Formation of the apical hook in etiolated dicot seedlings results from differential growth in the hypocotyl apex and is tightly controlled by environmental cues and hormones, among which auxin and gibberellins (GAs) play an important role. Cell expansion is tightly regulated by the cell wall, but whether and how feedback from this structure contributes to hook development are still unclear. Here, we show that etiolated seedlings of the Arabidopsis (Arabidopsis thaliana) quasimodo2-1 (qua2) mutant, defective in pectin biosynthesis, display severe defects in apical hook formation and maintenance, accompanied by loss of asymmetric auxin maxima and differential cell expansion.
View Article and Find Full Text PDFBackground: Semi-dwarfing alleles are used widely in cereals to confer improved lodging resistance and assimilate partitioning. The most widely deployed semi-dwarfing alleles in rice and barley encode the gibberellin (GA)-biosynthetic enzyme GA 20-OXIDASE2 (GA20OX2). The hexaploid wheat genome carries three homoeologous copies of GA20OX2, and because of functional redundancy, loss-of-function alleles of a single homoeologue would not be selected in wheat breeding programmes.
View Article and Find Full Text PDFStrigolactones are a class of phytohormones with various functions in plant development, stress responses, and in the interaction with (micro)organisms in the rhizosphere. While their effects on vegetative development are well studied, little is known about their role in reproduction. We investigated the effects of genetic and chemical modification of strigolactone levels on the timing and intensity of flowering in tomato ( L.
View Article and Find Full Text PDFPlants 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.
View Article and Find Full Text PDFB-Box-containing zinc finger transcription factors (BBX) are involved in light-mediated growth, affecting processes such as hypocotyl elongation in Arabidopsis thaliana. However, the molecular and hormonal framework that regulates plant growth through BBX proteins is incomplete. Here, we demonstrate that BBX21 inhibits the hypocotyl elongation through the brassinosteroid (BR) pathway.
View Article and Find Full Text PDFStudies of vitality/mortality of cortex cells, as well as of the concentrations of ethylene (ETH), gibberellins (GAs), indolic compounds/auxins (ICs/AUXs) and cytokinins (CKs), were undertaken to explain the hormonal background of kinetin (Kin)-regulated cell death (RCD), which is induced in the cortex of the apical parts of roots of faba bean (Vicia faba ssp. minor) seedlings. Quantification was carried out with fluorescence microscopy, ETH sensors, spectrophotometry and ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC‒MS/MS).
View Article and Find Full Text PDFWe showed that wild pea seeds contained a more diverse combination of bioactive GAs and had higher ABA content than domesticated peas. Although the role of abscisic acid (ABA) and gibberellins (GAs) interplay has been extensively studied in Arabidopsis and cereals models, comparatively little is known about the effect of domestication on the level of phytohormones in legume seeds. In legumes, as in other crops, seed dormancy has been largely or entirely removed during domestication.
View Article and Find Full Text PDFExogenously applied brassinosteroids (BRs) improve plant response to drought. However, many important aspects of this process, such as the potential differences caused by different developmental stages of analyzed organs at the beginning of drought, or by BR application before or during drought, remain still unexplored. The same applies for the response of different endogenous BRs belonging to the C, C-and C- structural groups to drought and/or exogenous BRs.
View Article and Find Full Text PDFDormancy and heteromorphism are innate seed properties that control germination timing through adaptation to the prevailing environment. The degree of variation in dormancy depth within a seed population differs considerably depending on the genotype and maternal environment. Dormancy is therefore a key trait of annual weeds to time seedling emergence across seasons.
View Article and Find Full Text PDFIncreasing crop productivity under optimal conditions and mitigating yield losses under stressful conditions is a major challenge in contemporary agriculture. We have recently identified an effective anti-senescence compound (MTU, [1-(2-methoxyethyl)-3-(1,2,3-thiadiazol-5yl)urea]) in studies. Here, we show that MTU delayed both age- and stress-induced senescence of wheat plants ( L.
View Article and Find Full Text PDFThe view on the role of light during seed germination stems mainly from studies with Arabidopsis (Arabidopsis thaliana), where light is required to initiate this process. In contrast, white light is a strong inhibitor of germination in other plants, exemplified by accessions of Aethionema arabicum, another member of Brassicaceae. Their seeds respond to light with gene expression changes of key regulators converse to that of Arabidopsis, resulting in opposite hormone regulation and prevention of germination.
View Article and Find Full Text PDFPerennial para- and endo-dormancy are seasonally separate phenomena. Whereas para-dormancy is the suppression of axillary buds (AXBs) by a growing shoot, endo-dormancy is the short-day elicited arrest of terminal and AXBs. In hybrid aspen (Populus tremula x P.
View Article and Find Full Text PDFPhloridzin is the most abundant polyphenolic compound in apple (Malus × domestica Borkh.), which results from the action of a key phloretin-specific UDP-2'-O-glucosyltransferase (MdPGT1). Here, we simultaneously assessed the effects of targeting MdPGT1 by conventional transgenesis and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-mediated genome editing.
View Article and Find Full Text PDFFront Plant Sci
September 2022
Dinoflagellate inhabitants of the reef-building corals exchange nutrients and signals with host cells, which often benefit the growth of both partners. Phytohormones serve as central hubs for signal integration between symbiotic microbes and their hosts, allowing appropriate modulation of plant growth and defense in response to various stresses. However, the presence and function of phytohormones in photosynthetic dinoflagellates and their function in the holobionts remain elusive.
View Article and Find Full Text PDFThe Oryza sativa (rice) carotenoid cleavage dioxygenase OsZAS was described to produce zaxinone, a plant growth-promoting apocarotenoid. A zas mutant line showed reduced arbuscular mycorrhizal (AM) colonization, but the mechanisms underlying this behavior are unknown. Here, we investigated how OsZAS and exogenous zaxinone treatment regulate mycorrhization.
View Article and Find Full Text PDFBackground: Bread wheat (Triticum aestivum) is a major source of nutrition globally, but yields can be seriously compromised by water limitation. Redistribution of growth between shoots and roots is a common response to drought, promoting plant survival, but reducing yield. Gibberellins (GAs) are necessary for shoot and root elongation, but roots maintain growth at lower GA concentrations compared with shoots, making GA a suitable hormone for mediating this growth redistribution.
View Article and Find Full Text PDFMolecular responses of plants to natural phytotoxins comprise more general and compound-specific mechanisms. How phytotoxic chalcones and other flavonoids inhibit seedling growth was widely studied, but how they interfere with seed germination is largely unknown. The dihydrochalcone and putative allelochemical myrigalone A (MyA) inhibits seed germination and seedling growth.
View Article and Find Full Text PDFThe dynamic behaviour of seeds in soil seed banks depends on their ability to act as sophisticated environmental sensors to adjust their sensitivity thresholds for germination by dormancy mechanisms. Here we show that prolonged incubation of sugar beet fruits at low temperature (chilling at 5°C, generally known to release seed dormancy of many species) can induce secondary nondeep physiological dormancy of an apparently nondormant crop species. The physiological and biophysical mechanisms underpinning this cold-induced secondary dormancy include the chilling-induced accumulation of abscisic acid in the seeds, a reduction in the embryo growth potential and a block in weakening of the endosperm covering the embryonic root.
View Article and Find Full Text PDFThe gibberellins (GAs) are phytohormones that play fundamental roles in almost every aspect of plant growth and development. Although GA biosynthetic and signaling pathways are well understood, the mechanisms that control GA homeostasis remain largely unclear in plants. Here, we demonstrate that the homeobox transcription factor (TF) HB40 of the HD-Zip family regulates GA content at two additive control levels in Arabidopsis thaliana.
View Article and Find Full Text PDFPlants reduce transpiration to avoid dehydration during drought episodes by stomatal closure and inhibition of canopy growth. Previous studies have suggested that low gibberellin (GA) activity promotes these 'drought avoidance' responses. Using genome editing, molecular, physiological and hormone analyses, we examined if drought regulates GA metabolism in tomato (Solanum lycopersicum) guard cells and leaves, and studied how this affects water loss.
View Article and Find Full Text PDFUnderdeveloped (small) embryos embedded in abundant endosperm tissue, and thus having morphological dormancy (MD) or morphophysiological dormancy (MPD), are considered to be the ancestral state in seed dormancy evolution. This trait is retained in the Apiaceae family, which provides excellent model systems for investigating the underpinning mechanisms. We investigated Apium graveolens (celery) MD by combined innovative imaging and embryo growth assays with the quantification of hormone metabolism, as well as the analysis of hormone and cell-wall related gene expression.
View Article and Find Full Text PDFEcdysteroids (ECs) are steroid hormones originally found in the animal kingdom where they function as insect molting hormones. Interestingly, a relatively high number of these substances can also be formed in plant cells. Moreover, ECs have certain regulatory effects on plant physiology, but their role in plants still requires further study.
View Article and Find Full Text PDFCarotenoids are important isoprenoids produced in the plastids of photosynthetic organisms that play key roles in photoprotection and antioxidative processes. β-Carotene is generated from lycopene by lycopene β-cyclase (LCYB). Previously, we demonstrated that the introduction of the Daucus carota (carrot) DcLCYB1 gene into tobacco (cv.
View Article and Find Full Text PDFPlant steroid alcohols, plant sterols, are essential components of cell membranes that perform many functions. Their most prominent function is maintaining membrane semipermeability and regulating its fluidity through their specific interaction with phospholipids and membrane proteins. This work is focused on the study of the interaction of two groups of plant sterols, brassinosteroids (BRs) and phytoecdysteroids (PE).
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