eLife: latest articles by subject

Cardenolide toxin diversity impacts monarch butterfly growth and sequestration

aa337@cornell.edu (Amy P Hastings) — Mon, 16 Mar 2026 00:00:00 +0000

In coevolutionary interactions, host plants accrue novel chemical defenses that specialist herbivores counter by detoxification and sometimes sequestration. We recently found unusual nitrogen- and sulfur-containing (N,S-) cardenolides in some milkweeds—highly toxic compounds that monarch butterflies (Danaus plexippus) detoxify during sequestration. We hypothesized that the N,S-cardenolides in Asclepias curassavica (uscharin and voruscharin) would reduce caterpillar performance and sequestration more than other abundant related cardenolides (15-hydroxy-calotropin, frugoside, calactin). Cardenolides generally increased feeding relative to controls, but voruscharin was not stimulatory and substantially reduced growth efficiency. Exposure to either N,S-cardenolide produced the lowest sequestration and reduced sequestration efficiency, consistent with detoxification limiting toxin retention. We next tested whether toxin mixtures impose additional costs relative to individual compounds. We prepared two mixtures, one with equal concentrations of five cardenolides and a ‘realistic mixture’ reflecting natural proportions. Relative to the average of single compounds, mixtures reduced feeding, growth, sequestration, and sequestration efficiency, indicating phytochemical diversity effects exceeded expectations from an additive model. The two mixtures similarly reduced growth, but feeding on the realistic mixture yielded the lowest sequestration. We conclude that coevolution can produce highly specialized defense metabolites such as N,S-cardenolides that thwart even sequestering herbivores, and that phytochemical mixtures strengthen plant defense.

Rice stripe virus utilizes a Laodelphax striatellus salivary carbonic anhydrase to facilitate plant infection by direct molecular interaction

huoy@im.ac.cn (Jie Yang) — Tue, 06 Jan 2026 00:00:00 +0000

Plant viruses typically rely on insect vectors for transmission between plants, with insect salivary proteins playing critical roles in this process. In this study, we demonstrate how Laodelphax striatellus salivary carbonic anhydrase (LssaCA) promotes rice stripe virus (RSV) infection in plants. We discovered that LssaCA directly binds to RSV nucleocapsid protein (NP) in insect salivary glands. This LssaCA-NP complex interacts with a rice thaumatin-like protein (OsTLP) that possesses endo-β-1,3-glucanase activity potentially degrading callose. Upon binding, the LssaCA-NP complex significantly enhances OsTLP enzymatic activity. We further clarify that both L. striatellus feeding and RSV infection induce callose deposition. The tripartite LssaCA-NP-OsTLP interaction enhances callose degradation, thereby facilitating RSV infection via its insect vector. This study provides new insights into complex virus-insect-plant tripartite interactions mediated by insect salivary proteins, with broad implications for numerous plant viruses transmitted by insect vectors.

An increase of NPY1 expression leads to inhibitory phosphorylation of PIN-FORMED (PIN) proteins and suppression of pinoid (pid) null mutants

sbriggs@ucsd.edu (Michael Mudgett) — Wed, 17 Dec 2025 00:00:00 +0000

The PINOID (PID) protein kinase is required for flower initiation in Arabidopsis. The pid mutants fail to initiate flowers on inflorescences, a phenotype that is mimicked by disrupting either the NAKED PINS IN YUC MUTANTS (NPY) gene family or PIN FORMED 1 (PIN1). Both PID and NPY1 have been reported to positively modulate PIN-mediated polar auxin transport. Here, we show that overexpression of NPY1 (NPY1 OE) completely suppressed pid null mutants, demonstrating that NPY1 functions downstream of PID. NPY1 OE triggered phosphorylation of PIN proteins at multiple sites that are mostly different from the previously characterized phosphorylation sites regardless of the presence of PID. Phosphorylation of the newly identified PIN sites in NPY1 OE plants likely leads to the inhibition of PIN functions, as we previously showed that pid is suppressed by decreasing PIN1 gene dosage or decreasing PIN1 activity. Furthermore, we show that the Ser/Thr-rich C-terminal motif in NPY1 is phosphorylated and is required for pid suppression by NPY1 OE. Overexpression of NPY1 that lacked the C-terminal motif (NPY1∆C) failed to rescue pid, but overexpression of NPY1∆C was still able to trigger phosphorylation of PIN proteins, including PIN2, which is known to cause agravitropic roots when mutated. NPY1∆C overexpression plants displayed a complete loss of root gravitropic response, likely caused by PIN2 phosphorylation. Our results suggest a pathway for auxin-mediated flower initiation, in which PID regulates NPY1 accumulation and/or activity, and subsequently, NPY1 triggers phosphorylation of PIN proteins and inhibition of PIN functions.

Life-cycle-related gene expression patterns in the brown algae

cock@sb-roscoff.fr (Benjamin Noel) — Wed, 19 Nov 2025 00:00:00 +0000

Brown algae are important primary constituents of marine coastal ecosystems, characterised by complex life cycles and various levels of complex multicellular development. However, the molecular processes that underlie development and life cycle progression in the brown algae remain poorly understood. In this study, pairwise comparisons of gametophyte and sporophyte transcriptomes across 10 diverse brown algal species showed that the total number of genes exhibiting generation-biased or generation-specific expression in each species was correlated with the degree of dimorphism between life cycle generations. However, analysis of gene ontology terms assigned to the generation-biased/generation-specific genes indicated that each generation (i.e. the sporophyte and the gametophyte) also has characteristic broad life-cycle-related features that have been conserved during evolution. A more detailed analysis of Ectocarpus species 7 identified progressive transcriptome changes over its entire life cycle, with a particularly marked change in transcriptome composition during the first day of sporophyte development, characterised by downregulation of flagellar and transcription factor genes and upregulation of a subset of translation genes. Comparison with a similar transcriptomic time series for the evolutionarily distant (about 250 My) brown alga Dictyota dichotoma indicated considerable conservation of co-expressed gene modules between the two species, particularly for modules that were enriched in genes assigned to evolutionarily conserved functional categories. This study therefore identified broad life-cycle- and development-related patterns of gene expression that are conserved across the brown algae.

Fifteenth century CE Bolivian maize reveals genetic affinities with ancient Peruvian maize

lovis@msu.edu (Addie Thompson) — Tue, 18 Nov 2025 00:00:00 +0000

Previous archaeological and anthropological studies have demonstrated the myriad of ways that cultural and political systems shape access to food and food preferences. However, few studies have conducted a biocultural analysis linking specific genotypic/phenotypic traits as evidence of cultural selection in ancient contexts. Here, we provide insight into this topic through ancient genome data from Bolivian maize dating to ~500–600 BP, included as an offering with the mummified remains of a young girl. These data are compared to 16 previously published archaeological maize samples spanning at least 5000 years of evolution, and 226 modern maize samples. Our phylogenetic analysis showed that the archaeological Bolivian maize (aBM) has the closest genetic distance to the archaeological maize from ancient Peru, which in turn shared the most similarities with archaeological Peruvian maize. During the period of interaction between the Inca state and local polities in the central Andes and consequent interactions with local agricultural traditions, the genetic diversity of maize increased. Ovule development in modern maize was selected and compared to those in archaeological specimens, revealing evidence of targeted breeding strategies aimed at improving seed quality and yield. While the cultural origin of the maize – either Inca or local Aymara – is uncertain, we demonstrate that the samples are most similar to Peruvian maize and potential targeted selection strategies for enhanced growth were well established by the 15^th century.

Short heat shock factor A2 regulates heat resistance and growth balance in Arabidopsis

qixiaoting@cnu.edu.cn (Jiaqi Zhao) — Mon, 03 Nov 2025 00:00:00 +0000

Cells prevent heat damage through the highly conserved canonical heat stress response (HSR), where heat shock factors (HSFs) bind heat shock elements (HSEs) to activate heat shock proteins (HSPs). Plants generate short HSFs (S-HSFs) derived from HSF splicing variants, yet their functions remain poorly understood. While an enhanced canonical HSR confers thermotolerance, its hyperactivation inhibits plant growth. How plants prevent this hyperactivation to ensure proper growth remains unknown. Here, we report that Arabidopsis S-HsfA2, S-HsfA4c, and S-HsfB1 confer sensitivity to extreme heat (45°C) and constitute new HSF types featuring a unique truncated DNA-binding domain (tDBD). This tDBD binds a new heat-regulated element (HRE), which confers minimal promoter heat-responsiveness and exhibits heat stress sensing and transmission patterns. Using S-HsfA2, we investigated whether and how S-HSFs prevent canonical HSR hyperactivation. HSP17.6B, a common direct target of HsfA2 and S-HsfA2, confers thermotolerance; however, its overexpression partially causes HSR hyperactivation. Moreover, HRE–HRE-like and HSE elements mediate the HSP17.6B promoter’s heat response. We further show S-HsfA2 alleviates hyperactivation via two mechanisms: (1) S-HsfA2 negatively regulates HSP17.6B via the HRE–HRE-like element, establishing a noncanonical HSR (S-HsfA2-HRE-HSP17.6B) that antagonistically represses HsfA2-activated HSP17.6B expression. (2) S-HsfA2 binds the HsfA2 DBD, preventing HsfA2 from binding HSEs and thereby attenuating HsfA2-activated HSP17.6B promoter activity. Overall, our findings highlight the essential role of S-HsfA2 in preventing hyperactivation of plant heat tolerance to maintain proper growth.

Companion cells with high florigen production express other small proteins and reveal a nitrogen-sensitive FT repressor

takato@uw.edu (Akane Kubota) — Thu, 30 Oct 2025 00:00:00 +0000

The precise onset of flowering is crucial for successful reproduction. In longer days, the florigen gene FLOWERING LOCUS T (FT) is induced in specific leaf phloem companion cells in Arabidopsis. However, the molecular nature of these cells remains elusive. Here, we utilized bulk nuclei RNA-seq and single nuclei RNA (snRNA)-seq to investigate transcription in FT-expressing cells and other companion cells. Our bulk nuclei RNA-seq demonstrated that FT-expressing cells in cotyledons and true leaves showed differences in FT repressor gene expression. Within true leaves, our snRNA-seq analysis revealed that companion cells with high FT expression form a unique cluster. The cluster expresses other genes encoding small proteins, including the flowering and stem growth inducer FPF1-LIKE PROTEIN 1 (FLP1) and the anti-florigen BROTHER OF FT AND TFL1 (BFT). We also found that the promoters of FT and the genes co-expressed with FT in the cluster were enriched for the binding motif of NITRATE-INDUCIBLE GARP-TYPE TRANSCRIPTIONAL REPRESSOR 1 (NIGT1). Overexpression of NIGT1.2 and NIGT1.4 repressed FT and delayed flowering under nitrogen-rich conditions, implying the roles of NIGT1s as nitrogen-dependent FT repressors. Taken together, our results indicate that unique FT-expressing phloem cells may produce multiple systemic signals to regulate plant growth and development.

Structure-guided secretome analysis of gall-forming microbes offers insights into effector diversity and evolution

soham.mukhopadhyay.1@ulaval.ca (Edel Perez-Lopez) — Tue, 07 Oct 2025 00:00:00 +0000

Phytopathogens secrete effector molecules to manipulate host immunity and metabolism. Recent advances in structural genomics have identified fungal effector families whose members adopt similar folds despite sequence divergence, highlighting their importance in virulence and immune evasion. To extend the scope of comparative structure-guided analysis to more evolutionarily distant phytopathogens with similar lifestyles, we used AlphaFold2 to predict the 3D structures of the secretome from selected plasmodiophorid, oomycete, and fungal gall-forming pathogens. Clustering protein folds based on structural homology revealed species-specific expansions and a low abundance of known orphan effector families. We identified novel sequence-unrelated but structurally similar (SUSS) effector clusters, rich in conserved motifs such as 'CCG' and 'RAYH'. We demonstrate that these motifs likely play a central role in maintaining the overall fold. We also identified a SUSS cluster adopting a nucleoside hydrolase-like fold conserved among various gall-forming microbes. Notably, ankyrin proteins (ANK) were significantly expanded in gall-forming plasmodiophorids, with most being highly expressed during clubroot disease, suggesting a role in pathogenicity. Subsequently, we screened ANK proteins against Arabidopsis immunity hubs using AlphaFold-Multimer and verified one of the positive results by Y2H and BiFC assays to show that the ankyrin effector PbANK1 targets host MPK3 and a zinc-binding dehydrogenase. These findings suggest a potential new mechanism in which ANK effectors target multiple host proteins involved in stress sensing, opening a novel avenue to study the role of ANK in host–pathogen interactions. Altogether, this study advances our understanding of secretome landscapes in gall-forming microbes and provides a valuable resource for broadening structural phylogenomic studies across diverse phytopathogens.

Strip cropping shows promising increases in ground beetle community diversity compared to monocultures

luuk.croijmans@wur.nl (Dirk F van Apeldoorn) — Tue, 23 Sep 2025 00:00:00 +0000

Global biodiversity is declining at an unprecedented rate, with agriculture as one of the major drivers. There is mounting evidence that intercropping can increase insect biodiversity while maintaining or increasing yield. Yet, intercropping is often considered impractical for mechanized farming systems. Strip cropping is a type of intercropping that is compatible with standard farm machinery and has been pioneered by Dutch farmers since 2014. Here, we present ground beetle data from four organically managed experimental farms across four years. Ground beetles are sensitive to changes in habitats and disturbances, and hold keystone positions in agroecosystem food webs. We show that strip cropping systems can enhance ground beetle biodiversity, while other studies showed that these increases have been achieved without incurring major yield loss. Strip-cropped fields had on average 15% more ground beetle species and 30% more individuals than monocultural fields. The higher ground beetle richness in strip crops was explained by the merger of crop-related ground beetle communities, rather than by ground beetle species unique to strip cropping systems. The increase in field-level beetle species richness in organic agriculture through strip cropping approached increases found for other readily deployed biodiversity conservation methods, like shifting from conventional to organic agriculture (+19% –+23%). This indicates that strip cropping is a potentially useful tool supporting ground beetle biodiversity in agricultural fields without compromising food production.

Molecular architecture of thylakoid membranes within intact spinach chloroplasts

wojciech.wietrzynski@unibas.ch (Benjamin D Engel) — Thu, 11 Sep 2025 00:00:00 +0000

Thylakoid membranes coordinate the light reactions of photosynthesis across multiple scales, coupling the architecture of an elaborate membrane network to the spatial organization of individual protein complexes embedded within this network. Previously, we used in situ cryo-electron tomography (cryo-ET) to reveal the native thylakoid architecture of the green alga Chlamydomonas reinhardtii (Engel et al., 2015) and then map the molecular organization of these thylakoids with single-molecule precision (Wietrzynski et al., 2020). However, it remains to be shown how generalizable this green algal blueprint is to the thylakoids of vascular plants, which possess distinct membrane architecture subdivided into grana stacks interconnected by non-stacked stromal lamellae. Here, we continue our cryo-ET investigation to reveal the molecular architecture of thylakoids within intact chloroplasts isolated from spinach (Spinacia oleracea). We visualize the fine ultrastructural details of grana membranes, as well as interactions between thylakoids and plastoglobules. We apply AI-based computational approaches (Lamm et al., 2024) to quantify the organization of photosynthetic complexes within the plane of the thylakoid membrane and across adjacent stacked membranes. Our analysis reveals that the molecular organization of thylakoid membranes in vascular plants and green algae is strikingly similar. We find that PSII organization is non-crystalline and has uniform concentration both within the membrane plane and across stacked grana membranes. Similar to C. reinhardtii, we observe strict lateral heterogeneity of PSII and PSI at the boundary between appressed and non-appressed thylakoid domains, with no evidence for a distinct grana margin region where these complexes have been proposed to intermix. Based on these measurements, we support a simple two-domain model for the molecular organization of thylakoid membranes in both green algae and plants.

Making conferences in the plant sciences more inclusive through community recommendations

pbaldrich@ucdavis.edu (Adriana Hernandez) — Wed, 20 Aug 2025 00:00:00 +0000

An unwelcoming climate and culture at scientific conferences is an obstacle to retaining scientists with marginalized identities. Here we describe how a number of professional societies in the plant sciences, mostly based in the United States, collaborated on a project called ROOT & SHOOT (short for Rooting Out Oppression Together and SHaring Our Outcomes Transparently) to make conferences in the field more inclusive. The guidelines we developed, and our efforts to implement them in 2023 and 2024, are summarized here to assist other conference organizers with creating more inclusive conferences.

How plants pick their friends

m.udvardi@uq.edu.au (Estelle Grundy) — Thu, 17 Jul 2025 00:00:00 +0000

A protein called RIN4 has a central role in helping legumes such as soybean and the bacteria rhizobia to develop a mutually beneficial relationship.

Competence for transcellular infection in the root cortex involves a post-replicative, cell-cycle exit decision in Medicago truncatula

morgane.batzenschlager@biologie.uni-freiburg.de (Anna Boiger) — Fri, 04 Jul 2025 00:00:00 +0000

During root nodule symbiosis (RNS), cell-division activity is reinitiated and sustained in the root cortex to create a hospitable cellular niche. Such a temporary and spatially confined site is required to render host cells compatible with the intracellular progression of rhizobia. Although it has been suggested that early infection events might involve a pre-mitotic cell-cycle arrest, this process has not been dissected with cellular resolution. Here, we show that a dual-color Medicago histone reporter robustly identifies cells with different mitotic or endoreduplication activities in the root cortex. By imaging deep root tissues, we found that a confined trajectory of cortical cells that are transcellularly passed by infection threads is in a stage of the cell cycle that is distinct from directly adjacent cells. Distinctive features of infected cells include nuclear widening and large-scale chromatin rearrangements consistent with a cell-cycle exit prior to differentiation. Using a combination of fluorescent reporters demarcating cell-cycle phase progression, we confirmed that a reduced proliferation potential and modulating the G2/M transition, a process possibly controlled by the NF-YA1 transcription factor, mark the success of rhizobial delivery to nodule cells.

Interdependence of plasma membrane nanoscale dynamics of a kinase and its cognate substrate underlies Arabidopsis response to viral infection

veronique.germain@u-bordeaux.fr (Anne Flore Deroubaix) — Fri, 02 May 2025 00:00:00 +0000

Plant viruses represent a risk to agricultural production and as only a few treatments exist, it is urgent to identify resistance mechanisms and factors. In plant immunity, plasma membrane (PM)-localized proteins play an essential role in sensing the extracellular threat presented by bacteria, fungi, or herbivores. Viruses are intracellular pathogens and as such the role of the plant PM in detection and resistance against viruses is often overlooked. We investigated the role of the partially PM-bound Calcium-dependent protein kinase 3 (CPK3) in viral infection and we discovered that it displayed a specific ability to hamper viral propagation over CPK isoforms that are involved in immune response to extracellular pathogens. More and more evidence supports that the lateral organization of PM proteins and lipids underlies signal transduction in plants. We showed here that CPK3 diffusion in the PM is reduced upon activation as well as upon viral infection and that such immobilization depended on its substrate, Remorin (REM1.2), a scaffold protein. Furthermore, we discovered that the viral infection induced a CPK3-dependent increase of REM1.2 PM diffusion. Such interdependence was also observable regarding viral propagation. This study unveils a complex relationship between a kinase and its substrate that contrasts with the commonly described co-stabilisation upon activation while it proposes a PM-based mechanism involved in decreased sensitivity to viral infection in plants.

The rhizobial effector NopT targets Nod factor receptors to regulate symbiosis in Lotus japonicus

yrcao@mail.hzau.edu.cn (Christian Staehelin) — Fri, 04 Apr 2025 00:00:00 +0000

It is well documented that type-III effectors are required by Gram-negative pathogens to directly target different host cellular pathways to promote bacterial infection. However, in the context of legume–rhizobium symbiosis, the role of rhizobial effectors in regulating plant symbiotic pathways remains largely unexplored. Here, we show that NopT, a YopT-type cysteine protease of Sinorhizobium fredii NGR234 directly targets the plant’s symbiotic signaling pathway by associating with two Nod factor receptors (NFR1 and NFR5 of Lotus japonicus). NopT inhibits cell death triggered by co-expression of NFR1/NFR5 in Nicotiana benthamiana. Full-length NopT physically interacts with NFR1 and NFR5. NopT proteolytically cleaves NFR5 both in vitro and in vivo, but can be inactivated by NFR1 as a result of phosphorylation. NopT plays an essential role in mediating rhizobial infection in L. japonicus. Autocleaved NopT retains the ability to cleave NFR5 but no longer interacts with NFR1. Interestingly, genomes of certain Sinorhizobium species only harbor nopT genes encoding truncated proteins without the autocleavage site. These results reveal an intricate interplay between rhizobia and legumes, in which a rhizobial effector protease targets NFR5 to suppress symbiotic signaling. NFR1 appears to counteract this process by phosphorylating the effector. This discovery highlights the role of a bacterial effector in regulating a signaling pathway in plants and opens up the perspective of developing kinase-interacting proteases to fine-tune cellular signaling processes in general.

Structure of the Calvin-Benson-Bassham sedoheptulose-1,7-bisphosphatase from the model microalga Chlamydomonas reinhardtii

julien.henri@sorbonne-universite.fr (Julien Henri) — Tue, 01 Apr 2025 00:00:00 +0000

The Calvin-Benson-Bassham cycle (CBBC) performs carbon fixation in photosynthetic organisms. Among the eleven enzymes that participate in the pathway, sedoheptulose-1,7-bisphosphatase (SBPase) is expressed in photo-autotrophs and catalyzes the hydrolysis of sedoheptulose-1,7-bisphosphate (SBP) to sedoheptulose-7-phosphate (S7P). SBPase, along with nine other enzymes in the CBBC, contributes to the regeneration of ribulose-1,5-bisphosphate, the carbon-fixing co-substrate used by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). The metabolic role of SBPase is restricted to the CBBC, and a recent study revealed that the three-dimensional structure of SBPase from the moss Physcomitrium patens was found to be similar to that of fructose-1,6-bisphosphatase (FBPase), an enzyme involved in both CBBC and neoglucogenesis. In this study we report the first structure of an SBPase from a chlorophyte, the model unicellular green microalga Chlamydomonas reinhardtii. By combining experimental and computational structural analyses, we describe the topology, conformations, and quaternary structure of Chlamydomonas reinhardtii SBPase (CrSBPase). We identify active site residues and locate sites of redox- and phospho-post-translational modifications that contribute to enzymatic functions. Finally, we observe that CrSBPase adopts distinct oligomeric states that may dynamically contribute to the control of its activity.

Natural variation in salt-induced changes in root:shoot ratio reveals SR3G as a negative regulator of root suberization and salt resilience in Arabidopsis

mmj55@cornell.edu (Andrew DL Nelson) — Fri, 28 Mar 2025 00:00:00 +0000

Soil salinity is one of the major threats to agricultural productivity worldwide. Salt stress exposure alters root and shoots growth rates, thereby affecting overall plant performance. While past studies have extensively documented the effect of salt stress on root elongation and shoot development separately, here we take an innovative approach by examining the coordination of root and shoot growth under salt stress conditions. Utilizing a newly developed tool for quantifying the root:shoot ratio in agar-grown Arabidopsis seedlings, we found that salt stress results in a loss of coordination between root and shoot growth rates. We identify a specific gene cluster encoding domain-of-unknown-function 247 (DUF247), and characterize one of these genes as Salt Root:shoot Ratio Regulator Gene (SR3G). Further analysis elucidates the role of SR3G as a negative regulator of salt stress tolerance, revealing its function in regulating shoot growth, root suberization, and sodium accumulation. We further characterize that SR3G expression is modulated by WRKY75 transcription factor, known as a positive regulator of salt stress tolerance. Finally, we show that the salt stress sensitivity of wrky75 mutant is completely diminished when it is combined with sr3g mutation. Together, our results demonstrate that utilizing root:shoot ratio as an architectural feature leads to the discovery of a new stress resilience gene. The study’s innovative approach and findings not only contribute to our understanding of plant stress tolerance mechanisms but also open new avenues for genetic and agronomic strategies to enhance crop environmental resilience.

ATG6 interacting with NPR1 increases Arabidopsis thaliana resistance to Pst DC3000/avrRps4 by increasing its nuclear accumulation and stability

zhoujun@scnu.edu.cn (Baihong Zhang) — Tue, 04 Mar 2025 00:00:00 +0000

Autophagy-related gene 6 (ATG6) plays a crucial role in plant immunity. Nonexpressor of pathogenesis-related genes 1 (NPR1) acts as a signaling hub of plant immunity. However, the relationship between ATG6 and NPR1 is unclear. Here, we find that ATG6 directly interacts with NPR1. ATG6 overexpression significantly increased nuclear accumulation of NPR1. Furthermore, we demonstrate that ATG6 increases NPR1 protein levels and improves its stability. Interestingly, ATG6 promotes the formation of SINCs (SA-induced NPR1 condensates)-like condensates. Additionally, ATG6 and NPR1 synergistically promote the expression of pathogenesis-related genes. Further results showed that silencing ATG6 in NPR1-GFP exacerbates Pst DC3000/avrRps4 infection, while double overexpression of ATG6 and NPR1 synergistically inhibits Pst DC3000/avrRps4 infection. In summary, our findings unveil an interplay of NPR1 with ATG6 and elucidate important molecular mechanisms for enhancing plant immunity.

Systems genomics of salinity stress response in rice

joly-lopez.zoe@uqam.ca (Andres Godwin C Sajise) — Thu, 20 Feb 2025 00:00:00 +0000

Populations can adapt to stressful environments through changes in gene expression. However, the fitness effect of gene expression in mediating stress response and adaptation remains largely unexplored. Here, we use an integrative field dataset obtained from 780 plants of Oryza sativa ssp. indica (rice) grown in a field experiment under normal or moderate salt stress conditions to examine selection and evolution of gene expression variation under salinity stress conditions. We find that salinity stress induces increased selective pressure on gene expression. Further, we show that trans-eQTLs rather than cis-eQTLs are primarily associated with rice’s gene expression under salinity stress, potentially via a few master-regulators. Importantly, and contrary to the expectations, we find that cis-trans reinforcement is more common than cis-trans compensation which may be reflective of rice diversification subsequent to domestication. We further identify genetic fixation as the likely mechanism underlying this compensation/reinforcement. Additionally, we show that cis- and trans-eQTLs are under balancing and purifying selection, respectively, giving us insights into the evolutionary dynamics of gene expression variation. By examining genomic, transcriptomic, and phenotypic variation across a rice population, we gain insights into the molecular and genetic landscape underlying adaptive salinity stress responses, which is relevant for other crops and other stresses.

Correction: Genome editing of an African elite rice variety confers resistance against endemic and emerging Xanthomonas oryzae pv. oryzae strains

Tue, 07 Jan 2025 00:00:00 +0000

The phytoplasma SAP54 effector acts as a molecular matchmaker for leafhopper vectors by targeting plant MADS-box factor SVP

zigmunds.orlovskis@biomed.lu.lv (Adi Kliot) — Tue, 07 Jan 2025 00:00:00 +0000

Obligate parasites often trigger significant changes in their hosts to facilitate transmission to new hosts. The molecular mechanisms behind these extended phenotypes - where genetic information of one organism is manifested as traits in another - remain largely unclear. This study explores the role of the virulence protein SAP54, produced by parasitic phytoplasmas, in attracting leafhopper vectors. SAP54 is responsible for the induction of leaf-like flowers in phytoplasma-infected plants. However, we previously demonstrated that the insects were attracted to leaves and the leaf-like flowers were not required. Here, we made the surprising discovery that leaf exposure to leafhopper males is required for the attraction phenotype, suggesting a leaf response that distinguishes leafhopper sex in the presence of SAP54. In contrast, this phytoplasma effector alongside leafhopper females discourages further female colonization. We demonstrate that SAP54 effectively suppresses biotic stress response pathways in leaves exposed to the males. Critically, the host plant MADS-box transcription factor short vegetative phase (SVP) emerges as a key element in the female leafhopper preference for plants exposed to males, with SAP54 promoting the degradation of SVP. This preference extends to female colonization of male-exposed svp null mutant plants over those not exposed to males. Our research underscores the dual role of the phytoplasma effector SAP54 in host development alteration and vector attraction - integral to the phytoplasma life cycle. Importantly, we clarify how SAP54, by targeting SVP, heightens leaf vulnerability to leafhopper males, thus facilitating female attraction and subsequent plant colonization by the insects. SAP54 essentially acts as a molecular ‘matchmaker’, helping male leafhoppers more easily locate mates by degrading SVP-containing complexes in leaves. This study not only provides insights into the long reach of single parasite genes in extended phenotypes, but also opens avenues for understanding how transcription factors that regulate plant developmental processes intersect with and influence plant-insect interactions.

Root cap cell corpse clearance limits microbial colonization in Arabidopsis thaliana

azuccaro@uni-koeln.de (Alga Zuccaro) — Tue, 12 Nov 2024 00:00:00 +0000

Programmed cell death occurring during plant development (dPCD) is a fundamental process integral for plant growth and reproduction. Here, we investigate the connection between developmentally controlled PCD and fungal accommodation in Arabidopsis thaliana roots, focusing on the root cap-specific transcription factor ANAC033/SOMBRERO (SMB) and the senescence-associated nuclease BFN1. Mutations of both dPCD regulators increase colonization by the beneficial fungus Serendipita indica, primarily in the differentiation zone. smb-3 mutants additionally exhibit hypercolonization around the meristematic zone and a delay of S. indica-induced root-growth promotion. This demonstrates that root cap dPCD and rapid post-mortem clearance of cellular corpses represent a physical defense mechanism restricting microbial invasion of the root. Additionally, reporter lines and transcriptional analysis revealed that BFN1 expression is downregulated during S. indica colonization in mature root epidermal cells, suggesting a transcriptional control mechanism that facilitates the accommodation of beneficial microbes in the roots.

Autophagosome development and chloroplast segmentation occur synchronously for piecemeal degradation of chloroplasts

masanori.izumi@riken.jp (Hiroyuki Ishida) — Thu, 07 Nov 2024 00:00:00 +0000

Plants distribute many nutrients to chloroplasts during leaf development and maturation. When leaves senesce or experience sugar starvation, the autophagy machinery degrades chloroplast proteins to facilitate efficient nutrient reuse. Here, we report on the intracellular dynamics of an autophagy pathway responsible for piecemeal degradation of chloroplast components. Through live-cell monitoring of chloroplast morphology, we observed the formation of chloroplast budding structures in sugar-starved leaves. These buds were then released and incorporated into the vacuolar lumen as an autophagic cargo termed a Rubisco-containing body. The budding structures did not accumulate in mutants of core autophagy machinery, suggesting that autophagosome creation is required for forming chloroplast buds. Simultaneous tracking of chloroplast morphology and autophagosome development revealed that the isolation membranes of autophagosomes interact closely with part of the chloroplast surface before forming chloroplast buds. Chloroplasts then protrude at the site associated with the isolation membranes, which divide synchronously with autophagosome maturation. This autophagy-related division does not require DYNAMIN-RELATED PROTEIN 5B, which constitutes the division ring for chloroplast proliferation in growing leaves. An unidentified division machinery may thus fragment chloroplasts for degradation in coordination with the development of the chloroplast-associated isolation membrane.

Structural basis for molecular assembly of fucoxanthin chlorophyll a/c-binding proteins in a diatom photosystem I supercomplex

shen@cc.okayama-u.ac.jp (Haruya Ogawa) — Thu, 31 Oct 2024 00:00:00 +0000

Photosynthetic organisms exhibit remarkable diversity in their light-harvesting complexes (LHCs). LHCs are associated with photosystem I (PSI), forming a PSI-LHCI supercomplex. The number of LHCI subunits, along with their protein sequences and pigment compositions, has been found to differ greatly among the PSI-LHCI structures. However, the mechanisms by which LHCIs recognize their specific binding sites within the PSI core remain unclear. In this study, we determined the cryo-electron microscopy structure of a PSI supercomplex incorporating fucoxanthin chlorophyll a/c-binding proteins (FCPs), designated as PSI-FCPI, isolated from the diatom Thalassiosira pseudonana CCMP1335. Structural analysis of PSI-FCPI revealed five FCPI subunits associated with a PSI monomer; these subunits were identified as RedCAP, Lhcr3, Lhcq10, Lhcf10, and Lhcq8. Through structural and sequence analyses, we identified specific protein–protein interactions at the interfaces between FCPI and PSI subunits, as well as among FCPI subunits themselves. Comparative structural analyses of PSI-FCPI supercomplexes, combined with phylogenetic analysis of FCPs from T. pseudonana and the diatom Chaetoceros gracilis, underscore the evolutionary conservation of protein motifs crucial for the selective binding of individual FCPI subunits. These findings provide significant insights into the molecular mechanisms underlying the assembly and selective binding of FCPIs in diatoms.

Root-specific theanine metabolism and regulation at the single-cell level in tea plants (Camellia sinensis)

zhlzhang@ahau.edu.cn (Biying Zhu) — Mon, 14 Oct 2024 00:00:00 +0000

Root-synthesized secondary metabolites are critical quality-conferring compounds of foods, plant-derived medicines, and beverages. However, information at a single-cell level on root-specific secondary metabolism remains largely unexplored. L-Theanine, an important quality component of tea, is primarily synthesized in roots, from which it is then transported to new shoots of tea plant. In this study, we present a single-cell RNA sequencing (scRNA-seq)-derived map for the tea plant root, which enabled cell-type-specific analysis of glutamate and ethylamine (two precursors of theanine biosynthesis) metabolism, and theanine biosynthesis, storage, and transport. Our findings support a model in which the theanine biosynthesis pathway occurs via multicellular compartmentation and does not require high co-expression levels of transcription factors and their target genes within the same cell cluster. This study provides novel insights into theanine metabolism and regulation, at the single-cell level, and offers an example for studying root-specific secondary metabolism in other plant systems.

Pectin methylesterase activity is required for RALF1 peptide signalling output

elke.barbez@cibss.uni-freiburg.de (Ann-Kathrin Rößling) — Thu, 03 Oct 2024 00:00:00 +0000

The extracellular matrix plays an integrative role in cellular responses in plants, but its contribution to the signalling of extracellular ligands largely remains to be explored. Rapid alkalinisation factors (RALFs) are extracellular peptide hormones that play pivotal roles in various physiological processes. Here, we address a crucial connection between the de-methylesterification machinery of the cell wall component pectin and RALF1 activity. Pectin is a polysaccharide, contributing to the structural integrity of the cell wall. Our data illustrate that the pharmacological and genetic interference with pectin methyl esterases (PMEs) abolishes RALF1-induced root growth repression. Our data suggest that positively charged RALF1 peptides bind negatively charged, de-methylesterified pectin with high avidity. We illustrate that the RALF1 association with de-methylesterified pectin is required for its FERONIA-dependent perception, contributing to the control of the extracellular matrix and the regulation of plasma membrane dynamics. Notably, this mode of action is independent of the FER-dependent extracellular matrix sensing mechanism provided by FER interaction with the leucine-rich repeat extensin (LRX) proteins. We propose that the methylation status of pectin acts as a contextualizing signalling scaffold for RALF peptides, linking extracellular matrix dynamics to peptide hormone-mediated responses.

Structure and evolution of alanine/serine decarboxylases and the engineering of theanine production

wgong@ustc.edu.cn (Biying Zhu) — Tue, 17 Sep 2024 00:00:00 +0000

Ethylamine (EA), the precursor of theanine biosynthesis, is synthesized from alanine decarboxylation by alanine decarboxylase (AlaDC) in tea plants. AlaDC evolves from serine decarboxylase (SerDC) through neofunctionalization and has lower catalytic activity. However, lacking structure information hinders the understanding of the evolution of substrate specificity and catalytic activity. In this study, we solved the X-ray crystal structures of AlaDC from Camellia sinensis (CsAlaDC) and SerDC from Arabidopsis thaliana (AtSerDC). Tyr³⁴¹ of AtSerDC or the corresponding Tyr³³⁶ of CsAlaDC is essential for their enzymatic activity. Tyr¹¹¹ of AtSerDC and the corresponding Phe¹⁰⁶ of CsAlaDC determine their substrate specificity. Both CsAlaDC and AtSerDC have a distinctive zinc finger and have not been identified in any other Group II PLP-dependent amino acid decarboxylases. Based on the structural comparisons, we conducted a mutation screen of CsAlaDC. The results indicated that the mutation of L110F or P114A in the CsAlaDC dimerization interface significantly improved the catalytic activity by 110% and 59%, respectively. Combining a double mutant of CsAlaDC^L110F/P114A with theanine synthetase increased theanine production 672% in an in vitro system. This study provides the structural basis for the substrate selectivity and catalytic activity of CsAlaDC and AtSerDC and provides a route to more efficient biosynthesis of theanine.

OsNF-YB7 inactivates OsGLK1 to inhibit chlorophyll biosynthesis in rice embryo

chenchen@yzu.edu.cn (Baixiao Niu) — Tue, 17 Sep 2024 00:00:00 +0000

As a master regulator of seed development, Leafy Cotyledon 1 (LEC1) promotes chlorophyll (Chl) biosynthesis in Arabidopsis, but the mechanism underlying this remains poorly understood. Here, we found that loss of function of OsNF-YB7, a LEC1 homolog of rice, leads to chlorophyllous embryo, indicating that OsNF-YB7 plays an opposite role in Chl biosynthesis in rice compared with that in Arabidopsis. OsNF-YB7 regulates the expression of a group of genes responsible for Chl biosynthesis and photosynthesis by directly binding to their promoters. In addition, OsNF-YB7 interacts with Golden 2-Like 1 (OsGLK1) to inhibit the transactivation activity of OsGLK1, a key regulator of Chl biosynthesis. Moreover, OsNF-YB7 can directly repress OsGLK1 expression by recognizing its promoter in vivo, indicating the involvement of OsNF-YB7 in multiple regulatory layers of Chl biosynthesis in rice embryo. We propose that OsNF-YB7 functions as a transcriptional repressor to regulate Chl biosynthesis in rice embryo.