upon Chinese cabbage and Arabidopsis revealed several DEG related to auxin pathways following clubroot infection [125,127]. Among these, we identified several genes implicated in auxin biosynthesis as well as genes involved in auxin homeostasis, such as nitriles and members of the GH3 family or the auxin receptors TIR1 (TRANSPORT INHIBITOR RESPONSE 1) and AFB1 (AUXIN SIGNALING F BOX PROTEIN 1) [15,28,[125][126][127][128]. ...
... Transcriptomic analyses performed upon Chinese cabbage and Arabidopsis revealed several DEG related to auxin pathways following clubroot infection [125,127]. Among these, we identified several genes implicated in auxin biosynthesis as well as genes involved in auxin homeostasis, such as nitriles and members of the GH3 family or the auxin receptors TIR1 (TRANSPORT INHIBITOR RESPONSE 1) and AFB1 (AUXIN SIGNALING F BOX PROTEIN 1) [15,28,[125][126][127][128]. ...
Plasmodiophora brassicae Wor., the clubroot pathogen, is the perfect example of an “atypical” plant pathogen. This soil-borne protist and obligate biotrophic parasite infects the roots of cruciferous crops, inducing galls or clubs that lead to wilting, loss of productivity, and plant death. Unlike many other agriculturally relevant pathosystems, research into the molecular mechanisms that underlie clubroot disease and Plasmodiophora-host interactions is limited. After release of the first P. brassicae genome sequence and subsequent availability of transcriptomic data, the clubroot research community have implicated the involvement of phytohormones during the clubroot pathogen’s manipulation of host development. Herein we review the main events leading to the formation of root galls and describe how modulation of select phytohormones may be key to modulating development of the plant host to the benefit of the pathogen. Effector-host interactions are at the base of different strategies employed by pathogens to hijack plant cellular processes. This is how we suspect the clubroot pathogen hijacks host plant metabolism and development to induce nutrient-sink roots galls, emphasizing a need to deepen our understanding of this master manipulator.
... Both auxin and Et can inhibit root elongation and lateral root development, which can contribute to the formation of gall in the root [45]. Previous studies reported that JA expression is up-regulated after P. brassicae infection because JA induces the expression of 1-3-methylthiogluconic acid (GSL) and wax hydrolase, which is the key material for auxin synthesis [46]. It is possible that the JA metabolic pathway and auxin metabolic pathway may be related during the occurrence of clubroot disease. ...
Clubroot is an infectious root disease caused by Plasmodiophora brassicae in Brassica crops, which can cause immeasurable losses. We analyzed integrative transcriptome, small RNAs, degradome, and phytohormone comprehensively to explore the infection mechanism of P. brassicae. In this study, root samples of Brassica rapa resistant line material BrT24 (R-line) and susceptible line material Y510-9 (S-line) were collected at four different time points for cytological, transcriptome, miRNA, and degradome analyses. We found the critical period of disease resistance and infection were at 0–3 DAI (days after inoculation) and 9–20 DAI, respectively. Based on our finding, we further analyzed the data of 9 DAI vs. 20 DAI of S-line and predicted the key genes ARF8, NAC1, NAC4, TCP10, SPL14, REV, and AtHB, which were related to clubroot disease development and regulating disease resistance mechanisms. These genes are mainly related to auxin, cytokinin, jasmonic acid, and ethylene cycles. We proposed a regulatory model of plant hormones under the mRNA–miRNA regulation in the critical period of P. brassicae infection by using the present data of the integrative transcriptome, small RNAs, degradome, and phytohormone with our previously published results. Our integrative analysis provided new insights into the regulation relationship of miRNAs and plant hormones during the process of disease infection with P. brassicae.
... Clubroot, caused by a protist Plasmodiophora brassicae, is a common and very important disease on cruciferous crops (Hwang et al. 2012;Dixon 2014;Liu et al. 2020). Previous research showed that P. brassicae invades plants via root hairs and lives intracellularly in cortical cells; the protist can also induce de-differentiation of host cortical cells and subsequent cell division by stimulating the synthesis of auxins, cytokinins, brassinosteroids, and flavonoids in the invaded host cells (Devos et al. 2006;Päsold et al. 2010;Jahn et al. 2013;Ludwig-müller, 2014;Malinowski et al. 2016;Zhao et al. 2017a). Consequently, the pathogen induces the formation of tumors (or galls) and results in the distortion and dysfunction of roots. ...
... P. brassicae might decrease cell wall integrity of root hairs to allow the entry of zoospores. Auxin homeostasis plays an essential role during P. brassicae infection and gall formation, and plant hormones such as cytokinins, auxin, and brassinosteroids are involved in symptom development (Devos et al. 2006;Jahn et al. 2013;Jahn et al. 2014). Flavonoids are highly produced in root galls formed on Arabidopsis (Päsold et al. 2010), and the induction of these secondary metabolites was also detected in P. brassicae-infected roots in the present The length and weight of aerial parts and roots; MH, M. huakuii-inoculated seedlings; PB, P. brassicae-inoculated seedlings; PB + MH, P. brassicae, and M. huakuii co-inoculated seedlings. ...
Over 110 million tons of nitrogen fertilizer every year is used for crop production. Scientists have dreamed of enabling rhizobial nitrogen fixation in non-leguminous crops to mitigate the increasing demand for nitrogen fertilizer. However, despite decades of research, rhizobial nitrogen fixation in non-host plants has not been demonstrated. Here, we reported that an N-fixing rhizobium and a clubroot pathogen Plasmodiophora brassicae exhibited a synergistic effect on fixing nitrogen in cruciferous plants. Rhizobia were found to invade P. brassicae -infected rapeseed ( Brassica napus ) roots in the field. The colonization of rhizobium on rapeseed roots was confirmed by co-inoculating Mesorhizobium huakuii with P. brassicae under controlled laboratory conditions. M. huakuii infection could alleviate clubroot symptoms and promote the growth of diseased rapeseeds. M. huakuii could fix nitrogen in P. brassicae -infected plants based on the results of ¹⁵ N isotope dilution tests. The expression of homologs of legume genes required for symbiosis and early-nodulin genes was significantly upregulated in Arabidopsis during early infection by P. brassicae . More importantly, M. huakuii could even fix nitrogen in P. brassicae -resistant rapeseed cultivar and promote plant growth when co-inoculated with P. brassicae . Our findings provide a new avenue to understand the interaction of rhizobia with non-host plants, stimulate the exploration of fixing nitrogen in non-leguminous plants by nitrogen-fixing rhizobia, and develop a strategy for both disease control and nitrogen fixation on non-host crops.
... Both auxin and ethylene are inhibited root elongation and lateral root development which contribute to formation of gall in root (Woodward and Bartel 2005). Previous studies were reported that JA expression is up-regulated after P. brassicae infection because JA induces the expression of 1-3-methylthiogluconic acid (GSL) and wax hydrolase which is the key material for auxin synthesis (Devos et al. 2006). It is possible that JA metabolic pathway and auxin metabolic pathway may be related during the occurrence of clubroot disease. ...
Background and aim Clubroot is an infectious root disease caused by Plasmodiophora brassicae in Brassica crops, which can cause immeasurable losses. We aimed to explore the infection mechanism under P. brassicae integrating transcriptome, small RNA, degradome and phytohormone technology .
Result In this study, root samples of Brassica rapa resistant line BrT24 (R-line) and susceptible line Y510-9 (S-line) were collected at four different time points for cytological, transcriptome, miRNA and degradome investigations. We found the critical period of disease resistance and infection at 0 - 3 days and 9 - 20 days, respectively. Based on our finding we further analyzed the data of 9 d vs 20 d of S-line and predicted the key genes ARF8 , NAC1 , NAC4 , TCP10 , SPL14 , REV and ATHB related to clubroot disease development and regulating disease resistance mechanisms. These genes are mainly related to auxin, cytokinin, jasmonic acid and ethylene cycles. We proposed a regulatory model of plant hormones under the mRNA-miRNA regulation in the critical period of P. brassicae infection by using integrative transcriptome, small RNA, degradome and phytohormone technology.
Conclusion Our integrative analysis found that the bra-miR164/NAC1/4 , bra-miR319/TCP10 and bra-miR167/ARF8 were associated with clubroot symptoms development, which provide new insights into the regulation relationship of miRNA and plant hormones during the process of disease infection .
... The root-protein profile of a susceptible canola genotype revealed the crucial role of cytokinin in the early phases of clubroot infection [199]. Though cytokinin increases in the early response to P. brassicae infection [181,200], it was reportedly down-regulated at later stages of gall development [180,181]. However, Laila et al. [201] reported the induction of several cytokinin biosynthetic and signaling genes at early and late stages of infection in both root and leaf tissues of Chinese cabbage. ...
... The down-regulation of cytokinin can be a part of the plant-defence mechanism against P. brassicae. It reduces the signals involved in cell division and the cell cycle progression in the root cortex [200]. Disturbing the balance of cytokinin synthesis and degradation may impact clubroot disease progression. ...
Brassica oleracea is an agronomically important species of the Brassicaceae family, including several nutrient-rich vegetables grown and consumed across the continents. But its sustainability is heavily constrained by a range of destructive pathogens, among which, clubroot disease, caused by a biotrophic protist Plasmodiophora brassicae, has caused significant yield and economic losses worldwide, thereby threatening global food security. To counter the pathogen attack, it demands a better understanding of the complex phenomenon of Brassica-P. brassicae pathosystem at the physiological, biochemical, molecular, and cellular levels. In recent years, multiple omics technologies with high-throughput techniques have emerged as successful in elucidating the responses to biotic and abiotic stresses. In Brassica spp., omics technologies such as genomics, transcriptomics, ncRNAomics, proteomics, and metabolomics are well documented, allowing us to gain insights into the dynamic changes that transpired during host-pathogen interactions at a deeper level. So, it is critical that we must review the recent advances in omics approaches and discuss how the current knowledge in multi-omics technologies has been able to breed high-quality clubroot-resistant B. oleracea. This review highlights the recent advances made in utilizing various omics approaches to understand the host resistance mechanisms adopted by Brassica crops in response to the P. brassicae attack. Finally, we have discussed the bottlenecks and the way forward to overcome the persisting knowledge gaps in delivering solutions to breed clubroot-resistant Brassica crops in a holistic, targeted, and precise way.
