Nucleo-cytoplasmic distribution of SAP18 reveals its dual function in splicing regulation and heat-stress response in Arabidopsis.

Dynamic shuttling of proteins between the nucleus and cytoplasm orchestrates vital functions in eukaryotes. Here, we reveal the multifaceted functions of Arabidopsis Sin3-associated protein 18 kDa (SAP18) in the regulation of development and heat-stress tolerance. Proteomic analysis demonstrated that SAP18 is a core component of the nuclear apoptosis- and splicing-associated protein (ASAP) complex in Arabidopsis, contributing to the precise splicing of genes associated with leaf development.

Activation of plant immunity through conversion of a helper NLR homodimer into a resistosome.

Nucleotide-binding domain and leucine-rich repeat (NLR) proteins can engage in complex interactions to detect pathogens and execute a robust immune response via downstream helper NLRs. However, the biochemical mechanisms of helper NLR activation by upstream sensor NLRs remain poorly understood. Here, we show that the coiled-coil helper NLR NRC2 from Nicotiana benthamiana accumulates in vivo as a homodimer that converts into a higher-order oligomer upon activation by its upstream virus disease resistance protein Rx.

Bioengineering a plant NLR immune receptor with a robust binding interface toward a conserved fungal pathogen effector.

Bioengineering of plant immune receptors has emerged as a key strategy for generating novel disease resistance traits to counteract the expanding threat of plant pathogens to global food security. However, current approaches are limited by rapid evolution of plant pathogens in the field and may lack durability when deployed. Here, we show that the rice nucleotide-binding, leucine-rich repeat (NLR) immune receptor Pik-1 can be engineered to respond to a conserved family of effectors from the multihost blast fungus pathogen .

Zinc-finger (ZiF) fold secreted effectors form a functionally diverse family across lineages of the blast fungus Magnaporthe oryzae.

Filamentous plant pathogens deliver effector proteins into host cells to suppress host defence responses and manipulate metabolic processes to support colonization. Understanding the evolution and molecular function of these effectors provides knowledge about pathogenesis and can suggest novel strategies to reduce damage caused by pathogens. However, effector proteins are highly variable, share weak sequence similarity and, although they can be grouped according to their structure, only a few structurally conserved effector families have been functionally characterized to date.

The exocyst complex is an evolutionary battleground in plant-microbe interactions.

Exocytosis is a conserved trafficking pathway that transports secretory vesicles to the extracellular space, replenishes the plasma membrane and is essential for establishing cell polarity. Its spatiotemporal regulation is mediated by an evolutionary conserved octameric tethering complex, the exocyst. In plants, certain subunits of this complex have diversified and acquired multiple functions, including a central role in defense against pathogens and pests.

Allelic compatibility in plant immune receptors facilitates engineering of new effector recognition specificities.

Engineering the plant immune system offers genetic solutions to mitigate crop diseases caused by diverse agriculturally significant pathogens and pests. Modification of intracellular plant immune receptors of the nucleotide-binding leucine-rich repeat (NLR) receptor superfamily for expanded recognition of pathogen virulence proteins (effectors) is a promising approach for engineering disease resistance. However, engineering can cause NLR autoactivation, resulting in constitutive defense responses that are deleterious to the plant.

Effector target-guided engineering of an integrated domain expands the disease resistance profile of a rice NLR immune receptor.

A subset of plant intracellular NLR immune receptors detect effector proteins, secreted by phytopathogens to promote infection, through unconventional integrated domains which resemble the effector's host targets. Direct binding of effectors to these integrated domains activates plant defenses. The rice NLR receptor Pik-1 binds the effector AVR-Pik through an integrated heavy metal-associated (HMA) domain.

Pathways to engineering plant intracellular NLR immune receptors.

Factors including climate change and increased global exchange are set to escalate the prevalence of plant diseases, posing an unprecedented threat to global food security and making it more challenging to meet the demands of an ever-growing population. As such, new methods of pathogen control are essential to help with the growing danger of crop losses to plant diseases. The intracellular immune system of plants utilizes nucleotide-binding leucine-rich repeat (NLR) receptors to recognize and activate defense responses to pathogen virulence proteins (effectors) delivered to the host.

Plant autophagosomes mature into amphisomes prior to their delivery to the central vacuole.

Autophagosomes are double-membraned vesicles that traffic harmful or unwanted cellular macromolecules to the vacuole for recycling. Although autophagosome biogenesis has been extensively studied, autophagosome maturation, i.e.

A blast fungus zinc-finger fold effector binds to a hydrophobic pocket in host Exo70 proteins to modulate immune recognition in rice.

Exocytosis plays an important role in plant-microbe interactions, in both pathogenesis and symbiosis. Exo70 proteins are integral components of the exocyst, an octameric complex that mediates tethering of vesicles to membranes in eukaryotes. Although plant Exo70s are known to be targeted by pathogen effectors, the underpinning molecular mechanisms and the impact of this interaction on infection are poorly understood.

Functional diversification gave rise to allelic specialization in a rice NLR immune receptor pair.

Cooperation between receptors from the nucleotide-binding, leucine-rich repeats (NLR) superfamily is important for intracellular activation of immune responses. NLRs can function in pairs that, upon pathogen recognition, trigger hypersensitive cell death and stop pathogen invasion. Natural selection drives specialization of host immune receptors towards an optimal response, whilst keeping a tight regulation of immunity in the absence of pathogens.

Assessment of Pathogen Effector Binding to Host Proteins by Surface Plasmon Resonance.

The mechanisms of virulence and immunity are often governed by molecular interactions between pathogens and host proteins. The study of these interactions has major implications on understanding virulence activities, and how the host immune system recognizes the presence of pathogens to initiate an immune response. Frequently, the association between pathogen molecules and host proteins are assessed using qualitative techniques.

The allelic rice immune receptor Pikh confers extended resistance to strains of the blast fungus through a single polymorphism in the effector binding interface.

Arms race co-evolution drives rapid adaptive changes in pathogens and in the immune systems of their hosts. Plant intracellular NLR immune receptors detect effectors delivered by pathogens to promote susceptibility, activating an immune response that halts colonization. As a consequence, pathogen effectors evolve to escape immune recognition and are highly variable.

A molecular roadmap to the plant immune system.

Plant diseases caused by pathogens and pests are a constant threat to global food security. Direct crop losses and the measures used to control disease ( application of pesticides) have significant agricultural, economic, and societal impacts. Therefore, it is essential that we understand the molecular mechanisms of the plant immune system, a system that allows plants to resist attack from a wide variety of organisms ranging from viruses to insects.

Protein engineering expands the effector recognition profile of a rice NLR immune receptor.

Plant nucleotide binding, leucine-rich repeat (NLR) receptors detect pathogen effectors and initiate an immune response. Since their discovery, NLRs have been the focus of protein engineering to improve disease resistance. However, this approach has proven challenging, in part due to their narrow response specificity.

N-terminal β-strand underpins biochemical specialization of an ATG8 isoform.

Autophagy-related protein 8 (ATG8) is a highly conserved ubiquitin-like protein that modulates autophagy pathways by binding autophagic membranes and a number of proteins, including cargo receptors and core autophagy components. Throughout plant evolution, ATG8 has expanded from a single protein in algae to multiple isoforms in higher plants. However, the degree to which ATG8 isoforms have functionally specialized to bind distinct proteins remains unclear.

Uncoiling CNLs: Structure/Function Approaches to Understanding CC Domain Function in Plant NLRs.

Plant nucleotide-binding leucine-rich repeat receptors (NLRs) are intracellular pathogen receptors whose N-terminal domains are integral to signal transduction after perception of a pathogen-derived effector protein. The two major plant NLR classes are defined by the presence of either a Toll/interleukin-1 receptor (TIR) or a coiled-coil (CC) domain at their N-terminus (TNLs and CNLs). Our knowledge of how CC domains function in plant CNLs lags behind that of how TIR domains function in plant TNLs.

Publisher Correction: Polymorphic residues in rice NLRs expand binding and response to effectors of the blast pathogen.

In the version of this Article originally published, in Fig. 1b the single-letter code for the amino acid polymorphism at position 46 in the schematic of the AVR-PikE variant was incorrectly given as 'H'. The correct amino acid is 'N'.

Polymorphic residues in rice NLRs expand binding and response to effectors of the blast pathogen.

Accelerated adaptive evolution is a hallmark of plant-pathogen interactions. Plant intracellular immune receptors (NLRs) often occur as allelic series with differential pathogen specificities. The determinants of this specificity remain largely unknown.

Lessons in Effector and NLR Biology of Plant-Microbe Systems.

A diversity of plant-associated organisms secrete effectors-proteins and metabolites that modulate plant physiology to favor host infection and colonization. However, effectors can also activate plant immune receptors, notably nucleotide-binding domain and leucine-rich repeat region (NLR)-containing proteins, enabling plants to fight off invading organisms. This interplay between effectors, their host targets, and the matching immune receptors is shaped by intricate molecular mechanisms and exceptionally dynamic coevolution.

Taking the stage: effectors in the spotlight.

Plant pathogens are a serious threat to agriculture and to global food security, causing diverse crop diseases which lead to extensive annual yield losses. Production of effector proteins by pathogens, to manipulate host cellular processes, is central to their success. An understanding of fundamental effector biology is key to addressing the threat posed by these pathogens.

Emerging oomycete threats to plants and animals.

Oomycetes, or water moulds, are fungal-like organisms phylogenetically related to algae. They cause devastating diseases in both plants and animals. Here, we describe seven oomycete species that are emerging or re-emerging threats to agriculture, horticulture, aquaculture and natural ecosystems.

ATG8 Expansion: A Driver of Selective Autophagy Diversification?

Selective autophagy is a conserved homeostatic pathway that involves engulfment of specific cargo molecules into specialized organelles called autophagosomes. The ubiquitin-like protein ATG8 is a central player of the autophagy network that decorates autophagosomes and binds to numerous cargo receptors. Although highly conserved across eukaryotes, ATG8 diversified from a single protein in algae to multiple isoforms in higher plants.