scholarly journals Fitness Costs of Mutations Affecting the Systemic Acquired Resistance Pathway in Arabidopsis thaliana

Genetics ◽  
2004 ◽  
Vol 168 (4) ◽  
pp. 2197-2206 ◽  
Author(s):  
Andrew J. Heidel ◽  
Joseph D. Clarke ◽  
Janis Antonovics ◽  
Xinnian Dong
Keyword(s):  
Arabidopsis Thaliana ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Fitness Costs ◽  
Resistance Pathway

scholarly journals Overexpression of a Rice NPR1 Homolog Leads to Constitutive Activation of Defense Response and Hypersensitivity to Light

2005 ◽  
Vol 18 (6) ◽  
pp. 511-520 ◽  
Author(s):  
Mawsheng Chern ◽  
Heather A. Fitzgerald ◽  
Patrick E. Canlas ◽  
Duroy A. Navarre ◽  
Pamela C. Ronald
Keyword(s):  
Systemic Acquired Resistance ◽  
Environmental Changes ◽  
Acquired Resistance ◽  
Northern Analysis ◽  
Wild Type ◽  
Defense Genes ◽  
Isolation And Characterization ◽  
Broad Spectrum Resistance ◽  
Resistance Pathway

Arabidopsis NPR1/NIM1 is a key regulator of systemic acquired resistance (SAR), which confers lasting broad-spectrum resistance. Previous reports indicate that rice has a disease-resistance pathway similar to the Arabidopsis SAR pathway. Here we report the isolation and characterization of a rice NPR1 homologue (NH1). Transgenic rice plants overexpressing NH1 (NH1ox) acquire high levels of resistance to Xanthomonas oryzae pv. oryzae. The resistance phenotype is heritable and correlates with the presence of the transgene and reduced bacterial growth. Northern analysis shows that NH1ox rice spontaneously activates defense genes, contrasting with NPR1-overexpressing Arabidopsis, where defense genes are not activated until induction. Wild-type NH1, but not a point mutant corresponding to npr1-1, interacts strongly with the rice transcription factor rTGA2.2 in yeast two-hybrid. Greenhouse-grown NH1ox plants develop lesion-mimic spots on leaves at preflowering stage although no other developmental effects are observed. However, when grown in growth chambers (GCs) under low light, NH1ox plants are dwarfed, indicating elevated sensitivity to light. The GC-grown NH1ox plants show much higher salicylic acid (SA) levels than the wild type, whereas greenhouse-grown NH1ox plants contain lower SA. These results indicate that NH1 may be involved in the regulation of SA in response to environmental changes.

scholarly journals Drought shifts sorghum root metabolite and microbiome profiles and enriches the stress response factor pipecolic acid

2020 ◽  
Author(s):  
Daniel F. Caddell ◽  
Katherine Louie ◽  
Benjamin Bowen ◽  
Julie A. Sievert ◽  
Joy Hollingsworth ◽  
...  
Keyword(s):  
Stress Response ◽  
Root Growth ◽  
Systemic Acquired Resistance ◽  
Acquired Resistance ◽  
Pipecolic Acid ◽  
Bacterial Composition ◽  
Host Fitness ◽  
Exogenous Application ◽  
Resistance Pathway ◽  
Host Metabolism

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.

scholarly journals Constitutive cyclic GMP accumulation in Arabidopsis thaliana compromises systemic acquired resistance induced by an avirulent pathogen by modulating local signals

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Jamshaid Hussain ◽  
Jian Chen ◽  
Vittoria Locato ◽  
Wilma Sabetta ◽  
Smrutisanjita Behera ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Large Scale ◽  
Systemic Acquired Resistance ◽  
Soluble Guanylate Cyclase ◽  
Acquired Resistance ◽  
Plant Defence ◽  
Redox System ◽  
Wild Type ◽  
Transgenic Lines ◽  
Defence Responses

Abstract The infection of Arabidopsis thaliana plants with avirulent pathogens causes the accumulation of cGMP with a biphasic profile downstream of nitric oxide signalling. However, plant enzymes that modulate cGMP levels have yet to be identified, so we generated transgenic A. thaliana plants expressing the rat soluble guanylate cyclase (GC) to increase genetically the level of cGMP and to study the function of cGMP in plant defence responses. Once confirmed that cGMP levels were higher in the GC transgenic lines than in wild-type controls, the GC transgenic plants were then challenged with bacterial pathogens and their defence responses were characterized. Although local resistance was similar in the GC transgenic and wild-type lines, differences in the redox state suggested potential cross-talk between cGMP and the glutathione redox system. Furthermore, large-scale transcriptomic and proteomic analysis highlighted the significant modulation of both gene expression and protein abundance at the infection site, inhibiting the establishment of systemic acquired resistance. Our data indicate that cGMP plays a key role in local responses controlling the induction of systemic acquired resistance in plants challenged with avirulent pathogens.

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