Secondary dormancy is an adaptive trait that increases reproductive success by aligning seed germination with permissive conditions for seedling establishment. Aethionema arabicum is an annual plant and member of the Brassicaceae that grows in environments characterized by hot and dry summers. Aethionema arabicum seeds may germinate in early spring when seedling establishment is permissible. We demonstrate that long-day light regimes induce secondary dormancy in the seeds of Aethionema arabicum (CYP accession), repressing germination in summer when seedling establishment is riskier. Characterization of mutants screened for defective secondary dormancy demonstrated that RGL2 mediates repression of genes involved in gibberellin (GA) signaling. Exposure to high temperature alleviates secondary dormancy, restoring germination potential. These data are consistent with the hypothesis that long-day-induced secondary dormancy and its alleviation by high temperatures may be part of an adaptive response limiting germination to conditions permissive for seedling establishment in spring and autumn.
- Klíčová slova
- Aethionema arabicum, Mediterranean climate, abscisic acid, adaptation, day-length, dormancy cycling, germination, gibberellin, light, seed dormancy,
- MeSH
- Brassicaceae * fyziologie MeSH
- fotoperioda MeSH
- fyziologická adaptace MeSH
- gibereliny metabolismus MeSH
- klíčení * MeSH
- regulace genové exprese u rostlin MeSH
- roční období MeSH
- rostlinné proteiny genetika metabolismus MeSH
- semena rostlinná * růst a vývoj fyziologie MeSH
- semenáček růst a vývoj fyziologie MeSH
- vegetační klid * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- gibereliny MeSH
- rostlinné proteiny 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
Deserts exert strong selection pressures on plants, but the underlying genomic drivers of ecological adaptation and subsequent speciation remain largely unknown. Here, we generated de novo genome assemblies and conducted population genomic analyses of the psammophytic genus Pugionium (Brassicaceae). Our results indicated that this bispecific genus had undergone an allopolyploid event, and the two parental genomes were derived from two ancestral lineages with different chromosome numbers and structures. The postpolyploid expansion of gene families related to abiotic stress responses and lignin biosynthesis facilitated environmental adaptations of the genus to desert habitats. Population genomic analyses of both species further revealed their recent divergence with continuous gene flow, and the most divergent regions were found to be centered on three highly structurally reshuffled chromosomes. Genes under selection in these regions, which were mainly located in one of the two subgenomes, contributed greatly to the interspecific divergence in microhabitat adaptation.
- Klíčová slova
- chromosomal structural variation, desert plants, microhabitat divergence, polyploidization,
- MeSH
- Brassicaceae klasifikace genetika fyziologie MeSH
- ekosystém * MeSH
- fylogeneze MeSH
- fyziologická adaptace genetika MeSH
- genom rostlinný * MeSH
- polyploidie MeSH
- vznik druhů (genetika) * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The developmental transition from a fertilized ovule to a dispersed diaspore (seed or fruit) involves complex differentiation processes of the ovule's integuments leading to the diversity in mature seed coat structures in angiosperms. In this study, comparative imaging and transcriptome analysis were combined to investigate the morph-specific developmental differences during outer seed coat differentiation and mucilage production in Aethionema arabicum, the Brassicaceae model for diaspore dimorphism. One of the intriguing adaptations of this species is the production and dispersal of morphologically distinct, mucilaginous and non-mucilaginous diaspores from the same plant (dimorphism). The dehiscent fruit morph programme producing multiple mucilaginous seed diaspores was used as the default trait combination, similar to Arabidopsis thaliana, and was compared with the indehiscent fruit morph programme leading to non-mucilaginous diaspores. Synchrotron-based radiation X-ray tomographic microscopy revealed a co-ordinated framework of morph-specific early changes in internal anatomy of developing A. arabicum gynoecia including seed abortion in the indehiscent programme and mucilage production by the mucilaginous seed coat. The associated comparative analysis of the gene expression patterns revealed that the unique seed coat dimorphism of Ae. arabicum provides an excellent model system for comparative study of the control of epidermal cell differentiation and mucilage biosynthesis by the mucilage transcription factor cascade and their downstream cell wall and mucilage remodelling genes. Elucidating the underlying molecular framework of the dimorphic diaspore syndrome is key to understanding differential regulation of bet-hedging survival strategies in challenging environments, timely in the face of global climatic change.
- Klíčová slova
- Aethionema arabicum, bet-hedging, developmental anatomy, diaspore dimorphism, fruit development, phenotypic plasticity, reproductive development, seed coat mucilage, synchrotron radiation X-ray tomographic microscopy, transcription factors,
- MeSH
- Brassicaceae cytologie růst a vývoj fyziologie MeSH
- buněčná diferenciace MeSH
- kyselina abscisová metabolismus MeSH
- leucinové zipy MeSH
- ovoce genetika růst a vývoj MeSH
- regulace genové exprese u rostlin * MeSH
- rostlinné buňky MeSH
- rostlinné proteiny genetika MeSH
- sekvenční analýza RNA MeSH
- semena rostlinná genetika růst a vývoj metabolismus MeSH
- transkripční faktory genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- kyselina abscisová MeSH
- rostlinné proteiny MeSH
- transkripční faktory MeSH
Aethionema arabicum is an important model plant for Brassicaceae trait evolution, particularly of seed (development, regulation, germination, dormancy) and fruit (development, dehiscence mechanisms) characters. Its genome assembly was recently improved but the gene annotation was not updated. Here, we improved the Ae. arabicum gene annotation using 294 RNA-seq libraries and 136 307 full-length PacBio Iso-seq transcripts, increasing BUSCO completeness by 11.6% and featuring 5606 additional genes. Analysis of orthologs showed a lower number of genes in Ae. arabicum than in other Brassicaceae, which could be partially explained by loss of homeologs derived from the At-α polyploidization event and by a lower occurrence of tandem duplications after divergence of Aethionema from the other Brassicaceae. Benchmarking of MADS-box genes identified orthologs of FUL and AGL79 not found in previous versions. Analysis of full-length transcripts related to ABA-mediated seed dormancy discovered a conserved isoform of PIF6-β and antisense transcripts in ABI3, ABI4 and DOG1, among other cases found of different alternative splicing between Turkey and Cyprus ecotypes. The presented data allow alternative splicing mining and proposition of numerous hypotheses to research evolution and functional genomics. Annotation data and sequences are available at the Ae. arabicum DB (https://plantcode.online.uni-marburg.de/aetar_db).
- Klíčová slova
- Aethionema arabicum, Brassicaceae evolution, Iso-seq, alternative splicing, genome annotation, seed germination, transcription factors,
- MeSH
- Brassicaceae genetika metabolismus fyziologie MeSH
- genom rostlinný genetika MeSH
- klíčení genetika fyziologie MeSH
- regulace genové exprese u rostlin genetika fyziologie MeSH
- semena rostlinná genetika metabolismus fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Drought poses a serious threat to oilseed crops by lowering yield and crop failures under prolonged spells. A multi-year field investigation was conducted to enhance the drought tolerance in four genotypes of Camelina and canola by selenium (Se) application. The principal aim of the research was to optimize the crop yield by eliciting the physio-biochemical attributes by alleviating the adverse effects of drought stress. Both crops were cultivated under control (normal irrigation) and drought stress (skipping irrigation at stages i.e., vegetative and reproductive) conditions. Four different treatments of Se viz., seed priming with Se (75 μM), foliar application of Se (7.06 μM), foliar application of Se + Seed priming with Se (7.06 μM and 75 μM, respectively) and control (without Se), were implemented at the vegetative and reproductive stages of both crops. Sodium selenite (Na2SeO3), an inorganic compound was used as Se sources for both seed priming and foliar application. Data regarding physiochemical, antioxidants, and yield components were recorded as response variables at crop maturity. Results indicated that WP, OP, TP, proline, TSS, TFAA, TPr, TS, total chlorophyll contents, osmoprotectant (GB, anthocyanin, TPC, and flavonoids), antioxidants (APX, SOD, POD, and CAT), and yield components (number of branches per plant, thousand seed weight, seed, and biological yields were significantly improved by foliar Se + priming Se in both crops under drought stress. Moreover, this treatment was also helpful in boosting yield attributes under irrigated (non-stress) conditions. Camelina genotypes responded better to Se application as seed priming and foliar spray than canola for both years. It has concluded that Se application (either foliar or priming) can potentially alleviate adverse effects of drought stress in camelina and canola by eliciting various physio-biochemicals attributes under drought stress. Furthermore, Se application was also helpful for crop health under irrigated condition.
- Klíčová slova
- antioxidants, camelina, canola, drought, osmoprotectant, selenium, yield,
- MeSH
- antioxidancia analýza MeSH
- Brassica napus účinky léků růst a vývoj fyziologie MeSH
- Brassicaceae účinky léků růst a vývoj fyziologie MeSH
- období sucha * MeSH
- olej z řepky izolace a purifikace MeSH
- oleje rostlin izolace a purifikace MeSH
- osmoregulace MeSH
- rostlinné proteiny analýza MeSH
- selen aplikace a dávkování MeSH
- zemědělské plodiny účinky léků růst a vývoj fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Pákistán MeSH
- Názvy látek
- antioxidancia MeSH
- olej z řepky MeSH
- oleje rostlin MeSH
- rostlinné proteiny MeSH
- selen MeSH
Plasticity in plant dispersal traits can maximise the ability of a plant species to survive in stressful environments during colonization. Aethionema arabicum (Brassicaceae) is a dimorphic annual species that is hypothesized to survive stressful conditions during colonization due to adaptive plasticity in life-phase (vegetative vs sexual) and fruit morph (dehiscent [DEH] vs indehiscent fruits [IND]). We tested for adaptive plasticity in life-phase and fruit morphs along laboratory environmental stress gradients found in the natural habitats of Ae. arabicum. We considered optimal environmental conditions (750-2000 m above sea level) to be those that resulted in the following fitness parameters: higher biomass and a higher total number of fruits compared to stressful habitats. We found evidence of plasticity in life-phase and fruit-morph along a stressful environmental gradient. High hydrothermal stress proportionally increased the number of dehiscent morphs and non-dormant seeds germinating in autumn. This offsets natural phenology towards dry and cold winter (less hydrothermal stress), yielding fewer fruits that dehisce in the next generation. We conclude that the plastic responses of Ae. arabicum to natural stress gradients constitute a strategy of long-term adaptive benefits and favouring potential pathways of colonisation of the optimal habitat.
The timing of seed germination is crucial for seed plants and is coordinated by internal and external cues, reflecting adaptations to different habitats. Physiological and molecular studies with lettuce and Arabidopsis thaliana have documented a strict requirement for light to initiate germination and identified many receptors, signaling cascades, and hormonal control elements. In contrast, seed germination in several other plants is inhibited by light, but the molecular basis of this alternative response is unknown. We describe Aethionema arabicum (Brassicaceae) as a suitable model plant to investigate the mechanism of germination inhibition by light, as this species has accessions with natural variation between light-sensitive and light-neutral responses. Inhibition of germination occurs in red, blue, or far-red light and increases with light intensity and duration. Gibberellins and abscisic acid are involved in the control of germination, as in Arabidopsis, but transcriptome comparisons of light- and dark-exposed A. arabicum seeds revealed that, upon light exposure, the expression of genes for key regulators undergo converse changes, resulting in antipodal hormone regulation. These findings illustrate that similar modular components of a pathway in light-inhibited, light-neutral, and light-requiring germination among the Brassicaceae have been assembled in the course of evolution to produce divergent pathways, likely as adaptive traits.
- Klíčová slova
- Aethionema arabicum, light inhibition, model plant, natural variation, seed germination, transcriptional regulation,
- MeSH
- Brassicaceae fyziologie účinky záření MeSH
- exprese genu účinky záření MeSH
- gibereliny metabolismus MeSH
- klíčení účinky záření MeSH
- kyselina abscisová metabolismus MeSH
- rostlinné geny * MeSH
- sluneční záření * MeSH
- transkriptom účinky léků MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- gibereliny MeSH
- kyselina abscisová MeSH
Heteromorphic diaspores (fruits and seeds) are an adaptive bet-hedging strategy to cope with spatiotemporally variable environments, particularly fluctuations in favourable temperatures and unpredictable precipitation regimes in arid climates. We conducted comparative analyses of the biophysical and ecophysiological properties of the two distinct diaspores (mucilaginous seed (M+ ) vs indehiscent (IND) fruit) in the dimorphic annual Aethionema arabicum (Brassicaceae), linking fruit biomechanics, dispersal aerodynamics, pericarp-imposed dormancy, diaspore abscisic acid (ABA) concentration, and phenotypic plasticity of dimorphic diaspore production to its natural habitat and climate. Two very contrasting dispersal mechanisms of the A. arabicum dimorphic diaspores were revealed. Dehiscence of large fruits leads to the release of M+ seed diaspores, which adhere to substrata via seed coat mucilage, thereby preventing dispersal (antitelechory). IND fruit diaspores (containing nonmucilaginous seeds) disperse by wind or water currents, promoting dispersal (telechory) over a longer range. The pericarp properties confer enhanced dispersal ability and degree of dormancy on the IND fruit morph to support telechory, while the M+ seed morph supports antitelechory. Combined with the phenotypic plasticity to produce more IND fruit diaspores in colder temperatures, this constitutes a bet-hedging survival strategy to magnify the prevalence in response to selection pressures acting over hilly terrain.
- Klíčová slova
- Aethionema arabicum, abscisic acid (ABA), bet-hedging, dimorphic diaspores, dispersal by wind and water, environmental adaptations, fruit biomechanics, pericarp-imposed properties,
- MeSH
- biofyzikální jevy * MeSH
- biomechanika MeSH
- Brassicaceae fyziologie MeSH
- ekosystém MeSH
- fyziologická adaptace * MeSH
- klíčení fyziologie MeSH
- ovoce fyziologie MeSH
- půda MeSH
- semena rostlinná fyziologie MeSH
- šíření semen fyziologie MeSH
- vítr MeSH
- voda MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- půda MeSH
- voda MeSH
Salt stress responses in salt-sensitive Arabidopsis thaliana (2-150mM NaCl) and the closely related salt-tolerant Thellungiella salsuginea (Eutrema halophila, 150-350mM NaCl) were compared to identify hormonal and transcriptomic changes associated with enhanced stress tolerance. Phytohormone levels, expression of selected genes, membrane stability, and Na+ and K+ concentrations were measured in shoot apices, leaves, and roots. Thellungiella exhibited higher salt stress tolerance associated with elevated basal levels of abscisic acid and jasmonic acid, and lower levels of active cytokinins (excluding cis-zeatin) in shoot apices. Analysis of the dynamics of the early salt stress response (15min to 24h) revealed that the halophyte response was faster and stronger. Very mild stress, in our hydropony arrangement 2-25mM NaCl, affected the transcription of genes involved in cytokinin metabolism (AtIPTs, AtCKXs). Mild stress induced in Arabidopsis (50mM) stress responses only in shoot apices, while in Thellungiella (150mM) across the whole plant. Arabidopsis exhibited in hydropony evidence of severe stress above 75mM NaCl and died in 150mM, whereas the halophyte only became severely stressed above 225mM. The responses of individual phytohormones (cytokinins, auxin, abscisic acid, jasmonic acid, salicylic acid and their metabolites) to salinity are discussed.
- Klíčová slova
- Abscisic acid, Auxin, Cytokinin, Halophyte, Phytohormone, Salt stress,
- MeSH
- Arabidopsis genetika fyziologie MeSH
- Brassicaceae genetika fyziologie MeSH
- draslík analýza metabolismus MeSH
- fyziologický stres MeSH
- halotolerantní rostliny MeSH
- kořeny rostlin genetika fyziologie MeSH
- listy rostlin genetika fyziologie MeSH
- regulátory růstu rostlin metabolismus MeSH
- salinita MeSH
- sodík analýza metabolismus MeSH
- tolerance k soli MeSH
- výhonky rostlin fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- draslík MeSH
- regulátory růstu rostlin MeSH
- sodík MeSH
