bluuebunny/crossref_metadata_2025 huggingface dataset:
A selanylimidazopyridine (3-SePh-IP) reverses the prodepressant- and anxiogenic-like effects of a high-fat/high-fructose diet in mice
Authors: Veloso Izolene Corrêa , Delanogare Eslen , Machado Adriano Emanuel , Braga Sara Pereira , Rosa Giovana Karoline , De Bem Andreza Fabro , Rafique Jamal , Saba Sumbal , da Trindade Roberth Nascimento , Galetto Fábio Zazyki , Moreira Eduardo Luiz Gasnhar
Published: January 2021

Objective

While chronic feeding with high-fat or high-sugar diets is known related to obesity and type 2 diabetes, later data have indicated that it is also related to depression and anxiety appearance. In this regard, multi-target drugs raise considerable interest as promising therapeutic solutions to complex diseases. Considering the pharmacological effects of the imidazopyridine-derivative moiety imidazo[1,2-a]pyridine and the organoselenium molecules, the combination of both could be a feasible strategy to develop efficient drugs to handle obesity and related comorbidities, for example dyslipidemia and mood disorders.

Methods

The antidepressant- and anxiolytic-like properties of a selanylimidazopyridine compound, 2-Phenyl-3-(phenylselanyl)imidazo[1,2-a]pyridine (3-SePh-IP), were evaluated on high-fat/high-fructose diet (HFFD)-fed female Swiss mice.

Key findings

Our results showed that a short-term HFFD (16 days) could promote a significant body weight gain, hypercholesterolemia, glucose intolerance, and anxiety- and depressive-like behaviour in mice. Concomitant treatment with 3-SePh-IP (10 mg/kg; i.p.) attenuated the HFFD-induced increase in cholesterol levels and blunted the anxiety- and depressive-like behaviour in mice.

Conclusions

3-SePh-IP holds multimodal pharmacological properties, which provide a rationale for further studies, for example to assess the underlying mechanisms linked to its anxiolytic- and antidepressive-like activities.
The Hague Child Abduction Convention and Re-relocation Disputes
Authors: Schuz Rhona
Published: January 2021

It is widely recognized that the 1980 Hague Convention on the Civil Aspects of International Child Abduction ('the Convention') is invoked in types of cases which were not envisioned by the drafters and which might not naturally be classified as abduction cases. This article provides detailed consideration of one such type of case, which will be referred to as "re-relocation disputes." Such disputes arise when, following a temporary/ conditional move or a recent permanent move to a 'new' country, one parent wishes to return to the 'base' country', while the other insists on staying in the new country. The purpose of this article is to consider the impact and policy implications of using the Convention's mandatory return mechanism to resolve these disputes. Reframing these situations as re-relocation disputes facilitates analysis of the phenomenon from a broader perspective, including consideration of tools designed to create certainty and to produce result consistent with policy objectives. This discussion is particularly timely in the light of global jurisprudential developments over the last few years in relation to the test for determining the child's habitual residence and the implications of the recent decision of the English Court of Appeal in the case of Re NY[2019]UKSC 49 for consensual removals or retentions.
Infalling thermally destroyed bodies as a possible explanation for the KIC 8462852 phenomenon
Authors: Shestakova Lyubov I , Serebryanskiy Aleksander V , Demchenko Boris I
Published: January 2021

Using the analytical solution of the heat diffusion equation, we calculate the components of the thermal stress tensor and analyse the process of thermal destruction of bodies consisting of crystalline ice with radii ranging from 10 m to 10 km around KIC 8462852. As a body approaches the star in a high-eccentricity orbit, compressive stresses increase on its surface, making tensile stresses increase in its interior and causing catastrophic body destruction. The processes of destruction near the surface of bodies that occur as a result of compressive stress and contribute to the appearance of coma are most severe in large bodies (10 km or more). We show that, for bodies with radii from 20 m to 10 km, internal tensile strengths exceed the limit of material strength at different distances from the star. Bodies with a size of r ≈ 1.8–2.1 km are among the first to experience catastrophic destruction, being at a distance of 80–100 au from the star. Subsequent cascading destruction of fragments can lead to the formation of dust. Closest to the star, being at a distance of 7.44 au, both the biggest and smallest bodies with a radius of more than 10 km and less than 20 m, respectively, begin to break apart. The infalling thermally destroyed body (ITDB) mechanism is capable of explaining the main details of both the short-term and long-term photometric behaviour of KIC 8462852.
A set of orbital elements to fully represent the zonal harmonics around an oblate celestial body
Authors: Arnas David , Linares Richard
Published: January 2021

This work introduces a new set of orbital elements to fully represent the zonal harmonics problem around an oblate celestial body. This new set of orbital elements allows to obtain a linear system for the unperturbed problem and, in addition, a completely polynomial system when considering the perturbation produced by the zonal harmonics from the gravitational force of an oblate celestial body. These orbital elements present no singularities and are able to represent any kind of orbit, including elliptic, parabolic, and hyperbolic orbits. Moreover, an application to this formulation of the Poincaré–Lindstedt perturbation method is included to obtain an approximate first-order solution of the problem for the case of the J2 perturbation, showing the performance of the methodology for different kinds of orbits.
Reproducing submillimetre galaxy number counts with cosmological hydrodynamic simulations
Authors: Lovell Christopher C , Geach James E , Davé Romeel , Narayanan Desika , Li Qi
Published: January 2021

Matching the number counts of high-z submillimetre-selected galaxies (SMGs) has been a long-standing problem for galaxy formation models. In this paper, we use 3D dust radiative transfer to model the submm emission from galaxies in the simba cosmological hydrodynamic simulations, and compare predictions to the latest single-dish observational constraints on the abundance of 850 μm-selected sources. We find good agreement with the shape of the integrated 850 μm luminosity function, and the normalization is within 0.25 dex at >3 mJy, unprecedented for a fully cosmological hydrodynamic simulation, along with good agreement in the redshift distribution of bright SMGs. The agreement is driven primarily by simba’s good match to infrared measures of the star formation rate (SFR) function between z = 2 and 4 at high SFRs. Also important is the self-consistent on-the-fly dust model in simba, which predicts, on average, higher dust masses (by up to a factor of 2.5) compared to using a fixed dust-to-metals ratio of 0.3. We construct a light-cone to investigate the effect of far-field blending, and find that 52 per cent of sources are blends of multiple components, which makes a small contribution to the normalization of the bright end of the number counts. We provide new fits to the 850 μm luminosity as a function of SFR and dust mass. Our results demonstrate that solutions to the discrepancy between submm counts in simulations and observations, such as a top-heavy initial mass function, are unnecessary, and that submillimetre-bright phases are a natural consequence of massive galaxy evolution.
Comprehensibility and Accountability
Authors: Shapira Roy
Published: January 2021

In Incomprehensible!, Wendy Wagner highlights a blind spot in the design of many legal programmes: they demand that market players share as much information as possible, but neglect to demand that the information be conveyed comprehensibly. Wagner shows how the neglect of comprehensibility undermines the law’s effectiveness, and provides a menu of concrete proposals for alleviating it. Yet Wagner’s analysis leaves one important question unanswered: will making information more comprehensible necessarily lead to more accountability and better policy outcomes? This review article examines the elusive link between comprehensibility and accountability, and spotlights four common scenarios whereby the former is not a sufficient or even a necessary condition for the latter. In some markets, we have accountability without comprehensibility, through the threat of reputational sanctions. In others, we have comprehensibility without accountability: disclosures are perfectly readable, yet the end users opt not to read them. A third scenario is where more comprehensibility actually leads to less accountability: top-down mandates of comprehensibility crowd out efforts by private intermediaries to process complex information. Finally, there are circumstances where comprehensibility leads to too much accountability: in certain trade-offs, more accountability leads to worse decision making.
DEAD-BOX RNA HELICASE 27 regulates microRNA biogenesis, zygote division, and stem cell homeostasis
Authors: Hou Xiu-Li , Chen Wen-Qiang , Hou Yifeng , Gong Hua-Qin , Sun Jing , Wang Zhen , Zhao Heng , Cao Xiaofeng , Song Xiu-Fen , Liu Chun-Ming
Published: January 2021

After double fertilization, zygotic embryogenesis initiates a new life cycle, and stem cell homeostasis in the shoot apical meristem (SAM) and root apical meristem (RAM) allows plants to produce new tissues and organs continuously. Here, we report that mutations in DEAD-BOX RNA HELICASE 27 (RH27) affect zygote division and stem cell homeostasis in Arabidopsis (Arabidopsis thaliana). The strong mutant allele rh27-1 caused a zygote-lethal phenotype, while the weak mutant allele rh27-2 led to minor defects in embryogenesis and severely compromised stem cell homeostasis in the SAM and RAM. RH27 is expressed in embryos from the zygote stage, and in both the SAM and RAM, and RH27 is a nucleus-localized protein. The expression levels of genes related to stem cell homeostasis were elevated in rh27-2 plants, alongside down-regulation of their regulatory microRNAs (miRNAs). Further analyses of rh27-2 plants revealed reduced levels of a large subset of miRNAs and their pri-miRNAs in shoot apices and root tips. In addition, biochemical studies showed that RH27 associates with pri-miRNAs and interacts with miRNA-biogenesis components, including DAWDLE, HYPONASTIC LEAVES 1, and SERRATE. Therefore, we propose that RH27 is a component of the microprocessor complex and is critical for zygote division and stem cell homeostasis.
Plant NLR diversity: the known unknowns of pan-NLRomes
Authors: Barragan A Cristina , Weigel Detlef
Published: January 2021

Plants and pathogens constantly adapt to each other. As a consequence, many members of the plant immune system, and especially the intracellular nucleotide-binding site leucine-rich repeat receptors, also known as NOD-like receptors (NLRs), are highly diversified, both among family members in the same genome, and between individuals in the same species. While this diversity has long been appreciated, its true extent has remained unknown. With pan-genome and pan-NLRome studies becoming more and more comprehensive, our knowledge of NLR sequence diversity is growing rapidly, and pan-NLRomes provide powerful platforms for assigning function to NLRs. These efforts are an important step toward the goal of comprehensively predicting from sequence alone whether an NLR provides disease resistance, and if so, to which pathogens.
EDS1-interacting J protein 1 is an essential negative regulator of plant innate immunity in Arabidopsis
Authors: Liu Hailun , Li Yuge , Hu Yilong , Yang Yuhua , Zhang Wenbin , He Ming , Li Xiaoming , Zhang Chunyu , Kong Fanjiang , Liu Xu , Hou Xingliang
Published: January 2021

Plants have evolved precise mechanisms to optimize immune responses against pathogens. ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) plays a vital role in plant innate immunity by regulating basal resistance and effector-triggered immunity. Nucleocytoplasmic trafficking of EDS1 is required for resistance reinforcement, but the molecular mechanism remains elusive. Here, we show that EDS1-INTERACTING J PROTEIN1 (EIJ1), which acts as a DnaJ protein-like chaperone in response to pathogen infection, functions as an essential negative regulator of plant immunity by interacting with EDS1. The loss-of-function mutation of EIJ1 did not affect plant growth but significantly enhanced pathogen resistance. Upon pathogen infection, EIJ1 relocalized from the chloroplast to the cytoplasm, where it interacted with EDS1, thereby restricting pathogen-triggered trafficking of EDS1 to the nucleus and compromising resistance at an early infection stage. During disease development, EIJ1 was gradually degraded, allowing the nuclear accumulation of EDS1 for transcriptional resistance reinforcement. The avirulent strain Pst DC3000 (AvrRps4) abolished the repressive action of EIJ1 by rapidly inducing its degradation in the effector-triggered immunity response. Thus, our findings show that EIJ1 is an essential EDS1-dependent negative regulator of innate plant immunity and provide a mechanistic understanding of how the nuclear versus cytoplasmic distribution of EDS1 is regulated during the immune response.
The B3 domain-containing transcription factor ZmABI19 coordinates expression of key factors required for maize seed development and grain filling
Authors: Yang Tao , Guo Liangxing , Ji Chen , Wang Haihai , Wang Jiechen , Zheng Xixi , Xiao Qiao , Wu Yongrui
Published: January 2021

Grain filling in maize (Zea mays) is regulated by a group of spatiotemporally synchronized transcription factors (TFs), but the factors that coordinate their expression remain unknown. We used the promoter of the grain filling-specific TF gene Opaque2 (O2) to screen upstream regulatory factors and identified a B3 domain TF, ZmABI19, that directly binds to the O2 promoter for transactivation. zmabi19 mutants displayed developmental defects in the endosperm and embryo, and mature kernels were opaque and reduced in size. The accumulation of zeins, starch and lipids dramatically decreased in zmabi19 mutants. RNA sequencing revealed an alteration of the nutrient reservoir activity and starch and sucrose metabolism in zmabi19 endosperms, and plant phytohormone signal transduction and lipid metabolism in zmabi19 embryos. Chromatin immunoprecipitation followed by sequencing coupled with differential expression analysis identified 106 high-confidence direct ZmABI19 targets. ZmABI19 directly regulates multiple key grain filling TFs including O2, Prolamine-box binding factor 1, ZmbZIP22, NAC130, and Opaque11 in the endosperm and Viviparous1 in the embryo. A number of phytohormone-related genes were also bound and regulated by ZmABI19. Our results demonstrate that ZmABI19 functions as a grain filling initiation regulator. ZmABI19 roles in coupling early endosperm and embryo development are also discussed.
Spatial transcriptional signatures define margin morphogenesis along the proximal–distal and medio-lateral axes in tomato (Solanum lycopersicum) leaves
Authors: Martinez Ciera C , Li Siyu , Woodhouse Margaret R , Sugimoto Keiko , Sinha Neelima R
Published: January 2021

Leaf morphogenesis involves cell division, expansion, and differentiation in the developing leaf, which take place at different rates and at different positions along the medio-lateral and proximal–distal leaf axes. The gene expression changes that control cell fate along these axes remain elusive due to difficulties in precisely isolating tissues. Here, we combined rigorous early leaf characterization, laser capture microdissection, and transcriptomic sequencing to ask how gene expression patterns regulate early leaf morphogenesis in wild-type tomato (Solanum lycopersicum) and the leaf morphogenesis mutant trifoliate. We observed transcriptional regulation of cell differentiation along the proximal–distal axis and identified molecular signatures delineating the classically defined marginal meristem/blastozone region during early leaf development. We describe the role of endoreduplication during leaf development, when and where leaf cells first achieve photosynthetic competency, and the regulation of auxin transport and signaling along the leaf axes. Knockout mutants of BLADE-ON-PETIOLE2 exhibited ectopic shoot apical meristem formation on leaves, highlighting the role of this gene in regulating margin tissue identity. We mapped gene expression signatures in specific leaf domains and evaluated the role of each domain in conferring indeterminacy and permitting blade outgrowth. Finally, we generated a global gene expression atlas of the early developing compound leaf.
Seed-coat protective neolignans are produced by the dirigent protein AtDP1 and the laccase AtLAC5 in Arabidopsis
Authors: Yonekura-Sakakibara Keiko , Yamamura Masaomi , Matsuda Fumio , Ono Eiichiro , Nakabayashi Ryo , Sugawara Satoko , Mori Tetsuya , Tobimatsu Yuki , Umezawa Toshiaki , Saito Kazuki
Published: January 2021

Lignans/neolignans are generally synthesized from coniferyl alcohol (CA) in the cinnamate/monolignol pathway by oxidation to generate the corresponding radicals with subsequent stereoselective dimerization aided by dirigent proteins (DIRs). Genes encoding oxidases and DIRs for neolignan biosynthesis have not been identified previously. In Arabidopsis thaliana, the DIR AtDP1/AtDIR12 plays an essential role in the 8-O-4′ coupling in neolignan biosynthesis by unequivocal structural determination of the compound missing in the atdp1 mutant as a sinapoylcholine (SC)-conjugated neolignan, erythro-3-{4-[2-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-1-hydroxymethylethoxy]-3,5-dimethoxyphenyl}acryloylcholine. Phylogenetic analyses showed that AtDP1/AtDIR12 belongs to the DIR-a subfamily composed of DIRs for 8-8′ coupling of monolignol radicals. AtDP1/AtDIR12 is specifically expressed in outer integument 1 cells in developing seeds. As a putative oxidase for neolignan biosynthesis, we focused on AtLAC5, a laccase gene coexpressed with AtDP1/AtDIR12. In lac5 mutants, the abundance of feruloylcholine (FC)-conjugated neolignans decreased to a level comparable to those in the atdp1 mutant. In addition, SC/FC-conjugated neolignans were missing in the seeds of mutants defective in SCT/SCPL19, an enzyme that synthesizes SC. These results strongly suggest that AtDP1/AtDIR12 and AtLAC5 are involved in neolignan biosynthesis via SC/FC. A tetrazolium penetration assay showed that seed coat permeability increased in atdp1 mutants, suggesting a protective role of neolignans in A. thaliana seeds.
Polyploidy: an evolutionary and ecological force in stressful times
Authors: Van de Peer Yves , Ashman Tia-Lynn , Soltis Pamela S , Soltis Douglas E
Published: January 2021

Polyploidy has been hypothesized to be both an evolutionary dead-end and a source for evolutionary innovation and species diversification. Although polyploid organisms, especially plants, abound, the apparent nonrandom long-term establishment of genome duplications suggests a link with environmental conditions. Whole-genome duplications seem to correlate with periods of extinction or global change, while polyploids often thrive in harsh or disturbed environments. Evidence is also accumulating that biotic interactions, for instance, with pathogens or mutualists, affect polyploids differently than nonpolyploids. Here, we review recent findings and insights on the effect of both abiotic and biotic stress on polyploids versus nonpolyploids and propose that stress response in general is an important and even determining factor in the establishment and success of polyploidy.
Analysis of a photosynthetic cyanobacterium rich in internal membrane systems via gradient profiling by sequencing (Grad-seq)
Authors: Riediger Matthias , Spät Philipp , Bilger Raphael , Voigt Karsten , Maček Boris , Hess Wolfgang R
Published: January 2021

Although regulatory small RNAs have been reported in photosynthetic cyanobacteria, the lack of clear RNA chaperones involved in their regulation poses a conundrum. Here, we analyzed the full complement of cellular RNAs and proteins using gradient profiling by sequencing (Grad-seq) in Synechocystis 6803. Complexes with overlapping subunits such as the CpcG1-type versus the CpcL-type phycobilisomes or the PsaK1 versus PsaK2 photosystem I pre(complexes) could be distinguished, supporting the high quality of this approach. Clustering of the in-gradient distribution profiles followed by several additional criteria yielded a short list of potential RNA chaperones that include an YlxR homolog and a cyanobacterial homolog of the KhpA/B complex. The data suggest previously undetected complexes between accessory proteins and CRISPR-Cas systems, such as a Csx1-Csm6 ribonucleolytic defense complex. Moreover, the exclusive association of either RpoZ or 6S RNA with the core RNA polymerase complex and the existence of a reservoir of inactive sigma–antisigma complexes is suggested. The Synechocystis Grad-seq resource is available online at https://sunshine.biologie.uni-freiburg.de/GradSeqExplorer/ providing a comprehensive resource for the functional assignment of RNA–protein complexes and multisubunit protein complexes in a photosynthetic organism.
Gain-of-function of the 1-aminocyclopropane-1-carboxylate synthase geneACS1Ginduces female flower development in cucumber gynoecy
Authors: Zhang Huimin , Li Shuai , Yang Li , Cai Guanghua , Chen Huiming , Gao Dongli , Lin Tao , Cui Qingzhi , Wang Donghui , Li Zheng , Cai Run , Bai Shunong , Lucas William J , Huang Sanwen , Zhang Zhonghua , Sun Jinjing
Published: January 2021

Unisexual flowers provide a useful system for studying plant sex determination. In cucumber (Cucumis sativus L.), three major Mendelian loci control unisexual flower development, Female (F), androecious [a; 1-aminocyclopropane-1-carboxylate {ACC} synthase 11, acs11], and Monoecious (M; ACS2), referred to here as the Female, Androecious, Monoecious (FAM) model, in combination with two genes, gynoecious (g, the WIP family C2H2 zinc finger transcription factor gene WIP1) and the ethylene biosynthetic gene ACC oxidase 2 (ACO2). The F locus, conferring gynoecy and the potential for increasing fruit yield, is defined by a 30.2-kb tandem duplication containing three genes. However, the gene that determines the Female phenotype, and its mechanism, remains unknown. Here, we created a set of mutants and revealed that ACS1G is responsible for gynoecy conferred by the F locus. The duplication resulted in ACS1G acquiring a new promoter and expression pattern; in plants carrying the F locus duplication, ACS1G is expressed early in floral bud development, where it functions with ACO2 to generate an ethylene burst. The resulting ethylene represses WIP1 and activates ACS2 to initiate gynoecy. This early ACS1G expression bypasses the need for ACS11 to produce ethylene, thereby establishing a dominant pathway for female floral development. Based on these findings, we propose a model for how these ethylene biosynthesis genes cooperate to control unisexual flower development in cucumber.
Tissue-specific transcriptome profiling of the Arabidopsis inflorescence stem reveals local cellular signatures
Authors: Shi Dongbo , Jouannet Virginie , Agustí Javier , Kaul Verena , Levitsky Victor , Sanchez Pablo , Mironova Victoria V , Greb Thomas
Published: January 2021

Genome-wide gene expression maps with a high spatial resolution have substantially accelerated plant molecular science. However, the number of characterized tissues and growth stages is still small due to the limited accessibility of most tissues for protoplast isolation. Here, we provide gene expression profiles of the mature inflorescence stem of Arabidopsis thaliana covering a comprehensive set of distinct tissues. By combining fluorescence-activated nucleus sorting and laser-capture microdissection with next-generation RNA sequencing, we characterized the transcriptomes of xylem vessels, fibers, the proximal and distal cambium, phloem, phloem cap, pith, starch sheath, and epidermis cells. Our analyses classified more than 15,000 genes as being differentially expressed among different stem tissues and revealed known and novel tissue-specific cellular signatures. By determining overrepresented transcription factor binding regions in the promoters of differentially expressed genes, we identified candidate tissue-specific transcriptional regulators. Our datasets predict the expression profiles of an exceptional number of genes and allow hypotheses to be generated about the spatial organization of physiological processes. Moreover, we demonstrate that information about gene expression in a broad range of mature plant tissues can be established at high spatial resolution by nuclear mRNA profiling. Tissue-specific gene expression values can be accessed online at https://arabidopsis-stem.cos.uni-heidelberg.de/.
Transport-coupled ubiquitination of the borate transporter BOR1 for its boron-dependent degradation
Authors: Yoshinari Akira , Hosokawa Takuya , Beier Marcel Pascal , Oshima Keishi , Ogino Yuka , Hori Chiaki , Takasuka Taichi E , Fukao Yoichiro , Fujiwara Toru , Takano Junpei
Published: January 2021

Plants take up and translocate nutrients through transporters. In Arabidopsis thaliana, the borate exporter BOR1 acts as a key transporter under boron (B) limitation in the soil. Upon sufficient-B supply, BOR1 undergoes ubiquitination and is transported to the vacuole for degradation, to avoid overaccumulation of B. However, the mechanisms underlying B-sensing and ubiquitination of BOR1 are unknown. In this study, we confirmed the lysine-590 residue in the C-terminal cytosolic region of BOR1 as the direct ubiquitination site and showed that BOR1 undergoes K63-linked polyubiquitination. A forward genetic screen identified that amino acid residues located in vicinity of the substrate-binding pocket of BOR1 are essential for the vacuolar sorting. BOR1 variants that lack B-transport activity showed a significant reduction of polyubiquitination and subsequent vacuolar sorting. Coexpression of wild-type (WT) and a transport-defective variant of BOR1 in the same cells showed degradation of the WT but not the variant upon sufficient-B supply. These findings suggest that polyubiquitination of BOR1 relies on its conformational transition during the transport cycle. We propose a model in which BOR1, as a B transceptor, directly senses the B concentration and promotes its own polyubiquitination and vacuolar sorting for quick and precise maintenance of B homeostasis.
Contrasting transcriptional responses toFusarium virguliformecolonization in symptomatic and asymptomatic hosts
Authors: Baetsen-Young Amy , Chen Huan , Shiu Shin-Han , Day Brad
Published: January 2021

The broad host range of Fusarium virguliforme represents a unique comparative system to identify and define differentially induced responses between an asymptomatic monocot host, maize (Zea mays), and a symptomatic eudicot host, soybean (Glycine max). Using a temporal, comparative transcriptome-based approach, we observed that early gene expression profiles of root tissue from infected maize suggest that pathogen tolerance coincides with the rapid induction of senescence dampening transcriptional regulators, including ANACs (Arabidopsis thaliana NAM/ATAF/CUC protein) and Ethylene-Responsive Factors. In contrast, the expression of senescence-associated processes in soybean was coincident with the appearance of disease symptom development, suggesting pathogen-induced senescence as a key pathway driving pathogen susceptibility in soybean. Based on the analyses described herein, we posit that root senescence is a primary contributing factor underlying colonization and disease progression in symptomatic versus asymptomatic host–fungal interactions. This process also supports the lifestyle and virulence of F. virguliforme during biotrophy to necrotrophy transitions. Further support for this hypothesis lies in comprehensive co-expression and comparative transcriptome analyses, and in total, supports the emerging concept of necrotrophy-activated senescence. We propose that F. virguliforme conditions an environment within symptomatic hosts, which favors susceptibility through transcriptomic reprogramming, and as described herein, the induction of pathways associated with senescence during the necrotrophic stage of fungal development.
Exocyst subunit Exo70B2 is linked to immune signaling and autophagy
Authors: Brillada Carla , Teh Ooi-Kock , Ditengou Franck Anicet , Lee Chil-Woo , Klecker Till , Saeed Bushra , Furlan Giulia , Zietz Marco , Hause Gerd , Eschen-Lippold Lennart , Hoehenwarter Wolfgang , Lee Justin , Ott Thomas , Trujillo Marco
Published: January 2021

During the immune response, activation of the secretory pathway is key to mounting an effective response, while gauging its output is important to maintain cellular homeostasis. The Exo70 subunit of the exocyst functions as a spatiotemporal regulator by mediating numerous interactions with proteins and lipids. However, a molecular understanding of the exocyst regulation remains challenging. We show that, in Arabidopsis thaliana, Exo70B2 behaves as a bona fide exocyst subunit. Conversely, treatment with the salicylic acid (SA) defence hormone analog benzothiadiazole (BTH), or the immunogenic peptide flg22, induced Exo70B2 transport into the vacuole. We reveal that Exo70B2 interacts with AUTOPHAGY-RELATED PROTEIN 8 (ATG8) via two ATG8-interacting motives (AIMs) and its transport into the vacuole is dependent on autophagy. In line with its role in immunity, we discovered that Exo70B2 interacted with and was phosphorylated by the kinase MPK3. Mimicking phosphorylation had a dual impact on Exo70B2: first, by inhibiting localization at sites of active secretion, and second, it increased the interaction with ATG8. Phosphonull variants displayed higher effector-triggered immunity (ETI) and were hypersensitive to BTH, which induce secretion and autophagy. Our results suggest a molecular mechanism by which phosphorylation diverts Exo70B2 from the secretory into the autophagy pathway for its degradation, to dampen secretory activity.
Interdependent evolution of biosynthetic gene clusters for momilactone production in rice
Authors: Kitaoka Naoki , Zhang Juan , Oyagbenro Richard K , Brown Benjamin , Wu Yisheng , Yang Bing , Li Zhaohu , Peters Reuben J
Published: January 2021

Plants can contain biosynthetic gene clusters (BGCs) that nominally resemble those found in microbes. However, while horizontal gene transmission is often observed in microbes, plants are limited to vertical gene transmission, implying that their BGCs may exhibit distinct inheritance patterns. Rice (Oryza sativa) contains two unlinked BGCs involved in diterpenoid phytoalexin metabolism, with one clearly required for momilactone biosynthesis, while the other is associated with production of phytocassanes. Here, in the process of elucidating momilactone biosynthesis, genetic evidence was found demonstrating a role for a cytochrome P450 (CYP) from the other “phytocassane” BGC. This CYP76M8 acts after the CYP99A2/3 from the “momilactone” BGC, producing a hemiacetal intermediate that is oxidized to the eponymous lactone by a short-chain alcohol dehydrogenase also from this BGC. Thus, the “momilactone” BGC is not only incomplete, but also fractured by the need for CYP76M8 to act in between steps catalyzed by enzymes from this BGC. Moreover, as supported by similar activity observed with orthologs from the momilactone-producing wild-rice species Oryza punctata, the presence of CYP76M8 in the other “phytocassane” BGC indicates interdependent evolution of these two BGCs, highlighting the distinct nature of BGC assembly in plants.
Pod shattering in grain legumes: emerging genetic and environment-related patterns
Authors: Parker Travis A , Lo Sassoum , Gepts Paul
Published: January 2021

A reduction in pod shattering is one of the main components of grain legume domestication. Despite this, many domesticated legumes suffer serious yield losses due to shattering, particularly under arid conditions. Mutations related to pod shattering modify the twisting force of pod walls or the structural strength of the dehiscence zone in pod sutures. At a molecular level, a growing body of evidence indicates that these changes are controlled by a relatively small number of key genes that have been selected in parallel across grain legume species, supporting partial molecular convergence. Legume homologs of Arabidopsis thaliana silique shattering genes play only minor roles in legume pod shattering. Most domesticated grain legume species contain multiple shattering-resistance genes, with mutants of each gene typically showing only partial shattering resistance. Hence, crosses between varieties with different genes lead to transgressive segregation of shattering alleles, producing plants with either enhanced shattering resistance or atavistic susceptibility to the trait. The frequency of these resistance pod-shattering alleles is often positively correlated with environmental aridity. The continued development of pod-shattering-related functional information will be vital for breeding crops that are suited to the increasingly arid conditions expected in the coming decades.
Two interacting ethylene response factors regulate heat stress response
Authors: Huang Jianyan , Zhao Xiaobo , Bürger Marco , Wang Yurong , Chory Joanne
Published: January 2021

The ethylene response factor (ERF) transcription factors are integral components of environmental stress signaling cascades, regulating a wide variety of downstream genes related to stress responses and plant development. However, the mechanisms by which ERF genes regulate the heat stress response are not well understood. Here, we uncover the positive role of ethylene signaling, ERF95 and ERF97 in basal thermotolerance of Arabidopsis thaliana. We demonstrate that ethylene signaling-defective mutants exhibit compromised basal thermotolerance, whereas plants with constitutively activated ethylene response show enhanced basal thermotolerance. EIN3 physically binds to the promoters of ERF95 and ERF97. Ectopic constitutive expression of ERF95 or ERF97 increases the basal thermotolerance of plants. In contrast, erf95 erf96 erf97 erf98 quadruple mutants exhibit decreased basal thermotolerance. ERF95 and ERF97 genetically function downstream of EIN3. ERF95 can physically interact with ERF97, and this interaction is heat inducible. ERF95 and ERF97 regulate a common set of target genes, including known heat-responsive genes and directly bind to the promoter of HSFA2. Thus, our study reveals that the EIN3-ERF95/ERF97-HSFA2 transcriptional cascade may play an important role in the heat stress response, thereby establishing a connection between ethylene and its downstream regulation in basal thermotolerance of plants.
H3.1K27me1 maintains transcriptional silencing and genome stability by preventing GCN5-mediated histone acetylation
Authors: Dong Jie , LeBlanc Chantal , Poulet Axel , Mermaz Benoit , Villarino Gonzalo , Webb Kimberly M , Joly Valentin , Mendez Josefina , Voigt Philipp , Jacob Yannick
Published: January 2021

Epigenetic mechanisms play diverse roles in the regulation of genome stability in eukaryotes. In Arabidopsis thaliana, genome stability is maintained during DNA replication by the H3.1K27 methyltransferases ARABIDOPSIS TRITHORAX-RELATED PROTEIN 5 (ATXR5) and ATXR6, which catalyze the deposition of K27me1 on replication-dependent H3.1 variants. The loss of H3.1K27me1 in atxr5 atxr6 double mutants leads to heterochromatin defects, including transcriptional de-repression and genomic instability, but the molecular mechanisms involved remain largely unknown. In this study, we identified the transcriptional co-activator and conserved histone acetyltransferase GCN5 as a mediator of transcriptional de-repression and genomic instability in the absence of H3.1K27me1. GCN5 is part of a SAGA-like complex in plants that requires the GCN5-interacting protein ADA2b and the chromatin remodeler CHR6 to mediate the heterochromatic defects in atxr5 atxr6 mutants. Our results also indicate that Arabidopsis GCN5 acetylates multiple lysine residues on H3.1 variants, but H3.1K27 and H3.1K36 play essential functions in inducing genomic instability in the absence of H3.1K27me1. Finally, we show that H3.1K36 acetylation by GCN5 is negatively regulated by H3.1K27me1 in vitro. Overall, this work reveals a key molecular role for H3.1K27me1 in maintaining transcriptional silencing and genome stability in heterochromatin by restricting GCN5-mediated histone acetylation in plants.
EIN2-directed histone acetylation requires EIN3-mediated positive feedback regulation in response to ethylene
Authors: Wang Likai , Zhang Zhiyuan , Zhang Fan , Shao Zhengyao , Zhao Bo , Huang Austin , Tran Jaclyn , Hernandez Fernando Vera , Qiao Hong
Published: January 2021

Ethylene is an important phytohormone with pleotropic roles in plant growth, development, and stress responses. ETHYLENE INSENSITIVE2 (EIN2) mediates the transduction of the ethylene signal from the endoplasmic reticulum membrane to the nucleus, where its C-terminus (EIN2-C) regulates histone acetylation to mediate transcriptional regulation by EIN3. However, no direct interaction between EIN2-C and EIN3 has been detected. To determine how EIN2-C and EIN3 act together, we followed a synthetic approach and engineered a chimeric EIN2-C with EIN3 DNA-binding activity but lacking its transactivation activity (EIN2C–EIN3DB). The overexpression of EIN2C–EIN3DB in either wild-type or in the ethylene-insensitive mutant ein3-1 eil1-1 led to a partial constitutive ethylene response. Chromatin immunoprecipitation sequencing showed that EIN2C–EIN3DB has DNA-binding activity, indicating that EIN3DB is functional in EIN2C–EIN3DB. Furthermore, native EIN3 protein levels determine EIN2C–EIN3DB binding activity and binding targets in a positive feedback loop by interacting with EIN2C–EIN3DB to form a heterodimer. Additionally, although EIN3 does not direct affect histone acetylation levels in the absence of EIN2, it is required for the ethylene-induced elevation of H3K14Ac and H3K23Ac in the presence of EIN2. Together, we reveal efficient and specific DNA-binding by dimerized EIN3 in the presence of ethylene to mediate positive feedback regulation, which is required for EIN2-directed elevation of histone acetylation to integrate into an EIN3-dependent transcriptional activation.
Inverse regulation of light harvesting and photoprotection is mediated by a 3′-end-derived sRNA in cyanobacteria
Authors: Zhan Jiao , Steglich Claudia , Scholz Ingeborg , Hess Wolfgang R , Kirilovsky Diana
Published: January 2021

Phycobilisomes (PBSs), the principal cyanobacterial antenna, are among the most efficient macromolecular structures in nature, and are used for both light harvesting and directed energy transfer to the photosynthetic reaction center. However, under unfavorable conditions, excess excitation energy needs to be rapidly dissipated to avoid photodamage. The orange carotenoid protein (OCP) senses light intensity and induces thermal energy dissipation under stress conditions. Hence, its expression must be tightly controlled; however, the molecular mechanism of this regulation remains to be elucidated. Here, we describe the discovery of a posttranscriptional regulatory mechanism in Synechocystis sp. PCC 6803 in which the expression of the operon encoding the allophycocyanin subunits of the PBS is directly and in an inverse fashion linked to the expression of OCP. This regulation is mediated by ApcZ, a small regulatory RNA that is derived from the 3′-end of the tetracistronic apcABC–apcZ operon. ApcZ inhibits ocp translation under stress-free conditions. Under most stress conditions, apc operon transcription decreases and ocp translation increases. Thus, a key operon involved in the collection of light energy is functionally connected to the expression of a protein involved in energy dissipation. Our findings support the view that regulatory RNA networks in bacteria evolve through the functionalization of mRNA 3′-UTRs.
ERF4 and MYB52 transcription factors play antagonistic roles in regulating homogalacturonan de-methylesterification in Arabidopsis seed coat mucilage
Authors: Ding Anming , Tang Xianfeng , Yang Dahai , Wang Meng , Ren Angyan , Xu Zongchang , Hu Ruibo , Zhou Gongke , O’Neill Malcolm , Kong Yingzhen
Published: January 2021

Homogalacturonan (HG), a component of pectin, is synthesized in the Golgi apparatus in its fully methylesterified form. It is then secreted into the apoplast where it is typically de-methylesterified by pectin methylesterases (PME). Secretion and de-esterification are critical for normal pectin function, yet the underlying transcriptional regulation mechanisms remain largely unknown. Here, we uncovered a mechanism that fine-tunes the degree of HG de-methylesterification (DM) in the mucilage that surrounds Arabidopsis thaliana seeds. We demonstrate that the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factor (TF) ERF4 is a transcriptional repressor that positively regulates HG DM. ERF4 expression is confined to epidermal cells in the early stages of seed coat development. The adhesiveness of the erf4 mutant mucilage was decreased as a result of an increased DM caused by a decrease in PME activity. Molecular and genetic analyses revealed that ERF4 positively regulates HG DM by suppressing the expression of three PME INHIBITOR genes (PMEIs) and SUBTILISIN-LIKE SERINE PROTEASE 1.7 (SBT1.7). ERF4 shares common targets with the TF MYB52, which also regulates pectin DM. Nevertheless, the erf4-2 myb52 double mutant seeds have a wild-type mucilage phenotype. We provide evidence that ERF4 and MYB52 regulate downstream gene expression in an opposite manner by antagonizing each other’s DNA-binding ability through a physical interaction. Together, our findings reveal that pectin DM in the seed coat is fine-tuned by an ERF4–MYB52 transcriptional complex.
Plasma membrane nano-organization specifies phosphoinositide effects on Rho-GTPases and actin dynamics in tobacco pollen tubes
Authors: Fratini Marta , Krishnamoorthy Praveen , Stenzel Irene , Riechmann Mara , Matzner Monique , Bacia Kirsten , Heilmann Mareike , Heilmann Ingo
Published: January 2021

Pollen tube growth requires coordination of cytoskeletal dynamics and apical secretion. The regulatory phospholipid phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) is enriched in the subapical plasma membrane of pollen tubes of Arabidopsis thaliana and tobacco (Nicotiana tabacum) and can influence both actin dynamics and secretion. How alternative PtdIns(4,5)P2 effects are specified is unclear. In tobacco pollen tubes, spinning disc microscopy (SD) reveals dual distribution of a fluorescent PtdIns(4,5)P2-reporter in dynamic plasma membrane nanodomains vs. apparent diffuse membrane labeling, consistent with spatially distinct coexisting pools of PtdIns(4,5)P2. Several PI4P 5-kinases (PIP5Ks) can generate PtdIns(4,5)P2 in pollen tubes. Despite localizing to one membrane region, the PIP5Ks AtPIP5K2-EYFP and NtPIP5K6-EYFP display distinctive overexpression effects on cell morphologies, respectively related to altered actin dynamics or membrane trafficking. When analyzed by SD, AtPIP5K2-EYFP associated with nanodomains, whereas NtPIP5K6-EYFP localized diffusely. Chimeric AtPIP5K2-EYFP and NtPIP5K6-EYFP variants with reciprocally swapped membrane-associating domains evoked reciprocally shifted effects on cell morphology upon overexpression. Overall, active PI4P 5-kinase variants stabilized actin when targeted to nanodomains, suggesting a role of nanodomain-associated PtdIns(4,5)P2 in actin regulation. This notion is further supported by interaction and proximity of nanodomain-associated AtPIP5K2 with the Rho-GTPase NtRac5, and by its functional interplay with elements of Rho of plants signaling. Plasma membrane nano-organization may thus aid the specification of PtdIns(4,5)P2 functions to coordinate cytoskeletal dynamics and secretion.
Live imaging of microtubule organization, cell expansion, and intercellular space formation in Arabidopsis leaf spongy mesophyll cells
Authors: Zhang Liyong , McEvoy Delanie , Le Yen , Ambrose Chris
Published: January 2021

Leaf spongy mesophyll cells form an interconnected network of branched cells and intercellular spaces to maximize the surface area available for light capture and photosynthetic gas exchange. To investigate the morphogenetic events leading to cell separation and branching in Arabidopsis thaliana, we used mesophyll-specific promoters to facilitate imaging of mesophyll cell shape and microtubule (MT) organization over multiple spatiotemporal scales without interference from the overlying epidermal cells. We show that cells enlarge by selective expansion of cell wall regions in contact with intercellular spaces. Cell–cell contacts remain relatively fixed in size, forming the termini of interconnecting branches. Surprisingly, classic schizogeny (de-adhesion of neighboring cells) is relatively infrequent, being related to the local topology of cell junctions during early expansion. Intercellular spaces cue the position of stable MT bundles, which in turn promote efficient dilation of intercellular spaces and cell branching. Our data provide insights into mesophyll morphogenesis and MT organization and lay the groundwork for future investigations.
Natural allelic variation in a modulator of auxin homeostasis improves grain yield and nitrogen use efficiency in rice
Authors: Zhang Siyu , Zhu Limei , Shen Chengbo , Ji Zhe , Zhang Haipeng , Zhang Tao , Li Yu , Yu Jianping , Yang Ning , He Yubing , Tian Yanan , Wu Kun , Wu Juyou , Harberd Nicholas P , Zhao Yunde , Fu Xiangdong , Wang Shaokui , Li Shan
Published: January 2021

The external application of nitrogen (N) fertilizers is an important practice for increasing crop production. However, the excessive use of fertilizers significantly increases production costs and causes environmental problems, making the improvement of crop N-use efficiency (NUE) crucial for sustainable agriculture in the future. Here we show that the rice (Oryza sativa) NUE quantitative trait locus DULL NITROGEN RESPONSE1 (qDNR1), which is involved in auxin homeostasis, reflects the differences in nitrate (NO3−) uptake, N assimilation, and yield enhancement between indica and japonica rice varieties. Rice plants carrying the DNR1indica allele exhibit reduced N-responsive transcription and protein abundance of DNR1. This, in turn, promotes auxin biosynthesis, thereby inducing AUXIN RESPONSE FACTOR-mediated activation of NO3− transporter and N-metabolism genes, resulting in improved NUE and grain yield. We also show that a loss-of-function mutation at the DNR1 locus is associated with increased N uptake and assimilation, resulting in improved rice yield under moderate levels of N fertilizer input. Therefore, modulating the DNR1-mediated auxin response represents a promising strategy for achieving environmentally sustainable improvements in rice yield.