scholarly journals Conservation of N-hydroxy-pipecolic acid-mediated systemic acquired resistance in crop plants

2019 ◽  
Author(s):  
Eric C. Holmes ◽  
Yun-Chu Chen ◽  
Elizabeth Sattely ◽  
Mary Beth Mudgett

SUMMARYSignal propagation and the coordination of whole-organism responses in plants rely heavily on small molecules. Systemic acquired resistance (SAR) is one such process in which long-distance signaling activates immune responses in uninfected tissue as a way to limit the spread of a primary, localized infection. Recently, N-hydroxy pipecolic acid (NHP) was discovered and shown to coordinate SAR in Arabidopsis. Here, we provide metabolic and biochemical evidence that NHP is conserved across the plant kingdom and demonstrate a role for NHP in mediating SAR responses in tomato and pepper. We reconstituted the NHP biosynthetic pathway in planta and show that transient expression of two NHP biosynthetic genes in tomato induces enhanced resistance to a bacterial pathogen in distal tissue. Our results suggest engineering strategies to induce NHP-mediated SAR are a promising route to improve broad-spectrum pathogen resistance in crops.IN BRIEFEngineering NHP production is a promising strategy to enhance disease resistance in crops.HIGHLIGHTSArabidopsis N-hydroxy-pipecolic acid (NHP) pathway is conserved across the plant kingdomApplication of NHP to tomato and pepper plants induces a robust SAR responseMetabolic engineering of the Arabidopsis NHP pathway in Solanum lycopersicum leads to enhanced NHP production and defense primingGenetic engineering for enhanced NHP production is a promising strategy to protect crop plants from multiple pathogens

2019 ◽  
Vol 12 (604) ◽  
pp. eaay3066 ◽  
Author(s):  
Eric C. Holmes ◽  
Yun-Chu Chen ◽  
Elizabeth S. Sattely ◽  
Mary Beth Mudgett

Systemic acquired resistance (SAR) is a powerful immune response that triggers broad-spectrum disease resistance throughout a plant. In the model plant Arabidopsis thaliana, long-distance signaling and SAR activation in uninfected tissues occur without circulating immune cells and instead rely on the metabolite N-hydroxy-pipecolic acid (NHP). Engineering SAR in crop plants would enable external control of a plant’s ability to mount a global defense response upon sudden changes in the environment. Such a metabolite-engineering approach would require the molecular machinery for producing and responding to NHP in the crop plant. Here, we used heterologous expression in Nicotiana benthamiana leaves to identify a minimal set of Arabidopsis genes necessary for the biosynthesis of NHP. Local expression of these genes in tomato leaves triggered SAR in distal tissues in the absence of a pathogen, suggesting that the SAR trait can be engineered to enhance a plant’s endogenous ability to respond to pathogens. We also showed tomato produces endogenous NHP in response to a bacterial pathogen and that NHP is present across the plant kingdom, raising the possibility that an engineering strategy to enhance NHP-induced defenses could be possible in many crop plants.


2018 ◽  
Author(s):  
Yun Chu Chen ◽  
Eric C. Holmes ◽  
Jakub Rajniak ◽  
Jung-Gun Kim ◽  
Sandy Tang ◽  
...  

AbstractSystemic acquired resistance (SAR) is a global response in plants induced at the site of infection that leads to long-lasting and broad-spectrum disease resistance at distal, uninfected tissues. Despite the importance of this priming mechanism, the identity of the mobile defense signal that moves systemically throughout plants to initiate SAR has remained elusive. In this paper, we describe a new metabolite, N-hydroxy-pipecolic acid (N-OH-Pip), and provide evidence that this molecule is a mobile signal that plays a central role in initiating SAR signal transduction in Arabidopsis thaliana. We demonstrate that FLAVIN-DEPENDENT MONOOXYGENASE 1 (FMO1), a key regulator of SAR-associated defense priming, can synthesize N-OH-Pip from pipecolic acid in planta, and exogenously applied N-OH-PIP moves systemically in Arabidopsis and can rescue the SAR-deficiency of fmo1 mutants. We also demonstrate that N-OH-Pip treatment causes systemic changes in the expression of pathogenesis-related genes and metabolic pathways throughout the plant, and enhances resistance to a bacterial pathogen. This work provides new insight into the chemical nature of a mobile signal for SAR and also suggests that the N-OH-Pip pathway is a promising target for metabolic engineering to enhance disease resistance.


Author(s):  
Lennart Mohnike ◽  
Dmitrij Rekhter ◽  
Weijie Huang ◽  
Kirstin Feussner ◽  
Hainan Tian ◽  
...  

AbstractThe trade-off between growth and defense is a critical aspect of plant immunity. Therefore, plant immune response needs to be tightly regulated. The hormone regulating plant defense against biotrophic pathogens is salicylic acid (SA). Recently, N-hydroxy-pipecolic acid (NHP) was identified as second regulator for plant innate immunity and systemic acquired resistance. Although the biosynthetic pathway leading to NHP formation has already been identified, the route how NHP is further metabolized was unclear. Here, we present UGT76B1 as a UDP-dependent glycosyltransferase that modifies NHP by catalyzing the formation of 1-O-glucosyl-pipecolic acid (NHP-OGlc). Analysis of T-DNA and CRISPR knock-out mutant lines of UGT76B1 by targeted and non-targeted UHPLC-HRMS underlined NHP and SA as endogenous substrates of this enzyme in response to Pseudomonas infection and UV treatment. UGT76B1 shows similar KM for NHP and SA. ugt76b1 mutant plants have a dwarf phenotype and a constitutive defense response which can be suppressed by loss of function of the NHP biosynthetic enzyme FMO1. This suggests that elevated accumulation of NHP contributes to the enhanced disease resistance in ugt76b1. Externally applied NHP can move to distal tissue in ugt76b1 mutant plants. Although glycosylation is not required for the long distance movement of NHP during systemic acquired resistance, it is crucial to balance growth and defense.


2018 ◽  
Vol 115 (21) ◽  
pp. E4920-E4929 ◽  
Author(s):  
Yun-Chu Chen ◽  
Eric C. Holmes ◽  
Jakub Rajniak ◽  
Jung-Gun Kim ◽  
Sandy Tang ◽  
...  

Systemic acquired resistance (SAR) is a global response in plants induced at the site of infection that leads to long-lasting and broad-spectrum disease resistance at distal, uninfected tissues. Despite the importance of this priming mechanism, the identity and complexity of defense signals that are required to initiate SAR signaling is not well understood. In this paper, we describe a metabolite, N-hydroxy-pipecolic acid (N-OH-Pip) and provide evidence that this mobile molecule plays a role in initiating SAR signal transduction in Arabidopsis thaliana. We demonstrate that FLAVIN-DEPENDENT MONOOXYGENASE 1 (FMO1), a key regulator of SAR-associated defense priming, can synthesize N-OH-Pip from pipecolic acid in planta, and exogenously applied N-OH-Pip moves systemically in Arabidopsis and can rescue the SAR-deficiency of fmo1 mutants. We also demonstrate that N-OH-Pip treatment causes systemic changes in the expression of pathogenesis-related genes and metabolic pathways throughout the plant and enhances resistance to a bacterial pathogen. This work provides insight into the chemical nature of a signal for SAR and also suggests that the N-OH-Pip pathway is a promising target for metabolic engineering to enhance disease resistance.


2016 ◽  
Vol 38 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Robin K. Cameron ◽  
Philip Carella ◽  
Marisa Isaacs ◽  
Marc Champigny ◽  
Juliane Merl-Pham ◽  
...  

2013 ◽  
Vol 4 ◽  
Author(s):  
Marc J. Champigny ◽  
Marisa Isaacs ◽  
Philip Carella ◽  
Jennifer Faubert ◽  
Pierre R. Fobert ◽  
...  

2007 ◽  
Vol 97 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Esther Amzalek ◽  
Yigal Cohen

Four inducers of systemic acquired resistance (SAR) were examined for their efficacy in controlling rust infection caused by Puccinia helianthi in sunflower plants. Of the four compounds, DL-3-amino-n-butanoic acid (DL-β-aminobutyric acid [BABA]) was the most effective and sodium salicylate (NaSA) was the least effective in protecting against rust. In leaf disk assays, full protection was obtained with BABA at 25 μg/ml, benzodiathiazol-S-methyl ester (BTH) at 100 μg/ml, 2,6-di-chloroisonicotinic acid (INA) at 100 μg/ml, and NaSA at >200 μg/ml. L-2-amino-n-butanoic acid (AABA) was partially effective, whereas N-methyl-BABA and 4-aminobutnoic acid (GABA) were ineffective. The R-enantiomer of BABA, but not the S-enantiomer, was more effective than the racemic mixture. In intact plants, BABA applied as a foliar spray or a root dip, before or after (up to 48 h) inoculation, provided significant protection for 8 days. BTH, INA, and NaSA were less protective and more phytotoxic compared with BABA. BABA did not affect urediospore germination, germ tube growth, appressorial formation, or initial ingress of P. helianthi, but strongly suppressed mycelial colonization in the mesophyll and, consequently, pustule and urediospore formation. No accumulation of defense compounds (phenolics, lignin, or callose) was detected in BABA-treated inoculated or noninoculated plants. This is the first report on the activity of BABA against an obligate Basidomycete pathogen in planta.


2020 ◽  
Author(s):  
Daniel F. Caddell ◽  
Katherine Louie ◽  
Benjamin Bowen ◽  
Julie A. Sievert ◽  
Joy Hollingsworth ◽  
...  

ABSTRACTInteractions between plants and their root-associated microbiome are important for determining host fitness during periods of stress. During drought, monoderm bacteria are more abundant in sorghum roots than in those of watered controls. Additionally, a reversion from monoderm to diderm dominance occurs in drought-stressed roots one week after rewatering. However, the mechanisms driving this rapid microbiome composition shift is currently unknown. To understand if changes in host metabolism are correlated with this shift, we employed 16S amplicon sequencing and metabolomics of root, rhizosphere, and soil at the peak of a preflowering drought and 24 hours after rewatering. The microbiomes of droughted roots, rhizospheres, and soils differed from watered controls, and shifts in bacterial composition were observed in root and rhizosphere 24 hours after rewatering, highlighting the rapid response of microbes to the cessation of drought. Next, we performed metabolomic profiling to identify putative drivers of this process. During drought, we observed a high abundance of abiotic stress response factors, including antioxidants, osmolytes, amino acids, and plant hormones. After rewatering, large shifts in metabolite abundances were observed in rhizosphere, whereas shifts in root and soil were subtle. In addition, pipecolic acid, a well-characterized systemic acquired resistance signalling compound, was enriched in roots and rhizosphere during drought. We found that exogenous application of pipecolic acid suppresses root growth via a systemic acquired resistance-independent mechanism. Collectively, these data provide a comprehensive characterization of metabolite shifts across three compartments during drought, and elucidate a potential role of pipecolic acid in the sorghum drought response.IMPORTANCEPlant-associated microbial communities shift in composition and contribute to host fitness during drought. In particular, Actinobacteria are enriched in plant roots and rhizosphere during drought. However, the mechanisms plants use to drive this shift are poorly understood. Here we apply a combination of bacterial and metabolite profiling in root, rhizosphere, and soil during drought and drought-recovery to investigate potential contributions of host metabolism towards shifts in bacterial composition. Our results demonstrate that drought alters metabolic profiles and that the response to rewatering differs between compartments; we identify drought-responsive metabolites that are highly correlated with Actinobacteria abundance. Furthermore, our study reports for the first time that pipecolic acid is a drought-enriched metabolite in sorghum roots. We demonstrate that exogenous application of pipecolic acid is able to provoke one of the classic drought responses in roots, root growth suppression, and that this activity functions independently from the systemic acquired resistance pathway.


Author(s):  
Eric C. Holmes ◽  
Yun-Chu Chen ◽  
Mary Beth Mudgett ◽  
Elizabeth S. Sattely

AbstractSystemic acquired resistance (SAR) is a mechanism that plants utilize to connect a local pathogen infection to global defense responses. N-hydroxy-pipecolic acid (NHP) and a glycosylated derivative are produced during SAR, yet their individual roles in the response have not yet been elucidated. Here we report that Arabidopsis thaliana UGT76B1 can generate glycosylated NHP (NHP-Glc) in vitro and when transiently expressed alongside Arabidopsis NHP biosynthetic genes in two Solanaceous plants. During infection, Arabidopsis ugt76b1 mutants do not accumulate NHP-Glc and accumulate less glycosylated salicylic acid (SA-Glc) than wild type plants. The metabolic changes in ugt76b1 mutant plants are accompanied by enhanced defense to the bacterial pathogen Pseudomonas syringae, suggesting that glycosylation of SAR molecules NHP and SA by UGT76B1 plays an important role in defense modulation. Transient expression of Arabidopsis UGT76B1 with the Arabidopsis NHP biosynthesis genes ALD1 and FMO1 in tomato increases NHP-Glc production and reduces NHP accumulation in local tissue, and abolishes the systemic resistance seen when expressing NHP-biosynthetic genes alone. These findings reveal that the glycosylation of NHP by UGT76B1 alters defense priming in systemic tissue and provide further evidence for the role of the NHP aglycone as the active metabolite in SAR signaling.


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