scholarly journals Chitosan Oligosaccharide Induces Resistance to Pseudomonas syringae pv. tomato DC3000 in Arabidopsis thaliana by Activating Both Salicylic Acid– and Jasmonic Acid–Mediated Pathways

2018 ◽  
Vol 31 (12) ◽  
pp. 1271-1279 ◽  
Author(s):  
Xiaochen Jia ◽  
Haihong Zeng ◽  
Wenxia Wang ◽  
Fuyun Zhang ◽  
Heng Yin

Chitosan oligosaccharide (COS) is an effective plant immunity elicitor; however, its induction mechanism in plants is complex and needs further investigation. In this study, the Arabidopsis–Pseudomonas syringae pv. tomato DC3000 (hereafter called DC3000) interaction was used to investigate the induction effect and the underlying mechanisms of COS. COS is effective in inducing resistance to DC3000 in Arabidopsis, and our results demonstrate that treatment with COS 3 days before DC3000 inoculation provided the most effective resistance. Disease severity in jar1 (jasmonic acid [JA]-deficient mutant), NahG, and sid2 (salicylic acid [SA]-deficient mutants) suggest both the SA and JA pathways are required for the Arabidopsis response to DC3000. COS pretreatment induced resistance in wild type (WT), jar1, and also, although to a lesser degree, in NahG and sid2 plants, implying that the SA and JA pathways play redundant roles in COS-induced resistance to DC3000. In COS-pretreated plants, expression of genes related to the SA pathway (PR1, PR2, and PR5) and SA content increased in both WT and jar1. Moreover, expression of genes related to the JA pathway (PDF1.2 and VSP2) and JA content both increased in WT and NahG. In conclusion, COS induces resistance to DC3000 in Arabidopsis by activating both SA- and JA-mediated pathways, although SA and JA pathways play redundant roles in this COS-induced resistance.

2014 ◽  
Vol 104 (12) ◽  
pp. 1283-1288 ◽  
Author(s):  
Dominik K. Großkinsky ◽  
Eric van der Graaff ◽  
Thomas Roitsch

Phytohormones are known as essential regulators of plant defenses, with ethylene, jasmonic acid, and salicylic acid as the central immunity backbone, while other phytohormones have been demonstrated to interact with this. Only recently, a function of the classic phytohormone cytokinin in plant immunity has been described in Arabidopsis, rice, and tobacco. Although interactions of cytokinins with salicylic acid and auxin have been indicated, the complete network of cytokinin interactions with other immunity-relevant phytohormones is not yet understood. Therefore, we studied the interaction of kinetin and abscisic acid as a negative regulator of plant immunity to modulate resistance in tobacco against Pseudomonas syringae. By analyzing infection symptoms, pathogen proliferation, and accumulation of the phytoalexin scopoletin as a key mediator of kinetin-induced resistance in tobacco, antagonistic interaction of these phytohormones in plant immunity was identified. Kinetin reduced abscisic acid levels in tobacco, while increased abscisic acid levels by exogenous application or inhibition of abscisic acid catabolism by diniconazole neutralized kinetin-induced resistance. Based on these results, we conclude that reduction of abscisic acid levels by enhanced abscisic acid catabolism strongly contributes to cytokinin-mediated resistance effects. Thus, the identified cytokinin–abscisic acid antagonism is a novel regulatory mechanism in plant immunity.


2019 ◽  
Vol 60 (7) ◽  
pp. 1536-1555 ◽  
Author(s):  
Ronny V�lz ◽  
Soon-Kap Kim ◽  
Jianing Mi ◽  
Kiruthiga G Mariappan ◽  
Anna Siodmak ◽  
...  

Abstract INDETERMINATE DOMAIN (IDD)/BIRD proteins belong to a highly conserved plant-specific group of transcription factors with dedicated functions in plant physiology and development. Here, we took advantage of the chimeric repressor gene-silencing technology (CRES-T, SRDX) to widen our view on the role of IDD4/IMPERIAL EAGLE and IDD family members in plant immunity. The hypomorphic idd4SRDX lines are compromised in growth and show a robust autoimmune phenotype. Hormonal measurements revealed the concomitant accumulation of salicylic acid and jasmonic acid suggesting that IDDs are involved in regulating the metabolism of these biotic stress hormones. The analysis of immunity-pathways showed enhanced activation of immune MAP kinase-signaling pathways, the accumulation of hydrogen peroxide and spontaneous programmed cell death. The transcriptome of nonelicited idd4SRDX lines can be aligned to approximately 40% of differentially expressed genes (DEGs) in flg22-treated wild-type plants. The pattern of DEGs implies IDDs as pivotal repressors of flg22-dependent gene induction. Infection experiments showed the increased resistance of idd4SRDX lines to Pseudomonas syringae and Botrytis cinerea implying a function of IDDs in defense adaptation to hemibiotrophs and necrotrophs. Genome-wide IDD4 DNA-binding studies (DAP-SEQ) combined with DEG analysis of idd4SRDX lines identified IDD4-regulated functional gene clusters that contribute to plant growth and development. In summary, we discovered that the expression of idd4SRDX activates a wide range of defense-related traits opening up the possibility to apply idd4SRDX as a powerful tool to stimulate innate immunity in engineered crops.


2007 ◽  
Vol 20 (8) ◽  
pp. 955-965 ◽  
Author(s):  
Srinivasa Rao Uppalapati ◽  
Yasuhiro Ishiga ◽  
Tamding Wangdi ◽  
Barbara N. Kunkel ◽  
Ajith Anand ◽  
...  

The roles of the phytotoxin coronatine (COR) and salicylic acid (SA)-mediated defenses in the interaction of Pseudomonas syringae pv. tomato DC3000 and tomato (Solanum lycopersicum) were investigated. Unlike findings reported for Arabidopsis thaliana, DC3000 mutants impaired for production of COR or one of its components, coronafacic acid (CFA) or coronamic acid (CMA), induced distinctly different disease lesion phenotypes in tomato. Tomato plants inoculated with the CFA- CMA- mutant DB29 showed elevated transcript levels of SlICS, which encodes isochorismate synthase, an enzyme involved in SA biosynthesis in S. lycopersicum. Furthermore, expression of genes encoding SA-mediated defense proteins were elevated in DB29-inoculated plants compared with plants inoculated with DC3000, suggesting that COR suppresses SlICS-mediated SA responses. Sequence analysis of SlICS revealed that it encodes a protein that is 55 and 59.6% identical to the A. thaliana ICS-encoded proteins AtICS1 and AtICS2, respectively. Tomato plants silenced for SlICS were hypersusceptible to DC3000 and accumulated lower levels of SA after infection with DC3000 compared with inoculated wild-type tomato plants. Unlike what has been shown for A. thaliana, the COR- mutant DB29 was impaired for persistence in SlICS-silenced tomato plants; thus, COR has additional roles in virulence that are SA independent and important in the latter stages of disease development. In summary, the infection assays, metabolic profiling, and gene expression results described in this study indicate that the intact COR molecule is required for both suppression of SA-mediated defense responses and full disease symptom development in tomato.


2019 ◽  
Vol 14 (4) ◽  
pp. e1581560 ◽  
Author(s):  
Rocío Escobar Bravo ◽  
Gang Chen ◽  
Katharina Grosser ◽  
Nicole M. Van Dam ◽  
Kirsten A. Leiss ◽  
...  

Plants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 624 ◽  
Author(s):  
Vicente Montejano-Ramírez ◽  
Ernesto García-Pineda ◽  
Eduardo Valencia-Cantero

Plants face a variety of biotic and abiotic stresses including attack by microbial phytopathogens and nutrient deficiencies. Some bacterial volatile organic compounds (VOCs) activate defense and iron-deficiency responses in plants. To establish a relationship between defense and iron deficiency through VOCs, we identified key genes in the defense and iron-deprivation responses of the legume model Medicago truncatula and evaluated the effect of the rhizobacterial VOC N,N-dimethylhexadecylamine (DMHDA) on the gene expression in these pathways by RT-qPCR. DMHDA increased M. truncatula growth 1.5-fold under both iron-sufficient and iron-deficient conditions compared with untreated plants, whereas salicylic acid and jasmonic acid decreased growth. Iron-deficiency induced iron uptake and defense gene expression. Moreover, the effect was greater in combination with DMHDA. Salicylic acid, Pseudomonas syringae, jasmonic acid, and Botrytis cinerea had inhibitory effects on growth and iron response gene expression but activated defense genes. Taken together, our results showed that the VOC DMHDA activates defense and iron-deprivation pathways while inducing a growth promoting effect unlike conventional phytohormones, highlighting that DMHDA does not mimic jasmonic acid but induces an alternative pathway. This is a novel aspect in the complex interactions between biotic and abiotic stresses.


2019 ◽  
Vol 109 (7) ◽  
pp. 1102-1114 ◽  
Author(s):  
Qiuying Wang ◽  
Xiuling Chen ◽  
Xinfeng Chai ◽  
Dongqi Xue ◽  
Wei Zheng ◽  
...  

Tomato gray mold disease caused by Botrytis cinerea is a serious disease that threatens tomato production around the world. Clonostachys rosea has been used successfully as a biocontrol agent against divergent plant pathogens, including B. cinerea. To understand the signal transduction pathway of C. rosea-induced resistance to tomato gray mold disease, the effects of C. rosea on gray mold tomato leaves along with changes in the activities of three defense enzymes (phenylalanine ammonialyase [PAL], polyphenol oxidase [PPO], and catalase [CAT]), second messengers (nitric oxide [NO], hydrogen peroxide [H2O2], and superoxide anion radical [O2−]), and stress-related genes (mitogen-activated protein kinase [MAPK], WRKY, Lexyl2, and atpA) in four different hormone-deficient (jasmonic acid [JA], ethylene [ET], salicylic acid [SA], and gibberellin) tomato mutants were investigated. The results revealed that C. rosea significantly inhibited the growth of mycelia and spore germination of B. cinerea. Furthermore, it reduced the incidence of gray mold disease, induced higher levels of PAL and PPO, and induced lower levels of CAT activities in tomato leaves. Moreover, it also increased NO, H2O2, and O2− levels and the gene expression levels of WRKY, MAPK, atpA, and Lexyl2. The incidence of gray mold disease in four hormone-deficient mutants was higher than that in the corresponding wild-type tomato plants. Among all of these hormone-deficient tomato mutants, JA had the most significant effect in regulating the different signal molecules. Additional study suggested that JA upregulated the expression of Lexyl2, MAPK, and WRKY but downregulated atpA. Furthermore, JA also enhanced the activity of PAL, PPO, and CAT and the production of NO and H2O2. SA downregulated CAT and PAL, whereas ET upregulated PAL but downregulated CAT. This study is of significance in understanding the regulatory pathways and biocontrol mechanism of C. rosea against B. cinerea.


2000 ◽  
Vol 12 (11) ◽  
pp. 2175 ◽  
Author(s):  
Joseph D. Clarke ◽  
Sigrid M. Volko ◽  
Heidi Ledford ◽  
Frederick M. Ausubel ◽  
Xinnian Dong

Plants ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 136 ◽  
Author(s):  
Loredana Scalschi ◽  
Eugenio Llorens ◽  
Pilar García-Agustín ◽  
Begonya Vicedo

The jasmonic acid pathway has been considered as the backbone of the response against necrotrophic pathogens. However, a hemi-biotrophic pathogen, such as Pseudomonas syringae, has taken advantage of the crosstalk between the different plant hormones in order to manipulate the responses for its own interest. Despite that, the way in which Pseudomonas syringae releases coronatine to activate jasmonic acid-derived responses and block the activation of salicylic acid-mediated responses is widely known. However, the implication of the jasmonic intermediates in the plant-Pseudomonas interaction is not studied yet. In this work, we analyzed the response of both, plant and bacteria using SiOPR3 tomato plants. Interestingly, SiOPR3 plants are more resistant to infection with Pseudomonas. The gene expression of bacteria showed that, in SiOPR3 plants, the activation of pathogenicity is repressed in comparison to wild type plants, suggesting that the jasmonic acid pathway might play a role in the pathogenicity of the bacteria. Moreover, treatments with JA restore the susceptibility as well as activate the expression of bacterial pathogenicity genes. The observed results suggest that a complete jasmonic acid pathway is necessary for the susceptibility of tomato plants to Pseudomonas syringae.


2009 ◽  
Vol 22 (9) ◽  
pp. 1069-1080 ◽  
Author(s):  
Ming Guo ◽  
Fang Tian ◽  
Yashitola Wamboldt ◽  
James R. Alfano

The Pseudomonas syringae type III protein secretion system (T3SS) and the type III effectors it injects into plant cells are required for plant pathogenicity and the ability to elicit a hypersensitive response (HR). The HR is a programmed cell death that is associated with effector-triggered immunity (ETI). A primary function of P. syringae type III effectors appears to be the suppression of ETI and pathogen-associated molecular pattern–triggered immunity (PTI), which is induced by conserved molecules on microorganisms. We reported that seven type III effectors from P. syringae pv. tomato DC3000 were capable of suppressing an HR induced by P. fluorescens(pHIR11) and have now tested 35 DC3000 type III effectors in this assay, finding that the majority of them can suppress the HR induced by HopA1. One newly identified type III effector with particularly strong HR suppression activity was HopS2. We used the pHIR11 derivative pLN1965, which lacks hopA1, in related assays and found that a subset of the type III effectors that suppressed HopA1-induced ETI also suppressed an ETI response induced by AvrRpm1 in Arabidopsis thaliana. A. thaliana plants expressing either HopAO1 or HopF2, two type III effectors that suppressed the HopA1-induced HR, were reduced in the flagellin-induced PTI response as well as PTI induced by other PAMPs and allowed enhanced in planta growth of P. syringae. Collectively, our results suggest that the majority of DC3000 type III effectors can suppress plant immunity. Additionally, the construct pLN1965 will likely be a useful tool in determining whether other type III effectors or effectors from other types of pathogens can suppress either ETI, PTI, or both.


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