scholarly journals Insight into phytohormonal modulation of defense mechanisms to salt excess in a halophyte and a glycophyte from Asteraceae family

2021 ◽  
Author(s):  
Alina Wiszniewska ◽  
Aleksandra Koźmińska ◽  
Ewa Hanus-Fajerska ◽  
Kinga Dziurka ◽  
Michał Dziurka

Abstract Aims The aim of this study was to compare the efficiency of three defense mechanisms (ionic balance, osmotic adjustment and counteracting oxidative stress) under low, moderate and high soil salinity in two related species of contrasting tolerance to salinity: the halophyte Aster tripolium and the glycophyte Aster alpinus, and to elucidate their phytohormone-mediated regulation. Methods The phytohormonal profiling was performed to asses correlations between the pool of plant growth regulators and parameters depicting ionic homeostasis, osmotic adjustment and antioxidant system. Results Defense mechanisms in both species were based on accumulation/activity of distinct compounds (Na+ and K+ ions, antioxidants), but differences among species concerned particularly soluble carbohydrates and betaines. The halophyte accumulated mannitol, uronic acids and sucrose, while the glycophyte mostly glucose and proline-betaine. The halophyte responses also correlated with changes in the content of plant growth promoting PGRs, as well as jasmonates and benzoic acid. The glycophyte responses corresponded with changes in content of abscisic acid and ethylene precursor, as well as salicylic acid. Conclusions We provided evidence that benzoic acid rather than salicylic acid is involved in salt tolerance in the halophyte and elevated SA content may enhance vulnerability to salt excess. An important element of tolerance trait is also JA-GA network that influences the intensity of defense responses. This study uncovers new aspects of internal phytohormonal regulation of plant reaction to soil salinity and enables further insight into extremophyte biology.

2001 ◽  
Vol 125 (1) ◽  
pp. 318-328 ◽  
Author(s):  
Julie Chong ◽  
Marie-Agnès Pierrel ◽  
Rossitza Atanassova ◽  
Danièle Werck-Reichhart ◽  
Bernard Fritig ◽  
...  

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yi Li ◽  
Boon Huat Cheah ◽  
Yu-Fu Fang ◽  
Yun-Hung Kuang ◽  
Shau-Ching Lin ◽  
...  

Abstract Background Outbreaks of insect pests in paddy fields cause heavy losses in global rice yield annually, a threat projected to be aggravated by ongoing climate warming. Although significant progress has been made in the screening and cloning of insect resistance genes in rice germplasm and their introgression into modern cultivars, improved rice resistance is only effective against either chewing or phloem-feeding insects. Results In this study, the results from standard and modified seedbox screening, settlement preference and honeydew excretion tests consistently showed that Qingliu, a previously known leaffolder-resistant rice variety, is also moderately resistant to brown planthopper (BPH). High-throughput RNA sequencing showed a higher number of differentially expressed genes (DEGs) at the infestation site, with 2720 DEGs in leaves vs 181 DEGs in sheaths for leaffolder herbivory and 450 DEGs in sheaths vs 212 DEGs in leaves for BPH infestation. The leaf-specific transcriptome revealed that Qingliu responds to leaffolder feeding by activating jasmonic acid biosynthesis genes and genes regulating the shikimate and phenylpropanoid pathways that are essential for the biosynthesis of salicylic acid, melatonin, flavonoids and lignin defensive compounds. The sheath-specific transcriptome revealed that Qingliu responds to BPH infestation by inducing salicylic acid-responsive genes and those controlling cellular signaling cascades. Taken together these genes could play a role in triggering defense mechanisms such as cell wall modifications and cuticular wax formation. Conclusions This study highlighted the key defensive responses of a rarely observed rice variety Qingliu that has resistance to attacks by two different feeding guilds of herbivores. The leaffolders are leaf-feeder while the BPHs are phloem feeders, consequently Qingliu is considered to have dual resistance. Although the defense responses of Qingliu to both insect pest types appear largely dissimilar, the phenylpropanoid pathway (or more specifically phenylalanine ammonia-lyase genes) could be a convergent upstream pathway. However, this possibility requires further studies. This information is valuable for breeding programs aiming to generate broad spectrum insect resistance in rice cultivars.


2020 ◽  
Vol 71 (20) ◽  
pp. 6638-6654
Author(s):  
Sercan Pazarlar ◽  
Nedim Cetinkaya ◽  
Melike Bor ◽  
Recep Serdar Kara

Abstract N-acyl-homoserine lactones (AHLs), a well-described group of quorum sensing molecules, may modulate plant defense responses and plant growth. However, there is limited knowledge regarding the defense responses of non-model crops to AHLs and the mechanism of action responsible for the modulation of defense responses against microbial pathogens. In the present study, long-chain N-3-oxo-tetradecanoyl-l-homoserine lactone (oxo-C14-HSL) was shown to have a distinct potential to prime cucumber for enhanced defense responses against the biotrophic oomycete pathogen Pseudoperonospora cubensis and the hemibiotrophic bacterium Pseudomonas syringae pv. lachrymans. We provide evidence that AHL-mediated enhanced defense against downy mildew disease is based on cell wall reinforcement by lignin and callose deposition, the activation of defense-related enzymes (peroxidase, β-1,3-glucanase, phenylalanine ammonia-lyase), and the accumulation of reactive oxygen species (hydrogen peroxide, superoxide) and phenolic compounds. Quantitative analysis of salicylic acid and jasmonic acid, and transcriptional analysis of several of genes associated with these phytohormones, revealed that defense priming with oxo-C14-HSL is commonly regulated by the salicylic acid signaling pathway. We also show that treatment with short- (N-hexanoyl-l-homoserine lactone) and medium-chain (N-3-oxo-decanoyl-l-homoserine lactone) AHLs promoted primary root elongation and modified root architecture, respectively, resulting in enhanced plant growth.


Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1078
Author(s):  
Faisal Zulfiqar ◽  
Jianjun Chen ◽  
Patrick M. Finnegan ◽  
Adnan Younis ◽  
Muhammad Nafees ◽  
...  

Trehalose (Tre) and salicylic acid (SA) are increasingly used to mitigate drought stress in crop plants. In this study, a pot experiment was performed to study the influence of Tre and SA applied individually or in combination on the growth, photosynthesis, and antioxidant responses of sweet basil (Ocimum basilicum L.) exposed to drought stress. Basil plants were watered to 60% or 100% field capacity with or without treatment with 30 mM Tre and/or 1 mM SA. Drought negatively affected growth, physiological parameters, and antioxidant responses. Application of Tre and/or SA resulted in growth recovery, increased photosynthesis, and reduced oxidative stress. Application of Tre mitigated the detrimental effects of drought more than SA. Furthermore, co-application of Tre and SA largely eliminated the negative impact of drought by reducing oxidative stress through increased activities of antioxidant enzymes superoxide dismutase, peroxidase, and catalase, as well as the accumulation of the protective osmolytes proline and glycine betaine. Combined Tre and SA application improved water use efficiency and reduced the amount of malondialdehyde in drought-stressed plants. Our results suggested that combined application of Tre and SA may trigger defense mechanisms of sweet basil to better mitigate oxidative stress induced by drought stress, thereby improving plant growth.


2021 ◽  
Vol 12 ◽  
Author(s):  
Joon Hyuk Suh ◽  
Xixuan Tang ◽  
Yi Zhang ◽  
Frederick G. Gmitter ◽  
Yu Wang

There have been efforts to develop citrus cultivars that are tolerant of Huanglongbing (HLB), a catastrophic phloem-limited disease. Previous studies demonstrated that continuous plant growth with phloem regeneration is one of the major characteristics of HLB tolerance. In this study, the metabolic mechanisms of HLB tolerance in citrus were elucidated using a multiple pathway-targeted metabolomic approach. Comparative analysis of healthy and infected HLB-tolerant and HLB-sensitive mandarin cultivars (Citrus reticulata) revealed differentially expressed metabolic responses among different groups. Pathway enrichment analysis indicated aspartate and glutamate metabolism, purine metabolism, and biosynthesis of plant hormones were upregulated in the tolerant group, except salicylic acid signaling. Catabolic pathways linked to energy-yielding metabolism were also upregulated in the tolerant group. These metabolisms and pathways were interconnected with each other, unveiling a pivotal metabolic network associated with HLB tolerance. In the network, auxins and cytokinins, the plant hormones responsible for plant growth and phloem regeneration, were accumulated. In addition, purine metabolites serving as energy carriers and nitrogen sources of plants were increased. Only salicylic acid-related metabolites for plant defense responses were decreased in the tolerant group. Our findings may evidence the strategy of HLB-tolerant cultivars that sustain plant growth and phloem formation rather than displaying direct plant defense to overcome the disease.


Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1065
Author(s):  
Steven Criollo-Arteaga ◽  
Sofia Moya-Jimenez ◽  
Martin Jimenez-Meza ◽  
Victor Gonzalez-Vera ◽  
Jessica Gordon-Nunez ◽  
...  

Mineral nutrients are essential for plant growth and reproduction, yet only a few studies connect the nutritional status to plant innate immunity. The backbone of plant defense response is mainly controlled by two major hormones: salicylic acid (SA) and jasmonic acid (JA). This study investigated changes in the macronutrient concentration (deficiency/excess of nitrogen, phosphorus, potassium, magnesium, and sulfur) on the expression of PR1, a well-characterized marker in the SA-pathway, and PDF1.2 and LOX2 for the JA-pathway, analyzing plants carrying the promoter of each gene fused to GUS as a reporter. After histochemical GUS assays, we determined that PR1 gene was strongly activated in response to sulfur (S) deficiency. Using RT-PCR, we observed that the induction of PR1 depended on the function of Non-expressor of Pathogenesis-Related gene 1 (NPR1) and SA accumulation, as PR1 was not expressed in npr1-1 mutant and NahG plants under S-deprived conditions. Plants treated with different S-concentrations showed that total S-deprivation was required to induce SA-mediated defense responses. Additionally, bioassays revealed that S-deprived plants, induced resistance to the hemibiotrophic pathogen Pseudomonas syringae pv. DC3000 and increase susceptibility to the necrotrophic Botrytis cinerea. In conclusion, we observed a relationship between S and SA/JA-dependent defense mechanisms in Arabidopsis.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
ShiQiang Lin ◽  
ZhiJian Yang ◽  
BiFang Huang ◽  
ChuYun Bi ◽  
XiaoFang Huang ◽  
...  

AbstractThe Fusarium wilt disease caused by Fusarium oxysporum f. sp. batatas (Fob) is one of the devastating diseases of sweetpotato. However, the molecular mechanisms of sweetpotato response to Fob is poorly understood. In the present study, comparative quantitative proteomic analysis was conducted to investigate the defense mechanisms involved. Two sweetpotato cultivars with differential Fob infection responses were inoculated with Fob spore suspensions and quantitatively analyzed by Tandem Mass Tags (TMT). 2267 proteins were identified and 1897 of them were quantified. There were 817 proteins with quantitative ratios of 1.2-fold change between Fob-inoculated and mock-treated samples. Further, nine differentially expressed proteins were validated by Parallel Reaction Monitoring (PRM). According to Gene Ontology (GO) annotation information, the proteins functioned in molecular metabolism, cellular component formation, and biological processes. Interestingly, the results showed that sweetpotato resistant response to Fob infection included many proteins associated with signaling transduction, plant resistance, chitinase and subtilisin-like protease. The functions and possible roles of those proteins were discussed. The results provides first insight into molecular mechanisms involved in sweetpotato defense responses to Fob.


Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 962
Author(s):  
Maciej Jerzy Bernacki ◽  
Anna Rusaczonek ◽  
Weronika Czarnocka ◽  
Stanisław Karpiński

Salicylic acid (SA) is well known hormonal molecule involved in cell death regulation. In response to a broad range of environmental factors (e.g., high light, UV, pathogens attack), plants accumulate SA, which participates in cell death induction and spread in some foliar cells. LESION SIMULATING DISEASE 1 (LSD1) is one of the best-known cell death regulators in Arabidopsis thaliana. The lsd1 mutant, lacking functional LSD1 protein, accumulates SA and is conditionally susceptible to many biotic and abiotic stresses. In order to get more insight into the role of LSD1-dependent regulation of SA accumulation during cell death, we crossed the lsd1 with the sid2 mutant, caring mutation in ISOCHORISMATE SYNTHASE 1(ICS1) gene and having deregulated SA synthesis, and with plants expressing the bacterial nahG gene and thus decomposing SA to catechol. In response to UV A+B irradiation, the lsd1 mutant exhibited clear cell death phenotype, which was reversed in lsd1/sid2 and lsd1/NahG plants. The expression of PR-genes and the H2O2 content in UV-treated lsd1 were significantly higher when compared with the wild type. In contrast, lsd1/sid2 and lsd1/NahG plants demonstrated comparability with the wild-type level of PR-genes expression and H2O2. Our results demonstrate that SA accumulation is crucial for triggering cell death in lsd1, while the reduction of excessive SA accumulation may lead to a greater tolerance toward abiotic stress.


Rice ◽  
2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Kieu Thi Xuan Vo ◽  
Md Mizanor Rahman ◽  
Md Mustafizur Rahman ◽  
Kieu Thi Thuy Trinh ◽  
Sun Tae Kim ◽  
...  

AbstractBiotic stresses represent a serious threat to rice production to meet global food demand and thus pose a major challenge for scientists, who need to understand the intricate defense mechanisms. Proteomics and metabolomics studies have found global changes in proteins and metabolites during defense responses of rice exposed to biotic stressors, and also reported the production of specific secondary metabolites (SMs) in some cultivars that may vary depending on the type of biotic stress and the time at which the stress is imposed. The most common changes were seen in photosynthesis which is modified differently by rice plants to conserve energy, disrupt food supply for biotic stress agent, and initiate defense mechanisms or by biotic stressors to facilitate invasion and acquire nutrients, depending on their feeding style. Studies also provide evidence for the correlation between reactive oxygen species (ROS) and photorespiration and photosynthesis which can broaden our understanding on the balance of ROS production and scavenging in rice-pathogen interaction. Variation in the generation of phytohormones is also a key response exploited by rice and pathogens for their own benefit. Proteomics and metabolomics studies in resistant and susceptible rice cultivars upon pathogen attack have helped to identify the proteins and metabolites related to specific defense mechanisms, where choosing of an appropriate method to identify characterized or novel proteins and metabolites is essential, considering the outcomes of host-pathogen interactions. Despites the limitation in identifying the whole repertoire of responsive metabolites, some studies have shed light on functions of resistant-specific SMs. Lastly, we illustrate the potent metabolites responsible for resistance to different biotic stressors to provide valuable targets for further investigation and application.


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