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.
In the field, plants constantly face a plethora of abiotic and biotic stresses that can impart detrimental effects on plants. In response to multiple stresses, plants can rapidly reprogram their ...transcriptome through a tightly regulated and highly dynamic regulatory network where WRKY transcription factors can act as activators or repressors. WRKY transcription factors have diverse biological functions in plants, but most notably are key players in plant responses to biotic and abiotic stresses. In tomato there are 83
genes identified. Here we review recent progress on functions of these tomato
genes and their homologs in other plant species, such as Arabidopsis and rice, with a special focus on their involvement in responses to abiotic and biotic stresses. In particular, we highlight
genes that play a role in plant responses to a combination of abiotic and biotic stresses.
This study examines the relationship between energy security, energy equity, and environmental sustainability from the perspective of economic growth and CO2 emissions. For this purpose, this study ...utilizes the energy trilemma index (ETI) 2018 of the World Energy Council (WEC) to measure, evaluate and assess the energy efficiency of the top ten best-performing countries around the world. This study formulates an interval decision matrix to apply Principal Components Analysis (PCA) by reducing a large set into a small set of underlying variables with comprehensive information. Finally, this study uses the Fuzzy-TOPSIS method to determine the comprehensive ranks of all countries. This study shows that Denmark holds overall first rank in energy efficiency with a score of one in energy security, eleven in energy equity, and seventeen in environmental sustainability. In contrast, Germany has dominated all top ten performers by energy and environmental progress, which cannot be shirker within the UK's social progress concept. Thus, with ceteris paribus, a higher energy price will indicate a higher degree of scarcity of energy sources, encouraging working for cheaper and renewable alternatives and ultimately influencing the energy supply side. Carbon valuation can reduce greenhouse emissions by paying the extra dollar to the enterprise for less emission. It will lead to changing energy consumption structures and make it a cleaner choice for profit maximization.
•Energy Trilemma Index of World Energy Council 2018 has been evaluated.•Fuzzy-TOPSIS and Principal Components Analysis applied to 10 best-performing countries.•Denmark led in energy efficiency while Germany dominated in environmental progress.•A higher energy price will indicate a higher degree of scarcity of energy sources.•CO2 valuation can reduce emissions by paying extra $ to enterprise for less emission.
•Nod factors that elicit legume nodule organogenesis also suppress plant immunity.•The rhizobial type III secretion system (T3SS) can influence host range.•Resistance gene-mediated immunity can ...impact upon rhizobial host range.•Management of host defenses is also important for the maintenance of symbiosis.•The plant growth environment can impact upon plant defense and symbiosis.
New research results have significantly revised our understanding of the rhizobium–legume infection process. For example, Nod factors (NFs), previously thought to be absolutely essential for this symbiosis, were shown to be dispensable under particular conditions. Similarly, an NF receptor, previously considered to be solely involved in symbiosis, was shown to function during plant pathogen infections. Indeed, there is a growing realization that plant innate immunity is a crucial component in the establishment and maintenance of symbiosis. We review here the factors involved in the suppression of plant immunity during rhizobium–legume symbiosis, and we attempt to place this information into context with the most recent and sometimes surprising research results.
Plants use surface resident and intracellular immune receptors to provide robust immunity against microbial infections. The contribution of the two receptor types to plant immunity differs spatially ...and temporally. The ongoing identification of new plant cell surface immune receptors and their microbial-derived immunogenic ligands reveal a previously unexpected complexity of plant surface sensors involved in the detection of specific microbial species. Comparative analyses of the plant species distribution of cell surface immune receptors indicate that plants harbor larger sets of genus- or species-specific surface receptors in addition to very few widespread pattern sensors. Leucine-rich repeat surface and intracellular immune sensors emerge as two polymorphic receptor classes whose evolutionary trajectories appear to be linked. This is consistent with their functional cooperativity in providing full plant immunity.
Rice feeds more than half of the world's population. Rice blast, caused by the fungal pathogen Magnaporthe oryzae, and bacterial blight, caused by the bacterial pathogen Xanthomonas oryzae pv. ...oryzae, are major constraints to rice production worldwide. Genome sequencing and extensive molecular analysis has led to the identification of many new pathogen-associated molecular patterns (PAMPs) and avirulence and virulence effectors in both pathogens, as well as effector targets and receptors in the rice host. Characterization of these effectors, host targets, and resistance genes has provided new insight into innate immunity in plants. Some of the new findings, such as the binding activity of X. oryzae transcriptional activator-like (TAL) effectors to specific rice genomic sequences, are being used for the development of effective disease control methods and genome modification tools. This review summarizes the recent progress toward understanding the recognition and signaling events that govern rice innate immunity.
Pattern recognition receptors (PRRs) and nucleotide-binding domain and leucine-rich repeat (LRR)-containing proteins (NLRs) initiate pattern-triggered immunity (PTI) and effector-triggered immunity ...(ETI), respectively, each associated with the activation of an overlapping set of defence genes. The regulatory mechanism behind this convergence of PTI- and ETI-mediated defence gene induction remains elusive.
We generated transgenic Arabidopsis plants that enable conditional NLR activation without pathogen infection to dissect NLR- and PRR-mediated transcriptional signals. A comparative analysis of over 40 transcriptome datasets linked calmodulin-binding transcription activators (CAMTAs) to the activation of overlapping defence genes in PTI and ETI. We used a dominant camta3 mutant (camta3-D) to assess CAMTA functions in the corresponding transcriptional regulation.
Transcriptional regulation by NLRs, although highly similar to PTI responses, can be established independently of pathogen-associated molecular pattern (PAMP) perception, defence phytohormones and host cell death. Conditional expression of the N-terminal coiled-coil domain of the barley MLA (Mildew resistance locus A) NLR is sufficient to trigger similar transcriptional reprogramming as full-length NLRs. CAMTA-binding motifs are overrepresented in the 5′ regulatory regions of the identified primary immune response genes, consistent with their altered expression and disease resistance responses in camta3-D plants.
We propose that CAMTA-mediated transcriptional regulation defines an early convergence point in NLR- and PRR-mediated signalling.
Chloroplasts are key players in plant immune signaling, contributing to not only de novo synthesis of defensive phytohormones but also the generation of reactive oxygen and nitrogen species following ...activation of pattern recognition receptors or resistance (R) proteins. The local hypersensitive response (HR) elicited by R proteins is underpinned by chloroplast-generated reactive oxygen species. HR-induced lipid peroxidation generates important chloroplast-derived signaling lipids essential to the establishment of systemic immunity. As a consequence of this pivotal role in immunity, pathogens deploy effector complements that directly or indirectly target chloroplasts to attenuate chloroplast immunity (CI). Our review summarizes the current knowledge of CI signaling and highlights common pathogen chloroplast targets and virulence strategies. We address emerging insights into chloroplast retrograde signaling in immune responses and gaps in our knowledge, including the importance of understanding chloroplast heterogeneity and chloroplast involvement in intraorganellular interactions in host immunity.
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