The growth of plants, algae, and cyanobacteria relies on the catalytic activity of the oxygen-evolving PSII complex, which uses solar energy to extract electrons from water to feed into the photosynthetic electron transport chain. PSII is proving to be an excellent system to study how large multi-subunit membrane-protein complexes are assembled in the thylakoid membrane and subsequently repaired in response to photooxidative damage. Here we summarize recent developments in understanding the biogenesis of PSII, with an emphasis on recent insights obtained from biochemical and structural analysis of cyanobacterial PSII assembly/repair intermediates. We also discuss how chlorophyll synthesis is synchronized with protein synthesis and suggest a possible role for PSI in PSII assembly. Special attention is paid to unresolved and controversial issues that could be addressed in future research.
Cereal grains are an important source of food and feed. To provide comprehensive spatiotemporal information about biological processes in developing seeds of cultivated barley (Hordeum vulgare L. subsp. vulgare), we performed a transcriptomic study of the embryo, endosperm, and seed maternal tissues collected from grains 4-32 days after pollination. Weighted gene co-expression network and motif enrichment analyses identified specific groups of genes and transcription factors (TFs) potentially regulating barley seed tissue development. We defined a set of tissue-specific marker genes and families of TFs for functional studies of the pathways controlling barley grain development. Assessing selected groups of chromatin regulators revealed that epigenetic processes are highly dynamic and likely play a major role during barley endosperm development. The repressive H3K27me3 modification is globally reduced in endosperm tissues and at specific genes related to development and storage compounds. Altogether, this atlas uncovers the complexity of developmentally regulated gene expression in developing barley grains.
- MeSH
- endosperm * genetika metabolismus růst a vývoj MeSH
- epigeneze genetická MeSH
- genové regulační sítě MeSH
- histony metabolismus genetika MeSH
- ječmen (rod) * genetika růst a vývoj metabolismus MeSH
- regulace genové exprese u rostlin * MeSH
- rostlinné proteiny genetika metabolismus MeSH
- semena rostlinná * genetika růst a vývoj metabolismus MeSH
- stanovení celkové genové exprese MeSH
- transkripční faktory genetika metabolismus MeSH
- transkriptom * genetika MeSH
- vývojová regulace genové exprese MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- histony MeSH
- rostlinné proteiny MeSH
- transkripční faktory MeSH
Plants in habitats with unpredictable conditions often have diversified bet-hedging strategies that ensure fitness over a wider range of variable environmental factors. A striking example is the diaspore (seed and fruit) heteromorphism that evolved to maximize species survival in Aethionema arabicum (Brassicaceae) in which external and endogenous triggers allow the production of two distinct diaspores on the same plant. Using this dimorphic diaspore model, we identified contrasting molecular, biophysical, and ecophysiological mechanisms in the germination responses to different temperatures of the mucilaginous seeds (M+ seed morphs), the dispersed indehiscent fruits (IND fruit morphs), and the bare non-mucilaginous M- seeds obtained by pericarp (fruit coat) removal from IND fruits. Large-scale comparative transcriptome and hormone analyses of M+ seeds, IND fruits, and M- seeds provided comprehensive datasets for their distinct thermal responses. Morph-specific differences in co-expressed gene modules in seeds, as well as in seed and pericarp hormone contents, identified a role of the IND pericarp in imposing coat dormancy by generating hypoxia affecting abscisic acid (ABA) sensitivity. This involved expression of morph-specific transcription factors, hypoxia response, and cell wall remodeling genes, as well as altered ABA metabolism, transport, and signaling. Parental temperature affected ABA contents and ABA-related gene expression and altered IND pericarp biomechanical properties. Elucidating the molecular framework underlying the diaspore heteromorphism can provide insight into developmental responses to globally changing temperatures.
- MeSH
- Brassicaceae * genetika fyziologie metabolismus MeSH
- klíčení * genetika fyziologie MeSH
- kyselina abscisová metabolismus MeSH
- ovoce * genetika fyziologie růst a vývoj metabolismus MeSH
- regulace genové exprese u rostlin * MeSH
- regulátory růstu rostlin metabolismus MeSH
- semena rostlinná * genetika fyziologie růst a vývoj metabolismus MeSH
- teplota * MeSH
- transkriptom genetika MeSH
- vegetační klid genetika fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- kyselina abscisová MeSH
- regulátory růstu rostlin MeSH
Model species continue to underpin groundbreaking plant science research. At the same time, the phylogenetic resolution of the land plant tree of life continues to improve. The intersection of these 2 research paths creates a unique opportunity to further extend the usefulness of model species across larger taxonomic groups. Here we promote the utility of the Arabidopsis thaliana model species, especially the ability to connect its genetic and functional resources, to species across the entire Brassicales order. We focus on the utility of using genomics and phylogenomics to bridge the evolution and diversification of several traits across the Brassicales to the resources in Arabidopsis, thereby extending scope from a model species by establishing a "model clade." These Brassicales-wide traits are discussed in the context of both the model species Arabidopsis and the family Brassicaceae. We promote the utility of such a "model clade" and make suggestions for building global networks to support future studies in the model order Brassicales.
Polar auxin transport in the Arabidopsis (Arabidopsis thaliana) root tip maintains high auxin levels around the stem cell niche that gradually decrease in dividing cells but increase again once they transition toward differentiation. Protophloem differentiates earlier than other proximal tissues and employs a unique auxin "canalization" machinery that is thought to balance auxin efflux with retention. It consists of a proposed activator of PIN-FORMED (PIN) auxin efflux carriers, the cAMP-, cGMP- and Calcium-dependent (AGC) kinase PROTEIN KINASE ASSOCIATED WITH BRX (PAX); its inhibitor, BREVIS RADIX (BRX); and PHOSPHATIDYLINOSITOL-4-PHOSPHATE-5-KINASE (PIP5K) enzymes, which promote polar PAX and BRX localization. Because of a dynamic PAX-BRX-PIP5K interplay, the net cellular output of this machinery remains unclear. In this study, we deciphered the dosage-sensitive regulatory interactions among PAX, BRX, and PIP5K by their ectopic expression in developing xylem vessels. The data suggest that the dominant collective output of the PAX-BRX-PIP5K module is a localized reduction in PIN abundance. This requires PAX-stimulated clathrin-mediated PIN endocytosis upon site-specific phosphorylation, which distinguishes PAX from other AGC kinases. An ectopic assembly of the PAX-BRX-PIP5K module is sufficient to cause cellular auxin retention and affects root growth vigor by accelerating the trajectory of xylem vessel development. Our data thus provide direct evidence that local manipulation of auxin efflux alters the timing of cellular differentiation in the root.
- MeSH
- Arabidopsis * metabolismus genetika růst a vývoj MeSH
- biologický transport MeSH
- fosfotransferasy s alkoholovou skupinou jako akceptorem metabolismus genetika MeSH
- kořeny rostlin metabolismus růst a vývoj genetika MeSH
- kyseliny indoloctové * metabolismus MeSH
- membránové transportní proteiny metabolismus genetika MeSH
- protein-serin-threoninkinasy * MeSH
- proteiny huseníčku * metabolismus genetika MeSH
- regulace genové exprese u rostlin MeSH
- xylém metabolismus růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- AT1G66150 protein, Arabidopsis MeSH Prohlížeč
- BREVIS RADIX protein, Arabidopsis MeSH Prohlížeč
- fosfotransferasy s alkoholovou skupinou jako akceptorem MeSH
- kyseliny indoloctové * MeSH
- membránové transportní proteiny MeSH
- protein-serin-threoninkinasy * MeSH
- proteiny huseníčku * MeSH
Exocyst component of 70-kDa (EXO70) proteins are constituents of the exocyst complex implicated in vesicle tethering during exocytosis. MILDEW RESISTANCE LOCUS O (MLO) proteins are plant-specific calcium channels and some MLO isoforms enable fungal powdery mildew pathogenesis. We here detected an unexpected phenotypic overlap of Arabidopsis thaliana exo70H4 and mlo2 mlo6 mlo12 triple mutant plants regarding the biogenesis of leaf trichome secondary cell walls. Biochemical and Fourier transform infrared spectroscopic analyses corroborated deficiencies in the composition of trichome cell walls in these mutants. Transgenic lines expressing fluorophore-tagged EXO70H4 and MLO exhibited extensive colocalization of these proteins. Furthermore, mCherry-EXO70H4 mislocalized in trichomes of the mlo triple mutant and, vice versa, MLO6-GFP mislocalized in trichomes of the exo70H4 mutant. Expression of GFP-marked PMR4 callose synthase, a known cargo of EXO70H4-dependent exocytosis, revealed reduced cell wall delivery of GFP-PMR4 in trichomes of mlo triple mutant plants. In vivo protein-protein interaction assays in plant and yeast cells uncovered isoform-preferential interactions between EXO70.2 subfamily members and MLO proteins. Finally, exo70H4 and mlo6 mutants, when combined, showed synergistically enhanced resistance to powdery mildew attack. Taken together, our data point to an isoform-specific interplay of EXO70 and MLO proteins in the modulation of trichome cell wall biogenesis and powdery mildew susceptibility.
- MeSH
- Arabidopsis * metabolismus MeSH
- buněčná stěna metabolismus MeSH
- nemoci rostlin mikrobiologie MeSH
- odolnost vůči nemocem genetika MeSH
- protein - isoformy genetika metabolismus MeSH
- proteiny huseníčku * genetika metabolismus MeSH
- rostlinné proteiny metabolismus MeSH
- trichomy genetika metabolismus MeSH
- vezikulární transportní proteiny metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- EXO70H4 protein, Arabidopsis MeSH Prohlížeč
- protein - isoformy MeSH
- proteiny huseníčku * MeSH
- rostlinné proteiny MeSH
- vezikulární transportní proteiny MeSH
Plant nucleotide-binding leucine-rich repeat (NLRs) immune receptors directly or indirectly recognize pathogen-secreted effector molecules to initiate plant defense. Recognition of multiple pathogens by a single NLR is rare and usually occurs via monitoring for changes to host proteins; few characterized NLRs have been shown to recognize multiple effectors. The barley (Hordeum vulgare) NLR gene Mildew locus a (Mla) has undergone functional diversification, and the proteins encoded by different Mla alleles recognize host-adapted isolates of barley powdery mildew (Blumeria graminis f. sp. hordei [Bgh]). Here, we show that Mla3 also confers resistance to the rice blast fungus Magnaporthe oryzae in a dosage-dependent manner. Using a forward genetic screen, we discovered that the recognized effector from M. oryzae is Pathogenicity toward Weeping Lovegrass 2 (Pwl2), a host range determinant factor that prevents M. oryzae from infecting weeping lovegrass (Eragrostis curvula). Mla3 has therefore convergently evolved the capacity to recognize effectors from diverse pathogens.
- MeSH
- Ascomycota * MeSH
- Eragrostis * metabolismus MeSH
- hostitelská specificita MeSH
- ječmen (rod) * genetika MeSH
- Magnaporthe * MeSH
- nemoci rostlin mikrobiologie MeSH
- rostlinné proteiny genetika metabolismus MeSH
- rostliny metabolismus MeSH
- virulence genetika MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- rostlinné proteiny MeSH
The MADS domain transcription factor AGAMOUS (AG) regulates floral meristem termination by preventing maintenance of the histone modification lysine 27 of histone H3 (H3K27me3) along the KNUCKLES (KNU) coding sequence. At 2 d after AG binding, cell division has diluted the repressive mark H3K27me3, allowing activation of KNU transcription prior to floral meristem termination. However, how many other downstream genes are temporally regulated by this intrinsic epigenetic timer and what their functions are remain unknown. Here, we identify direct AG targets regulated through cell cycle-coupled H3K27me3 dilution in Arabidopsis thaliana. Expression of the targets KNU, AT HOOK MOTIF NUCLEAR LOCALIZED PROTEIN18 (AHL18), and PLATZ10 occurred later in plants with longer H3K27me3-marked regions. We established a mathematical model to predict timing of gene expression and manipulated temporal gene expression using the H3K27me3-marked del region from the KNU coding sequence. Increasing the number of del copies delayed and reduced KNU expression in a polycomb repressive complex 2- and cell cycle-dependent manner. Furthermore, AHL18 was specifically expressed in stamens and caused developmental defects when misexpressed. Finally, AHL18 bound to genes important for stamen growth. Our results suggest that AG controls the timing of expression of various target genes via cell cycle-coupled dilution of H3K27me3 for proper floral meristem termination and stamen development.
- MeSH
- Arabidopsis * metabolismus MeSH
- buněčné dělení MeSH
- histony genetika metabolismus MeSH
- květy fyziologie MeSH
- meristém MeSH
- protein AGAMOUS z huseníčku genetika metabolismus MeSH
- proteiny huseníčku * genetika metabolismus MeSH
- regulace genové exprese u rostlin genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- histony MeSH
- protein AGAMOUS z huseníčku MeSH
- proteiny huseníčku * MeSH
Even though Sugars Will Eventually be Exported Transporters (SWEETs) have been found in every sequenced plant genome, a comprehensive understanding of their functionality is lacking. In this study, we focused on the SWEET family of barley (Hordeum vulgare). A radiotracer assay revealed that expressing HvSWEET11b in African clawed frog (Xenopus laevis) oocytes facilitated the bidirectional transfer of not only just sucrose and glucose, but also cytokinin. Barley plants harboring a loss-of-function mutation of HvSWEET11b could not set viable grains, while the distribution of sucrose and cytokinin was altered in developing grains of plants in which the gene was knocked down. Sucrose allocation within transgenic grains was disrupted, which is consistent with the changes to the cytokinin gradient across grains, as visualized by magnetic resonance imaging and Fourier transform infrared spectroscopy microimaging. Decreasing HvSWEET11b expression in developing grains reduced overall grain size, sink strength, the number of endopolyploid endosperm cells, and the contents of starch and protein. The control exerted by HvSWEET11b over sugars and cytokinins likely predetermines their synergy, resulting in adjustments to the grain's biochemistry and transcriptome.
- MeSH
- cukry metabolismus MeSH
- cytokininy * metabolismus MeSH
- ječmen (rod) * genetika metabolismus MeSH
- rostlinné proteiny genetika metabolismus MeSH
- sacharosa metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cukry MeSH
- cytokininy * MeSH
- rostlinné proteiny MeSH
- sacharosa MeSH
DNA-protein cross-links (DPCs) are highly toxic DNA lesions consisting of proteins covalently attached to chromosomal DNA. Unrepaired DPCs physically block DNA replication and transcription. Three DPC repair pathways have been identified in Arabidopsis (Arabidopsis thaliana) to date: the endonucleolytic cleavage of DNA by the structure-specific endonuclease MUS81; proteolytic degradation of the crosslinked protein by the metalloprotease WSS1A; and cleavage of the cross-link phosphodiester bonds by the tyrosyl phosphodiesterases TDP1 and TDP2. Here we describe the evolutionary conserved STRUCTURAL MAINTENANCE OF CHROMOSOMEs SMC5/6 complex as a crucial component involved in DPC repair. We identified multiple alleles of the SMC5/6 complex core subunit gene SMC6B via a forward-directed genetic screen designed to identify the factors involved in the repair of DPCs induced by the cytidine analog zebularine. We monitored plant growth and cell death in response to DPC-inducing chemicals, which revealed that the SMC5/6 complex is essential for the repair of several types of DPCs. Genetic interaction and sensitivity assays showed that the SMC5/6 complex works in parallel to the endonucleolytic and proteolytic pathways. The repair of zebularine-induced DPCs was associated with SMC5/6-dependent SUMOylation of the damage sites. Thus, we present the SMC5/6 complex as an important factor in plant DPC repair.
- MeSH
- Arabidopsis * genetika metabolismus MeSH
- DNA metabolismus MeSH
- oprava DNA genetika MeSH
- poškození DNA MeSH
- proteiny buněčného cyklu genetika metabolismus MeSH
- proteiny metabolismus MeSH
- sumoylace MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- DNA MeSH
- proteiny buněčného cyklu MeSH
- proteiny MeSH
