Low molecular weight secreted peptides have recently been shown to affect multiple aspects of plant growth, development, and defense responses. Here, we performed stepwise BLAST filtering to identify ...unannotated peptides from the Arabidopsis thaliana protein database and uncovered a novel secreted peptide family, secreted transmembrane peptides (STMPs). These low molecular weight peptides, which consist of an N‐terminal signal peptide and a transmembrane domain, were primarily localized to extracellular compartments but were also detected in the endomembrane system of the secretory pathway, including the endoplasmic reticulum and Golgi. Comprehensive bioinformatics analysis identified 10 STMP family members that are specific to the Brassicaceae family. Brassicaceae plants showed dramatically inhibited root growth upon exposure to chemically synthesized STMP1 and STMP2. Arabidopsis overexpressing STMP1, 2, 4, 6, or 10 exhibited severely arrested growth, suggesting that STMPs are involved in regulating plant growth and development. In addition, in vitro bioassays demonstrated that STMP1, STMP2, and STMP10 have antibacterial effects against Pseudomonas syringae pv. tomato DC3000, Ralstonia solanacearum, Bacillus subtilis, and Agrobacterium tumefaciens, demonstrating that STMPs are antimicrobial peptides. These findings suggest that STMP family members play important roles in various developmental events and pathogen defense responses in Brassicaceae plants.
It is well known that communication among animal organs requires “signal molecules”, so it is necessary to identify such of “signal molecules” in plants. In this study, a class of “small molecule proteins” which can both regulate plant growth and help plants resist pathogens were found.
The present study is focused on the cytogenetic and morphological criteria for distinguishing new taxa belonging to Fibigia sect. Purpureae. This section in Iran is revised, and three new species (F. ...kermanshahensis Ranjbar & Karami, F. khoshyelaqensis Ranjbar & Rostami, and F. tabriziana Ranjbar & Karami) are described and illustrated from Kermanshah, Gorgan and Azarbaijan Sharqi Provinces. These are closely related to F. suffruticosa (Vent.) Sweet. but differs from it in morphological characters such as plant indumentums, fruits size and shape, lateral sepals saccate at base and stigma size and shape. The meiotic chromosome number and behavior were studied in F. kermanshahensis and F. suffruticosa. F. kermanshahensis is a diploid plant and possesses the chromosome number 2n = 2x = 14, inconsistent with the base number of F. suffruticosa witch shows 2n = 2x = 16. The general meiotic behavior in both species was regular, with bivalent pairing and normal chromosome segregation at meiosis. However, some meiotic abnormalities were observed including varied degrees of sticky chromosomes with laggards, a precocious division of centromeres in metaphase I and metaphase II, bridges in anaphase II, laggard chromosomes, micronucleus, asynchronous nucleus and cytomixis. Finally, a key to all four species of this section is presented.
Coevolutionary interactions are thought to have spurred the evolution of key innovations and driven the diversification of much of life on Earth. However, the genetic and evolutionary basis of the ...innovations that facilitate such interactions remains poorly understood. We examined the coevolutionary interactions between plants (Brassicales) and butterflies (Pieridae), and uncovered evidence for an escalating evolutionary arms-race. Although gradual changes in trait complexity appear to have been facilitated by allelic turnover, key innovations are associated with gene and genome duplications. Furthermore, we show that the origins of both chemical defenses and of molecular counter adaptations were associated with shifts in diversification rates during the arms-race. These findings provide an important connection between the origins of biodiversity, coevolution, and the role of gene and genome duplications as a substrate for novel traits.
The effects of short-term salt stress on gas exchange and the regulation of photosynthetic electron transport were examined in Arabidopsis (Arabidopsis thaliana) and its salt-tolerant close relative ...Thellungiella (Thellungiella halophila). Plants cultivated on soil were challenged for 2 weeks with NaCl. Arabidopsis showed a much higher sensitivity to salt than Thellungiella; while Arabidopsis plants were unable to survive exposure to greater than 150 mM salt, Thellugiella could tolerate concentrations as high as 500 mM with only minimal effects on gas exchange. Exposure of Arabidopsis to sublethal salt concentrations resulted in stomatal closure and inhibition of CO₂ fixation. This lead to an inhibition of electron transport though photosystem II (PSII), an increase in cyclic electron flow involving only PSI, and increased nonphotochemical quenching of chlorophyll fluorescence. In contrast, in Thellungiella, although gas exchange was marginally inhibited by high salt and PSI was unaffected, there was a large increase in electron flow involving PSII. This additional electron transport activity is oxygen dependent and sensitive to the alternative oxidase inhibitor n-propyl gallate. PSII electron transport in Thellungiella showed a reduced sensitivity to 2'-iodo-6-isopropyl-3-methyl-2',4,4'-trinitrodiphenylether, an inhibitor of the cytochrome b₆f complex. At the same time, we observed a substantial up-regulation of a protein reacting with antibodies raised against the plastid terminal oxidase. No such up-regulation was seen in Arabidopsis. We conclude that in salt-stressed Thellungiella, plastid terminal oxidase acts as an alternative electron sink, accounting for up to 30% of total PSII electron flow.
Chlorophyll fluorescence kinetic analysis has become an important tool in basic and applied research on plant physiology and agronomy. While early systems recorded the integrated kinetics of a ...selected spot or plant, later systems enabled imaging of at least the slower parts of the kinetics (20-ms time resolution). For faster events, such as the rise from the basic dark-adapted fluorescence yield to the maximum (OJIP transient), or the fluorescence yield decrease during reoxidation of plastoquinone A after a saturating flash, integrative systems are used because of limiting speed of the available imaging systems. In our new macroscopic and microscopic systems, the OJIP or plastonique A reoxidation fluorescence transients are directly imaged using an ultrafast camera. The advantage of such systems compared to nonimaging measurements is the analysis of heterogeneity of measured parameters, for example between the photosynthetic tissue near the veins and the tissue further away from the veins. Further, in contrast to the pump-and-probe measurement, direct imaging allows for measuring the transition of the plant from the dark-acclimated to a light-acclimated state via a quenching analysis protocol in which every supersaturating flash is coupled to a measurement of the fast fluorescence rise. We show that pump-and-probe measurement of OJIP is prone to artifacts, which are eliminated with the direct measurement. The examples of applications shown here, zinc deficiency and cadmium toxicity, demonstrate that this novel imaging platform can be used for detection and analysis of a range of alterations of the electron flow around PSII.
NAC proteins constitute one of the largest families of plant-specific transcription factors, and a number of these proteins participate in the regulation of plant development and responses to abiotic ...stress. T. HALOPHILA STRESS RELATED NAC1 (TsNAC1), cloned from the halophyte Thellungiella halophila, is a NAC transcription factor gene, and its overexpression can improve abiotic stress resistance, especially in salt stress tolerance, in both T. halophila and Arabidopsis (Arabidopsis thaliana) and retard the growth of these plants. In this study, the transcriptional activation activity of TsNAC1 and RD26 from Arabidopsis was compared with the target genes' promoter regions of TsNAC1 from T. halophila, and the results showed that the transcriptional activation activity of TsNAC1 was higher in tobacco (Nicotiana tabacum) and yeast. The target sequence of the promoter from the target genes also was identified, and TsNAC1 was shown to target the positive regulators of ion transportation, such as T. HALOPHILA H⁺-PPASE1, and the transcription factors MYB HYPOCOTYL ELONGATION-RELATED and HOMEOBOX12. In addition, TsNAC1 negatively regulates the expansion of cells, inhibits LIGHT-DEPENDENT SHORT HYPOCOTYLS1 and UDP-XYLOSYLTRANSFERASE2, and directly controls the expression of MULTICOPY SUPPRESSOR OF IRA14. Based on these results, we propose that TsNAC1 functions as an important upstream regulator of plant abiotic stress responses and vegetative growth.
Understanding how plants cope with changing habitats is a timely and important topic in plant research. Phenotypic plasticity describes the capability of a genotype to produce different phenotypes ...when exposed to different environmental conditions. In contrast, the constant production of a set of distinct phenotypes by one genotype mediates bet hedging, a strategy that reduces the temporal variance in fitness at the expense of a lowered arithmetic mean fitness. Both phenomena are thought to represent important adaptation strategies to unstable environments. However, little is known about the underlying mechanisms of these phenomena, partly due to the lack of suitable model systems. We used phylogenetic and comparative analyses of fruit and seed anatomy, biomechanics, physiology, and environmental responses to study fruit and seed heteromorphism, a typical morphological basis of a bet-hedging strategy of plants, in the annual Brassicaceae species Aethionema arabicum. Our results indicate that heteromorphism evolved twice within the Aethionemeae, including once for themonophyletic annual Aethionema clade. The dimorphism of Ae. arabicum is associated with several anatomic, biomechanical, gene expression, and physiological differences between the fruit and seed morphs. However, fruit ratios and numbers change in response to different environmental conditions. Therefore, the life-history strategy of Ae. arabicum appears to be a blend of bet hedging and plasticity. Together with the available genomic resources, our results pave the way to use this species in future studies intended to unravel the molecular control of heteromorphism and plasticity.
Abstract
The Brassicaceae Database (BRAD version 3.0, BRAD V3.0; http://brassicadb.cn) has evolved from the former Brassica Database (BRAD V2.0), and represents an important community portal hosting ...genome information for multiple Brassica and related Brassicaceae plant species. Since the last update in 2015, the complex genomes of numerous Brassicaceae species have been decoded, accompanied by many omics datasets. To provide an up-to-date service, we report here a major upgrade of the portal. The Model-View-ViewModel (MVVM) framework of BRAD has been re-engineered to enable easy and sustainable maintenance of the database. The collection of genomes has been increased to 26 species, along with optimization of the user interface. Features of the previous version have been retained, with additional new tools for exploring syntenic genes, gene expression and variation data. In the ‘Syntenic Gene @ Subgenome’ module, we added features to view the sequence alignment and phylogenetic relationships of syntenic genes. New modules include ‘MicroSynteny’ for viewing synteny of selected fragment pairs, and ‘Polymorph’ for retrieval of variation data. The updated BRAD provides a substantial expansion of genomic data and a comprehensive improvement of the service available to the Brassicaceae research community.
We critically review documented glucosinolate structures, methods for qualitative glucosinolate analysis, glucosinolate evolution, and recent advances in glucosinolate biochemistry. Rather than being ...neutral markers of evolutionary origin, glucosinolates are bioactive specialized metabolites, and their evolution can be traced using phylogenetic trees. Display omitted
► We provide a critical review of reported natural glucosinolate structures. ► A considerable number of suggested structures are insufficiently documented. ► By 2011, around 132 natural glucosinolates were scientifically documented. ► Glucosinolates are specialized metabolites subject to frequent evolution. ► Side chain specific in planta metabolic reactions may influence glucosinolate evolution.
By 2000, around 106 natural glucosinolates (GSLs) were probably documented. In the past decade, 26 additional natural GSL structures have been elucidated and documented. Hence, the total number of documented GSLs from nature by 2011 can be estimated to around 132. A considerable number of additional suggested structures are concluded not to be sufficiently documented. In many cases, NMR spectroscopy would have provided the missing structural information. Of the GSLs documented in the past decade, several are of previously unexpected structures and occur at considerable levels. Most originate from just four species: Barbarea vulgaris, Arabidopsis thaliana, Eruca sativa and Isatis tinctoria. Acyl derivatives of known GSLs comprised 15 of the 26 newly documented structures, while the remaining exhibited new substitution patterns or chain length, or contained a mercapto group or related thio-functionality.
GSL identification methods are reviewed, and the importance of using authentic references and structure-sensitive detection methods such as MS and NMR is stressed, especially when species with relatively unknown chemistry are analyzed. An example of qualitative GSL analysis is presented with experimental details (group separation and HPLC of both intact and desulfated GSLs, detection and structure determination by UV, MS, NMR and susceptibility to myrosinase) with emphasis on the use of NMR for structure elucidation of even minor GSLs and GSL hydrolysis products. The example includes identification of a novel GSL, (R)-2-hydroxy-2-(3-hydroxyphenyl)ethylglucosinolate.
Recent investigations of GSL evolution, based on investigations of species with well established phylogeny, are reviewed. From the relatively few such investigations, it is already clear that GSL profiles are regularly subject to evolution. This result is compatible with natural selection for specific GSL side chains. The probable existence of structure-specific GSL catabolism in intact plants suggests that biochemical evolution of GSLs has more complex implications than the mere liberation of a different hydrolysis product upon tissue disruption.
The family Brassicaceae encompasses diverse species, many of which have high scientific and economic importance. Early diversifications and phylogenetic relationships between major lineages or clades ...remain unclear. Here we re-investigate Brassicaceae phylogeny with complete plastomes from 51 species representing all four lineages or 5 of 6 major clades (A, B, C, E and F) as identified in earlier studies.
Bayesian and maximum likelihood phylogenetic analyses using a partitioned supermatrix of 77 protein coding genes resulted in nearly identical tree topologies exemplified by highly supported relationships between clades. All four lineages were well identified and interrelationships between them were resolved. The previously defined Clade C was found to be paraphyletic (the genus Megadenia formed a separate lineage), while the remaining clades were monophyletic. Clade E (lineage III) was sister to clades B + C rather than to all core Brassicaceae (clades A + B + C or lineages I + II), as suggested by a previous transcriptome study. Molecular dating based on plastome phylogeny supported the origin of major lineages or clades between late Oligocene and early Miocene, and the following radiative diversification across the family took place within a short timescale. In addition, gene losses in the plastomes occurred multiple times during the evolutionary diversification of the family.
Plastome phylogeny illustrates the early diversification of cruciferous species. This phylogeny will facilitate our further understanding of evolution and adaptation of numerous species in the model family Brassicaceae.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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