Plant defenses induced by salicylic acid (SA) are vital for resistance against biotrophic pathogens. In basal and receptor-triggered immunity, SA accumulation is promoted by Enhanced Disease ...Susceptibility1 with its co-regulator Phytoalexin Deficient4 (EDS1/PAD4). Current models position EDS1/PAD4 upstream of SA but their functional relationship remains unclear.
In a genetic and transcriptomic analysis of Arabidopsis autoimmunity caused by constitutive or conditional EDS1/PAD4 overexpression, intrinsic EDS1/PAD4 signaling properties and their relation to SA were uncovered.
A core EDS1/PAD4 pathway works in parallel with SA in basal and effector-triggered bacterial immunity. It protects against disabled SA-regulated gene expression and pathogen resistance, and is distinct from a known SA-compensatory route involving MAPK signaling. Results help to explain previously identified EDS1/PAD4 regulated SA-dependent and SA-independent gene expression sectors.
Plants have evolved an alternative route for preserving SA-regulated defenses against pathogen or genetic perturbations. In a proposed signaling framework, EDS1 with PAD4, besides promoting SA biosynthesis, maintains important SA-related resistance programs, thereby increasing robustness of the innate immune system.
•Tezacaftor inhibits sphingolipid delta-4 desaturase (DEGS) in a concentration-dependent manner.•Irrespective of the genotype, treatment of human bronchial cells and hepatocytes with Tezacaftor ...results in accumulation of dihydroceramides.•A minor accumulation also occurs in-vivo, in mice brain, following five days oral treatment with the drug.
We recently demonstrated that 48 h exposure of primary human bronchial epithelial (hBE) cells, obtained from both CF (F508del homozygous) and non-CF subjects, to the triple drug combination Elexacaftor/Tezacaftor/Ivacaftor (ETI) results in a CFTR genotype-independent modulation of the de novo synthethic pathway of sphingolipids, with an accumulation of dihydroceramides (dHCer). Since dHCer are converted into ceramides (Cer) by the action of a delta-4 sphingolipid desaturase (DEGS) enzyme, we aimed to better understand this off-target effect of ETI (i.e., not related to CFTR rescue)
hBE cells, both F508del and wild-type, were cultured to create fully differentiated bronchial epithelia. We analyzed Cer and dHCer using an LC-MS based method previously developed by our lab. DEGS expression levels in differentiated hBE cells lysates were quantified by western blot analysis.
We demonstrated that 1) dHCer accumulate in hBE with time following prolonged ETI exposure, that 2) similar inhibition occurs in wild-type primary human hepatocytes and that 3) this does not result in an alteration of DEGS expression. We then proved that 4) ETI is a direct inhibitor of DEGS, that 5) Tezacaftor is the molecule responsible for this effect, that 6) the inhibition is concentration dependent. Finally, after repeated oral administration of ETI to naïve, non-CF, mice, we observed a slight accumulation of dHCer in the brain.
We believe that further investigations on Tezacaftor should be envisaged, particularly for the use of ETI during pregnancy, breastfeeding and in the early stages of development. DEGS dysfunction and dHCer accumulation causes impairment in the development of the nervous system, due to a derangement in myelin formation and maintenance.
Chloroplast immunity illuminated Littlejohn, George R.; Breen, Susan; Smirnoff, Nicholas ...
The New phytologist,
March 2021, Volume:
229, Issue:
6
Journal Article
Peer reviewed
Open access
Summary
The chloroplast has recently emerged as pivotal to co‐ordinating plant defence responses and as a target of plant pathogens. Beyond its central position in oxygenic photosynthesis and primary ...metabolism – key targets in the complex virulence strategies of diverse pathogens – the chloroplast integrates, decodes and responds to environmental signals. The capacity of chloroplasts to synthesize phytohormones and a diverse range of secondary metabolites, combined with retrograde and reactive oxygen signalling, provides exquisite flexibility to both perceive and respond to biotic stresses. These processes also represent a plethora of opportunities for pathogens to evolve strategies to directly or indirectly target ‘chloroplast immunity’. This review covers the contribution of the chloroplast to pathogen associated molecular pattern and effector triggered immunity as well as systemic acquired immunity. We address phytohormone modulation of immunity and surmise how chloroplast‐derived reactive oxygen species underpin chloroplast immunity through indirect evidence inferred from genetic modification of core chloroplast components and direct pathogen targeting of the chloroplast. We assess the impact of transcriptional reprogramming of nuclear‐encoded chloroplast genes during disease and defence and look at future research challenges.
An evolutionary transition in individuality (ETI) occurs when a previously independent organism becomes a lower level unit within a higher hierarchical level (for example, cells in an organism, ants ...in a colony). Using archaeological and historical accounts from the last 12 000 years, I empirically examine the proposition that human society increasingly functions as a higher hierarchical level within which individuals integrate as lower level units. I evaluate human societal development with respect to three criteria that together indicate complexity in biological systems and serve as an operationalization scheme for ETIs: size, inseparability and specialization. The
of the largest polity has increased seven orders of magnitude, from hundreds to billions.
became nearly complete since Mesopotamian city-states, following the first appearance of intricate
(division of labour).
within a polity has increased rapidly during the last few centuries, and particularly within the last few decades. In view of these results, I formulate the following hypothesis:
driven by socio-cultural-technological processes. This proposition requires a detailed theoretical basis and further empirical testing. I propose four predictions derived from the hypothesis that may be used to test it. This article is part of the theme issue 'Human socio-cultural evolution in light of evolutionary transitions'.
Plant immune networks Ngou, Bruno Pok Man; Jones, Jonathan D.G.; Ding, Pingtao
Trends in plant science,
March 2022, 2022-03-00, 20220301, Volume:
27, Issue:
3
Journal Article
Peer reviewed
Open access
Plants have both cell-surface and intracellular receptors to recognize diverse self- and non-self molecules. Cell-surface pattern recognition receptors (PRRs) recognize extracellular ...pathogen-/damage-derived molecules or apoplastic pathogen-derived effectors. Intracellular nucleotide-binding leucine-rich repeat proteins (NLRs) recognize pathogen effectors. Activation of both PRRs and NLRs elevates defense gene expression and accumulation of the phytohormone salicylic acid (SA), which results in SA-dependent transcriptional reprogramming. These receptors, together with their coreceptors, form networks to mediate downstream immune responses. In addition, cell-surface and intracellular immune systems are interdependent and function synergistically to provide robust resistance against pathogens. Here, we summarize the interactions between these immune systems and attempt to provide a holistic picture of plant immune networks. We highlight current challenges and discuss potential new research directions.
Plant immunity is activated by PAMPs, effectors, and further enhanced by elevated SA, which are mediated by PRRs, NLRs, and SA receptors (NPR proteins), respectively.PRRs, NLRs, and NPR proteins interact genetically to mediate immune signals and activate robust immune outputs.Models are being elaborated for the crosstalk between PRRs, NLRs, and SA signaling.Different immune systems interact with each other both locally and systemically.
The conserved lipase-like protein EDS1 transduces signals from pathogen-activated intracellular nucleotide-binding leucine-rich repeat (NLR) receptors to transcriptional defences and host cell death. ...In this pivotal NLR signalling role, EDS1 works as a heterodimer with each of its partners, SAG101 and PAD4. Different properties of EDS1-SAG101 and EDS1-PAD4 complexes and functional relationships to sensor and helper NLRs have emerged. EDS1-SAG101 dimers confer effector-triggered immunity mediated by intracellular TNL receptors. In contrast, EDS1-PAD4 dimers have a broader role promoting basal immune responses that can be initiated inside cells by TNL- or CNL-type NLRs, and at the cell surface by LRR-receptor proteins. Characterizing the essential elements of these two EDS1 modules will help to connect intracellular and surface receptor signalling networks in the plant immune system.
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Summary
Abiotic and biotic environments influence a myriad of plant‐related processes, including growth, development, and the establishment and maintenance of interaction(s) with microbes. In the ...case of the latter, elevated temperature has been shown to be a key factor that underpins host resistance and pathogen virulence.
In this study, we elucidate a role for Arabidopsis NON‐RACE‐SPECIFIC DISEASE RESISTANCE1 (NDR1) by exploiting effector‐triggered immunity to define the regulation of plant host immunity in response to both pathogen infection and elevated temperature.
We generated time‐series RNA sequencing data of WT Col‐0, an NDR1 overexpression line, and ndr1 and ics1‐2 mutant plants under elevated temperature. Not surprisingly, the NDR1‐overexpression line showed genotype‐specific gene expression changes related to defense response and immune system function.
The results described herein support a role for NDR1 in maintaining cell signaling during simultaneous exposure to elevated temperature and avirulent pathogen stressors.
Ca2+ signals in plant immunity Köster, Philipp; DeFalco, Thomas A; Zipfel, Cyril
The EMBO journal,
14 June 2022, Volume:
41, Issue:
12
Journal Article
Peer reviewed
Open access
Calcium ions function as a key second messenger ion in eukaryotes. Spatially and temporally defined cytoplasmic Ca2+ signals are shaped through the concerted activity of ion channels, exchangers, and ...pumps in response to diverse stimuli; these signals are then decoded through the activity of Ca2+‐binding sensor proteins. In plants, Ca2+ signaling is central to both pattern‐ and effector‐triggered immunity, with the generation of characteristic cytoplasmic Ca2+ elevations in response to potential pathogens being common to both. However, despite their importance, and a long history of scientific interest, the transport proteins that shape Ca2+ signals and their integration remain poorly characterized. Here, we discuss recent work that has both shed light on and deepened the mysteries of Ca2+ signaling in plant immunity.
This review summarizes how calcium ions, and the proteins which transport them, are integrated into plant immune responses.
Plant resistance proteins provide race-specific immunity through the recognition of pathogen effectors. The resistance genes I, I-2 and I-3 have been incorporated into cultivated tomato (Solanum ...lycopersicum) from wild tomato species to confer resistance against Fusarium oxysporum f. sp. lycopersici (Fol) races 1, 2 and 3, respectively. Although the Fol effectors corresponding to these resistance genes have all been identified, only the I-2 resistance gene has been isolated from tomato.
To isolate the I-3 resistance gene, we employed a map-based cloning approach and used transgenic complementation to test candidate genes for resistance to Fol race 3.
Here, we describe the fine mapping and sequencing of genes at the I-3 locus, which revealed a family of S-receptor-like kinase (SRLK) genes. Transgenic tomato lines were generated with three of these SRLK genes and one was found to confer Avr3-dependent resistance to Fol race 3, confirming it to be I-3.
The finding that I-3 encodes an SRLK reveals a new pathway for Fol resistance and a new class of resistance genes, of which Pi-d2 from rice is also a member. The identification of I-3 also allows the investigation of the complex effector–resistance protein interaction involving Avr1-mediated suppression of I-2- and I-3-dependent resistance in tomato.
The World Energy Council releases the Energy Trilemma Index (ETI) report annually primarily to assess the energy performance of countries worldwide. Nevertheless, the varying preferences of the ...dimensions in the ETI between the countries are debatable. The objective of this study is weight allocation therefore this study presents two-fold contribution to comprehensively formulate all possible preferences under the interval assessment outcomes by employing the interval decision matrix followed by the Principal Component Analysis (PCA) to assess the national energy performance of top ten countries for the year 2015. Unlike the conventional methods, the significant advantage of PCA for index construction is that it does not allocate ad-hoc and subjective weights to different indicators. The obtained results were demonstrated by measurement of top ten countries energy performance based on ETI of 2015. Through the development of Energy Development Index, Norway was determined as the highest performing country among the top ten countries. This does not coincide with 2015's ETI which regarded Switzerland as the best performing country. Hence, the ranks are arguable. Further results reveals that there are considerable differences in the values of indicators among all countries. The obtained outcome is expected to aid the policy makers to understand the contribution of different indicators.
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