62 research outputs found
Exploration of phyllosphere microbiomes in wheat varieties with differing aphid resistance
No full textBackground:
Leaf-associated microbes play an important role in plant development and response to exogenous stress. Insect herbivores are known to alter the phyllosphere microbiome. However, whether the host plant’s defense against insects is related to the phyllosphere microbiome remains mostly elusive. Here, we investigated bacterial communities in the phyllosphere and endosphere of eight wheat cultivars with differing aphid resistance, grown in the same farmland.
Results:
The bacterial community in both the phyllosphere and endosphere showed significant differences among most wheat cultivars. The phyllosphere was connected to more complex and stable microbial networks than the endosphere in most wheat cultivars. Moreover, the genera Pantoea, Massilia, and Pseudomonas were found to play a major role in shaping the microbial community in the wheat phyllosphere. Additionally, wheat plants showed phenotype-specific associations with the genera Massilia and Pseudomonas. The abundance of the genus Exiguobacterium in the phyllosphere exhibited a significant negative correlation with the aphid hazard grade in the wheat plants.
Conclusion:
Communities of leaf-associated microbes in wheat plants were mainly driven by the host genotype. Members of the genus Exiguobacterium may have adverse effects on wheat aphids. Our findings provide new clues supporting the development of aphid control strategies based on phyllosphere microbiome engineering
Parasitic plants--A CuRe for what ails thee
No full textParasitic plants cause dramatic changes in ecosystems and represent a serious risk to agriculture by attacking crops of high economic importance. A highly conserved part of plant immune systems is the recognition of microbe-associated molecular patterns (MAMPs) by plasma membrane-localized pattern recognition receptors (PRRs) that initiate an effective immune response upon activation (1). Whether parasitic plants are also sensed as foes by these receptors was until now unknown. On page 478 of this issue, Hegenauer et al. report the identification of a canonical PRR that is required for responsiveness to a MAMP-like molecule from the parasitic plant Cuscuta reflexa and protects plants against parasitic attack (2). This finding opens the possibility of biotechnological applications for sustainable crop protection against these devastating parasites
The LysM receptor kinase CERK1 mediates bacterial perception in Arabidopsis
No full textPlants use pattern recognition receptors (PRRs) to perceive pathogen-associated molecular pattern (PAMPs) and initiate defence responses. PAMP-triggered immunity (PTI) plays an important role in general resistance, and constrains the growth of most microbes on plants. Despite the importance of PRRs in plant immunity, the vast majority of them remain to be identified. We recently showed that the Arabidopsis LysM receptor kinase CERK1 is required not only for chitin signalling and fungal resistance, but plays an essential role in restricting bacterial growth on plants. We proposed that CERK1 may mediate the perception of a bacterial PAMP, or an endogenous plant cell wall component released during infection, through its extracellular carbohydrate-binding LysM-motifs. Here we report reduced activation of a PAMP-induced defence response on plants lacking the CERK1 gene after treatment with crude bacterial extracts. This demonstrates that CERK1 mediates perception of an unknown bacterial PAMP in Arabidopsis
Improving crop disease resistance : lessons from research on Arabidopsis and tomato
No full textOne of the great challenges for food security in the 21st century is to improve yield stability through the development of disease-resistant crops. Crop research is often hindered by the lack of molecular tools, growth logistics, generation time and detailed genetic annotations, hence the power of model plant species. Our knowledge of plant immunity today has been largely shaped by the use of models, specifically through the use of mutants. We examine the importance of Arabidopsis and tomato as models in the study of plant immunity and how they help us in revealing a detailed and deep understanding of the various layers contributing to the immune system. Here we describe examples of how knowledge from models can be transferred to economically important crops resulting in new tools to enable and accelerate classical plant breeding. We will also discuss how models, and specifically transcriptomics and effectoromics approaches, have contributed to the identification of core components of the defense response which will be key to future engineering of durable and sustainable disease resistance in plants
The Arabidopsis protein phosphatase PP2C38 negatively regulates the central immune kinase BIK1
No full textPlants recognize pathogen-associated molecular patterns (PAMPs) via cell surface-localized pattern recognition receptors (PRRs), leading to PRR-triggered immunity (PTI). The Arabidopsis cytoplasmic kinase BIK1 is a downstream substrate of several PRR complexes. How plant PTI is negatively regulated is not fully understood. Here, we identify the protein phosphatase PP2C38 as a negative regulator of BIK1 activity and BIK1-mediated immunity. PP2C38 dynamically associates with BIK1, as well as with the PRRs FLS2 and EFR, but not with the co-receptor BAK1. PP2C38 regulates PAMP-induced BIK1 phosphorylation and impairs the phosphorylation of the NADPH oxidase RBOHD by BIK1, leading to reduced oxidative burst and stomatal immunity. Upon PAMP perception, PP2C38 is phosphorylated on serine 77 and dissociates from the FLS2/EFR-BIK1 complexes, enabling full BIK1 activation. Together with our recent work on the control of BIK1 turnover, this study reveals another important regulatory mechanism of this central immune component
The tomato Prf complex is a molecular trap for bacterial effectors based on Pto transphosphorylation
No full textThe bacteria Pseudomonas syringae is a pathogen of many crop species and one of the model pathogens for studying plant and bacterial arms race coevolution. In the current model, plants perceive bacteria pathogens via plasma membrane receptors, and recognition leads to the activation of general defenses. In turn, bacteria inject proteins called effectors into the plant cell to prevent the activation of immune responses. AvrPto and AvrPtoB are two such proteins that inhibit multiple plant kinases. The tomato plant has reacted to these effectors by the evolution of a cytoplasmic resistance complex. This complex is compromised of two proteins, Prf and Pto kinase, and is capable of recognizing the effector proteins. How the Pto kinase is able to avoid inhibition by the effector proteins is currently unknown. Our data shows how the tomato plant utilizes dimerization of resistance proteins to gain advantage over the faster evolving bacterial pathogen. Here we illustrate that oligomerisation of Prf brings into proximity two Pto kinases allowing them to avoid inhibition by the effectors by transphosphorylation and to activate immune responses
Regulation of sucrose phosphate synthase in vascular bundles of Washington navel orange fruit (Citrus Sinensis L. Osbeck) by a protein kinase and a protein phosphatase
No full textEditorial : mechanisms regulating immunity in plants
No full textPlants are constantly exposed to potential pathogens in their environment. The intimate associations involved in plant-microbe interactions have influenced the evolution of a multi-faceted surveillance system to detect and respond to both the presence of microbes at the cell surface as well as the presence of pathogenic effectors inside the cell. Here, we bring together 11 reviews that discuss current concepts in plant innate immunity with a focus on protein biology and proteomics (Figure 1)
Sink activity in Washington navel orange fruit borne on leafy and leafless inflorescences
No full textCautionary Notes on the Use of C-Terminal BAK1 Fusion Proteins for Functional Studies
No full textDetailed phenotypic characterization reveals that several BAK1 fusion proteins with C-terminal tags strongly impair complementation of bak1 null mutants with respect to responsiveness to the bacterial pathogen-associated molecular patterns flagellin and EF-Tu. This raises concerns about the widespread use of such protein variants of this important regulatory Leu-rich repeat receptor-like kinase (RLK) for functional analyses of RLK-based signaling
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