Oxidative Burst in Alfalfa-Sinorhizobium meliloti Symbiotic Interaction

Reactive oxygen species are produced as an early event in plant defense response against avirulent pathogens. We show here that alfalfa responds to infection with Sinorhizobium meliloti by production of superoxide and hydrogen peroxide. This similarity in the early response to infection by pathogenic and symbiotic bacteria addresses the question of which mechanism rhizobia use to counteract the plant defense response.

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Sinorhizobium meliloti nifA gene exerts a pleiotropic effect on nodulation through the enhanced plant defense response

Chinese Science Bulletin ◽

10.1007/s11434-007-0427-2 ◽

2007 ◽

Vol 52 (21) ◽

pp. 2925-2929 ◽

Cited By ~ 1

Author(s):

XiaoTao Chen ◽

HuaSong Zou ◽

ZhenHua Yao ◽

HaiPing Cheng ◽

XiaoMi Dai ◽

...

Keyword(s):

Plant Defense ◽

Defense Response ◽

Sinorhizobium Meliloti ◽

Pleiotropic Effect ◽

Plant Defense Response ◽

Nifa Gene

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Deletion of the SACPD-C Locus Alters the Symbiotic Relationship Between Bradyrhizobium japonicum USDA110 and Soybean, Resulting in Elicitation of Plant Defense Response and Nodulation Defects

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-08-16-0173-r ◽

2016 ◽

Vol 29 (11) ◽

pp. 862-877 ◽

Cited By ~ 6

Author(s):

Hari B. Krishnan ◽

Alaa A. Alaswad ◽

Nathan W. Oehrle ◽

Jason D. Gillman

Keyword(s):

Plant Defense ◽

Defense Response ◽

Acyl Carrier Protein ◽

Defense Responses ◽

Nodule Development ◽

Plant Defense Response ◽

Wild Type ◽

Two Dimensional Gel Electrophoresis ◽

Symbiotic Associations ◽

Soybean Nodule

Legumes form symbiotic associations with soil-dwelling bacteria collectively called rhizobia. This association results in the formation of nodules, unique plant-derived organs, within which the rhizobia are housed. Rhizobia-encoded nitrogenase facilitates the conversion of atmospheric nitrogen into ammonia, which is utilized by the plants for its growth and development. Fatty acids have been shown to play an important role in root nodule symbiosis. In this study, we have investigated the role of stearoyl-acyl carrier protein desaturase isoform C (SACPD-C), a soybean enzyme that catalyzes the conversion of stearic acid into oleic acid, which is expressed in developing seeds and in nitrogen-fixing nodules. In-depth cytological investigation of nodule development in sacpd-c mutant lines M25 and MM106 revealed gross anatomical alteration in the sacpd-c mutants. Transmission electron microscopy observations revealed ultrastructural alterations in the sacpd-c mutants that are typically associated with plant defense response to pathogens. In nodules of two sacpd-c mutants, the combined jasmonic acid (JA) species (JA and the isoleucine conjugate of JA) were found to be reduced and 12-oxophytodienoic acid (OPDA) levels were significantly higher relative to wild-type lines. Salicylic acid levels were not significantly different between genotypes, which is divergent from previous studies of sacpd mutant studies on vegetative tissues. Soybean nodule phytohormone profiles were very divergent from those of roots, and root profiles were found to be almost identical between mutant and wild-type genotypes. The activities of antioxidant enzymes, ascorbate peroxidase, and superoxide dismutase were also found to be higher in nodules of sacpd-c mutants. PR-1 gene expression was extremely elevated in M25 and MM106, while the expression of nitrogenase was significantly reduced in these sacpd-c mutants, compared with the parent ‘Bay’. Two-dimensional gel electrophoresis and matrix-assisted laser desorption-ionization time of flight mass spectrometry analyses confirmed sacpd-c mutants also accumulated higher amounts of pathogenesis-related proteins in the nodules. Our study establishes a major role for SACPD-C activity as essential for proper maintenance of soybean nodule morphology and physiology and indicates that OPDA signaling is likely to be involved in attenuation of nodule biotic defense responses.

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Activation of the JAK-STAT pathway by reactive oxygen species

AJP Cell Physiology ◽

10.1152/ajpcell.1998.275.6.c1640 ◽

1998 ◽

Vol 275 (6) ◽

pp. C1640-C1652 ◽

Cited By ~ 364

Author(s):

Amy R. Simon ◽

Usha Rai ◽

Barry L. Fanburg ◽

Brent H. Cochran

Keyword(s):

Reactive Oxygen Species ◽

Mammalian Cells ◽

Reactive Oxygen ◽

Buthionine Sulfoximine ◽

Early Response ◽

Carcinoma Cells ◽

Oxygen Species ◽

Intracellular Ros ◽

Diphenylene Iodonium ◽

Stat Pathway

Reactive oxygen species (ROS) play an important role in the pathogenesis of many human diseases, including the acute respiratory distress syndrome, Parkinson’s disease, pulmonary fibrosis, and Alzheimer’s disease. In mammalian cells, several genes known to be induced during the immediate early response to growth factors, including the protooncogenes c- fos and c- myc, have also been shown to be induced by ROS. We show that members of the STAT family of transcription factors, including STAT1 and STAT3, are activated in fibroblasts and A-431 carcinoma cells in response to H2O2. This activation occurs within 5 min, can be inhibited by antioxidants, and does not require protein synthesis. STAT activation in these cell lines is oxidant specific and does not occur in response to superoxide- or nitric oxide-generating stimuli. Buthionine sulfoximine, which depletes intracellular glutathione, also activates the STAT pathway. Moreover, H2O2stimulates the activity of the known STAT kinases JAK2 and TYK2. Activation of STATs by platelet-derived growth factor (PDGF) is significantly inhibited by N-acetyl-l-cysteine and diphenylene iodonium, indicating that ROS production contributes to STAT activation in response to PDGF. These findings indicate that the JAK-STAT pathway responds to intracellular ROS and that PDGF uses ROS as a second messenger to regulate STAT activation.

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