Ceramides regulate defense response by binding to RbohD in Arabidopsis

Abstract Background Hemibiotrophic pathogen such as the fungal pathogen Ganoderma boninense that is destructive to oil palm, manipulates host defense mechanism by strategically switching from biotrophic to necrotrophic phase. Our previous study revealed two distinguishable expression profiles of oil palm genes that formed the basis in deducing biotrophic phase at early interaction which switched to necrotrophic phase at a later stage of infection. Results The present report is a continuing study from our previous published transcriptomic profiling of oil palm seedlings against G. boninense. We focused on identifying differentially expressed genes (DEGs) encoding transcription factors (TFs) from the same RNA-seq data; resulting in 106 upregulated and 108 downregulated TFs being identified. The DEGs are involved in four established defense-related pathways responsible for cell wall modification, reactive oxygen species (ROS)-mediated signaling, programmed cell death (PCD) and plant innate immunity. We discovered upregulation of JUNGBRUNNEN 1 (EgJUB1) during the fungal biotrophic phase while Ethylene Responsive Factor 113 (EgERF113) demonstrated prominent upregulation when the palm switches to defense against necrotrophic phase. EgJUB1 was shown to have a binding activity to a 19 bp palindromic SNBE1 element, WNNYBTNNNNNNNAMGNHW found in the promoter region of co-expressing EgHSFC-2b. Further in silico analysis of promoter regions revealed co-expression of EgJUB1 with TFs containing SNBE1 element with single nucleotide change at either the 5th or 18th position. Meanwhile, EgERF113 binds to both GCC and DRE/CRT elements promoting plasticity in upregulating the downstream defense-related genes. Both TFs were proven to be nuclear-localized based on subcellular localization experiment using onion epidermal cells. Conclusion Our findings demonstrated unprecedented transcriptional reprogramming of specific TFs potentially to enable regulation of a specific set of genes during different infection phases of this hemibiotrophic fungal pathogen. The results propose the intricacy of oil palm defense response in orchestrating EgJUB1 during biotrophic and EgERF113 during the subsequent transition to the necrotrophic phase. Binding of EgJUB1 to SNBE motif instead of NACBS while EgERF113 to GCC-box and DRE/CRT motifs is unconventional and not normally associated with pathogen infection. Identification of these phase-specific oil palm TFs is important in designing strategies to tackle or attenuate the progress of infection.

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Root exposure to apple replant disease soil triggers local defense response and rhizoplane microbiome dysbiosis

FEMS Microbiology Ecology ◽

10.1093/femsec/fiab031 ◽

2021 ◽

Author(s):

Alicia Balbín-Suárez ◽

Samuel Jacquiod ◽

Annmarie-Deetja Rohr ◽

Benye Liu ◽

Henryk Flachowsky ◽

...

Keyword(s):

Gene Expression ◽

Plant Defense ◽

Defense Response ◽

Soil Column ◽

Soil Layer ◽

Soil Microbiome ◽

Control Soil ◽

Apple Rootstocks ◽

Apple Replant Disease ◽

Replant Disease

Abstract A soil column split-root experiment was designed to investigate the ability of apple replant disease (ARD) causing agents to spread in soil. ‘M26’ apple rootstocks grew into a top layer of Control soil, followed by a barrier-free split-soil layer (Control soil/ARD soil). We observed a severely reduced root growth, concomitant with enhanced gene expression of phytoalexin biosynthetic genes and phytoalexin content in roots from ARD soil, indicating a pronounced local plant defense response. Amplicon sequencing (bacteria, archaea, fungi) revealed local shifts in diversity and composition of microorganisms in the rhizoplane of roots from ARD soil. An enrichment of OTUs affiliated to potential ARD fungal pathogens (Ilyonectria and Nectria sp.) and bacteria frequently associated with ARD (Streptomyces, Variovorax) was noted. In conclusion, our integrated study supports the idea of ARD being local and not spreading into surrounding soil, as only the roots in ARD soil were affected in terms of growth, phytoalexin biosynthetic gene expression, phytoalexin production, and altered microbiome structure. This study further reinforces the microbiological nature of ARD, being likely triggered by a disturbed soil microbiome enriched with low mobility ARD-causing agents that induce a strong plant defense and rhizoplane microbiome dysbiosis, concurring with root damage.

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Nucleotide-Binding Leucine-Rich Repeat Genes CsRSF1 and CsRSF2 Are Positive Modulators in the Cucumis sativus Defense Response to Sphaerotheca fuliginea

International Journal of Molecular Sciences ◽

10.3390/ijms22083986 ◽

2021 ◽

Vol 22 (8) ◽

pp. 3986

Author(s):

Xue Wang ◽

Qiumin Chen ◽

Jingnan Huang ◽

Xiangnan Meng ◽

Na Cui ◽

...

Keyword(s):

Cell Membrane ◽

Defense Response ◽

Nucleotide Binding ◽

Plant Defense Response ◽

Sphaerotheca Fuliginea ◽

Leucine Rich Repeat ◽

Transcript Levels ◽

Yield And Quality ◽

Leucine Rich Repeats ◽

Exogenous Substances

Cucumber powdery mildew caused by Sphaerotheca fuliginea is a leaf disease that seriously affects cucumber’s yield and quality. This study aimed to report two nucleotide-binding site-leucine-rich repeats (NBS-LRR) genes CsRSF1 and CsRSF2, which participated in regulating the resistance of cucumber to S. fuliginea. The subcellular localization showed that the CsRSF1 protein was localized in the nucleus, cytoplasm, and cell membrane, while the CsRSF2 protein was localized in the cell membrane and cytoplasm. In addition, the transcript levels of CsRSF1 and CsRSF2 were different between resistant and susceptible cultivars after treatment with exogenous substances, such as abscisic acid (ABA), methyl jasmonate (MeJA), salicylic acid (SA), ethephon (ETH), gibberellin (GA) and hydrogen peroxide (H2O2). The expression analysis showed that the transcript levels of CsRSF1 and CsRSF2 were correlated with plant defense response against S. fuliginea. Moreover, the silencing of CsRSF1 and CsRSF2 impaired host resistance to S. fuliginea, but CsRSF1 and CsRSF2 overexpression improved resistance to S. fuliginea in cucumber. These results showed that CsRSF1 and CsRSF2 genes positively contributed to the resistance of cucumber to S. fuliginea. At the same time, CsRSF1 and CsRSF2 genes could also regulate the expression of defense-related genes. The findings of this study might help enhance the resistance of cucumber to S. fuliginea.

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Citric acid inhibits Cd uptake by improving the preferential transport of Mn and triggering the defense response of amino acids in grains

Ecotoxicology and Environmental Safety ◽

10.1016/j.ecoenv.2021.111921 ◽

2021 ◽

Vol 211 ◽

pp. 111921

Author(s):

Weijie Xue ◽

Peipei Wang ◽

Li Tang ◽

Changbo Zhang ◽

Changrong Wang ◽

...

Keyword(s):

Amino Acids ◽

Citric Acid ◽

Defense Response ◽

Cd Uptake ◽

Preferential Transport

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GhKWL1 Upregulates GhERF105 but Its Function Is Impaired by Binding with VdISC1, a Pathogenic Effector of Verticillium dahliae

International Journal of Molecular Sciences ◽

10.3390/ijms22147328 ◽

2021 ◽

Vol 22 (14) ◽

pp. 7328

Author(s):

Yang Chen ◽

Mi Zhang ◽

Lei Wang ◽

Xiaohan Yu ◽

Xianbi Li ◽

...

Keyword(s):

Gene Expression ◽

Transgenic Plants ◽

Gossypium Hirsutum ◽

Verticillium Wilt ◽

Verticillium Dahliae ◽

Defense Response ◽

Upland Cotton ◽

Effector Protein ◽

Positive Regulator ◽

Its Gene

Verticillium wilt, caused by Verticillium dahliae, is a devastating disease for many important crops, including cotton. Kiwellins (KWLs), a group of cysteine-rich proteins synthesized in many plants, have been shown to be involved in response to various phytopathogens. To evaluate genes for their function in resistance to Verticillium wilt, we investigated KWL homologs in cotton. Thirty-five KWL genes (GhKWLs) were identified from the genome of upland cotton (Gossypium hirsutum). Among them, GhKWL1 was shown to be localized in nucleus and cytosol, and its gene expression is induced by the infection of V. dahliae. We revealed that GhKWL1 was a positive regulator of GhERF105. Silencing of GhKWL1 resulted in a decrease, whereas overexpression led to an increase in resistance of transgenic plants to Verticillium wilt. Interestingly, through binding to GhKWL1, the pathogenic effector protein VdISC1 produced by V. dahliae could impair the defense response mediated by GhKWL1. Therefore, our study suggests there is a GhKWL1-mediated defense response in cotton, which can be hijacked by V. dahliae through the interaction of VdISC1 with GhKWL1.

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Unraveling the Metabolite Signature of Endophytic Bacillus velezensis Strain Showing Defense Response Towards Fusarium oxysporum

Agronomy ◽

10.3390/agronomy11040683 ◽

2021 ◽

Vol 11 (4) ◽

pp. 683

Author(s):

Yang Cao ◽

Wei Ding ◽

Chang Liu

Keyword(s):

Fusarium Oxysporum ◽

Inhibitory Activity ◽

Defense Response ◽

Endophytic Bacteria ◽

Rice Seedling ◽

Seedling Blight ◽

Bacillus Velezensis ◽

Secondary Bile Acid ◽

Pathogen Inhibition

Seedling blight, caused by the fungus Fusarium oxysporum, significantly lowers rice production globally. Earlier reports have opined that endophytic bacteria strains could be possible biocontrol agents, but the mechanistic actions involved are still unclear. Therefore, this study aimed to isolate the endophytic bacteria with high inhibitory activity and elucidate its possible mechanisms for inducing resistance by metabolomics. The results showed that mdj-36 had the strongest in vitro pathogen inhibition of F. oxysporum, while mdj-34 displayed the lowest inhibitory activity identified as Bacillus velezensis strains. Metabolomic analyses demonstrated that B. velezensis mdj-36 growth medium could produce higher organic acids, terpenes, and diterpene than B. velezensis mdj-34. Further investigation revealed that ‘secondary bile acid biosynthesis’ and ‘glycerophospholipid metabolism’ pathways played essential roles in defense response towards F. oxysporum. This study’s findings provide a credible theoretical basis for the possible use of the B. velezensis strain against rice seedling blight.

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Transcriptomic and genetic approaches reveal an essential role of the NAC transcription factor SlNAP1 in the growth and defense response of tomato

Horticulture Research ◽

10.1038/s41438-020-00442-6 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Jiao Wang ◽

Chenfei Zheng ◽

Xiangqi Shao ◽

Zhangjian Hu ◽

Jianxin Li ◽

...

Keyword(s):

Pseudomonas Syringae ◽

Defense Response ◽

Global Climate ◽

Plant Responses ◽

Multiple Stresses ◽

Bacterial Diseases ◽

Bacterial Wilt Disease ◽

Transgenic Lines ◽

Breeding Target

AbstractWith global climate change, plants are frequently being exposed to various stresses, such as pathogen attack, drought, and extreme temperatures. Transcription factors (TFs) play crucial roles in numerous plant biological processes; however, the functions of many tomato (Solanum lycopersicum L.) TFs that regulate plant responses to multiple stresses are largely unknown. Here, using an RNA-seq approach, we identified SlNAP1, a NAC TF-encoding gene, which was strongly induced by various stresses. By generating SlNAP1 transgenic lines and evaluating their responses to biotic and abiotic stresses in tomato, we found that SlNAP1-overexpressing plants showed significantly enhanced defense against two widespread bacterial diseases, leaf speck disease, caused by Pseudomonas syringae pv. tomato (Pst) DC3000, and root-borne bacterial wilt disease, caused by Ralstonia solanacearum. In addition, SlNAP1 overexpression dramatically improved drought tolerance in tomato. Although the SlNAP1-overexpressing plants were shorter than the wild-type plants during the early vegetative stage, eventually, their fruit yield increased by 10.7%. Analysis of different hormone contents revealed a reduced level of physiologically active gibberellins (GAs) and an increased level of salicylic acid (SA) and abscisic acid (ABA) in the SlNAP1-overexpressing plants. Moreover, EMSAs and ChIP-qPCR assays showed that SlNAP1 directly activated the transcription of multiple genes involved in GA deactivation and both SA and ABA biosynthesis. Our findings reveal that SlNAP1 is a positive regulator of the tomato defense response against multiple stresses and thus may be a potential breeding target for improving crop yield and stress resistance.

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