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1.
Plant J ; 2021 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-34510583

RESUMO

Underdeveloped (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. The integrated experimental results demonstrated that embryo growth occurred inside imbibed celery fruits in association with endosperm degradation, and that a critical embryo size was required for radicle emergence. The regulation of these processes depends on gene expression leading to gibberellin and indole-3-acetic acid (IAA) production by the embryo and on crosstalk between the fruit compartments. ABA degradation associated with distinct spatiotemporal patterns in ABA sensitivity control embryo growth, endosperm breakdown and radicle emergence. This complex interaction between gibberellins, IAA and ABA metabolism, and changes in the tissue-specific sensitivities to these hormones is distinct from non-MD seeds. We conclude that the embryo growth to reach the critical size and the associated endosperm breakdown inside MD fruits constitute a unique germination programme.

2.
Int J Mol Sci ; 22(15)2021 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-34360759

RESUMO

Salt and osmotic stress are the main abiotic stress factors affecting plant root growth and architecture. We investigated the effect of salt (100 mM NaCl) and osmotic (200 mM mannitol) stress on the auxin metabolome by UHPLC-MS/MS, auxin distribution by confocal microscopy, and transcript levels of selected genes by qRT-PCR in Arabidopsis thaliana ecotype Columbia-0 (Col-0) and DR5rev::GFP (DR5) line. During long-term stress (13 days), a stability of the auxin metabolome and a tendency to increase indole-3-acetic acid (IAA) were observed, especially during salt stress. Short-term stress (3 h) caused significant changes in the auxin metabolome, especially NaCl treatment resulted in a significant reduction of IAA. The data derived from auxin profiling were consistent with gene expressions showing the most striking changes in the transcripts of YUC, GH3, and UGT transcripts, suggesting disruption of auxin biosynthesis, but especially in the processes of amide and ester conjugation. These data were consistent with the auxin distribution observed in the DR5 line. Moreover, NaCl treatment caused a redistribution of auxin signals from the quiescent center and the inner layers of the root cap to the epidermal and cortical cells of the root elongation zone. The distribution of PIN proteins was also disrupted by salt stress; in particular, PIN2 was suppressed, even after 5 min of treatment. Based on our results, the DR5 line was more sensitive to the applied stresses than Col-0, although both lines showed similar trends in root morphology, as well as transcriptome and metabolome parameters under stress conditions.


Assuntos
Proteínas de Arabidopsis/biossíntese , Arabidopsis/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Ácidos Indolacéticos/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Estresse Salino/efeitos dos fármacos , Cloreto de Sódio/farmacologia
3.
Tree Physiol ; 41(6): 912-926, 2021 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-32348507

RESUMO

Vegetative propagation through somatic embryogenesis is an effective method to produce elite varieties and can be applied as a tool to study the response of plants to different stresses. Several studies show that environmental changes during embryogenesis could determine future plant development. Moreover, we previously reported that physical and chemical conditions during somatic embryogenesis can determine the protein, hormone and metabolite profiles, as well as the micromorphological and ultrastructural organization of embryonal masses and somatic embryos. In this sense, phytohormones are key players throughout the somatic embryogenesis process as well as during numerous stress-adaptation responses. In this work, we first applied different high-temperature regimes (30 °C, 4 weeks; 40 °C, 4 days; 50 °C, 5 min) during induction of Pinus radiata D. Don somatic embryogenesis, together with control temperature (23 °C). Then, the somatic plants regenerated from initiated embryogenic cell lines and cultivated in greenhouse conditions were subjected to drought stress and control treatments to evaluate survival, growth and several physiological traits (relative water content, water potential, photosynthesis, stomatal conductance and transpiration). Based on those preliminary results, even more extreme high-temperature regimes were applied during induction (40 °C, 4 h; 50 °C, 30 min; 60 °C, 5 min) and the corresponding cytokinin profiles of initiated embryonal masses from different lines were analysed. The results showed that the temperature regime during induction had delayed negative effects on drought resilience of somatic plants as indicated by survival, photosynthetic activity and water- use efficiency. However, high temperatures for extended periods of time enhanced subsequent plant growth in well-watered conditions. High-temperature regime treatments induced significant differences in the profile of total cytokinin bases, N6-isopentenyladenine, cis-zeatin riboside and trans-zeatin riboside. We concluded that phytohormones could be potential regulators of stress-response processes during initial steps of somatic embryogenesis and that they may have delayed implications in further developmental processes, determining the performance of the generated plants.


Assuntos
Pinus , Citocininas , Secas , Reguladores de Crescimento de Plantas , Temperatura
4.
Front Plant Sci ; 10: 450, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31031786

RESUMO

Soil salinity is severely affecting crop productivity in many countries, particularly in the Mediterranean area. To evaluate early plant responses to increased salinity and characterize tolerance markers, three important Brassica crops - Chinese cabbage (Brassica rapa ssp. pekinensis), white cabbage (B. oleracea var. capitata) and kale (B. oleracea var. acephala) were subjected to short-term (24 h) salt stress by exposing them to NaCl at concentrations of 50, 100, or 200 mM. Physiological (root growth, photosynthetic performance parameters, and Na+/K+ ratio) and biochemical parameters (proline content and lipid peroxidation as indicated by malondialdehyde, MDA, levels) in the plants' roots and leaves were then measured. Photosynthetic parameters such as the total performance index PItotal (describing the overall efficiency of PSI, PSII and the intersystem electron transport chain) appeared to be the most salinity-sensitive parameter and informative stress marker. This parameter was decreased more strongly in Chinese cabbage than in white cabbage and kale. It indicated that salinity reduced the capacity of the photosynthetic system for efficient energy conversion, particularly in Chinese cabbage. In parallel with the photosynthetic impairments, the Na+/K+ ratio was highest in Chinese cabbage leaves and lowest in kale leaves while kale root is able to keep high Na+/K+ ratio without a significant increase in MDA. Thus Na+/K+ ratio, high in root and low in leaves accompanying with low MDA level is an informative marker of salinity tolerance. The crops' tolerance was positively correlated with levels of the stress hormone abscisic acid (ABA) and negatively correlated with levels of jasmonic acid (JA), and jasmonoyl-L-isoleucine (JA-Ile). Furthermore, salinity induced contrasting changes in levels of the growth-promoting hormones brassinosteroids (BRs). The crop's tolerance was positively correlated with levels of BR precursor typhasterol while negatively with the active BR brassinolide. Principal Component Analysis revealed correlations in observed changes in phytohormones, biochemical, and physiological parameters. Overall, the results show that kale is the most tolerant of the three species and Chinese cabbage the most sensitive to salt stress, and provide holistic indications of the spectrum of tolerance mechanisms involved.

5.
Int J Mol Sci ; 19(10)2018 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-30241414

RESUMO

Drought is one of the major abiotic stresses affecting the productivity of Brassica crops. To understand the role of phytohormones in drought tolerance, we subjected Chinese cabbage (B. rapa ssp. pekinensis), white cabbage (B. oleracea var. capitata), and kale (B. oleracea var. acephala) to drought and examined the stress response on the physiological, biochemical and hormonal levels. The phytohormones abscisic acid (ABA), auxin indole-3-acetic acid (IAA), brassinosteroids (BRs), cytokinins (CKs), jasmonates (JAs), and salicylic acid (SA) were analyzed by ultra-high-performance liquid chromatography⁻tandem mass spectrometry (UHPLC-MS/MS). Based on the physiological and biochemical markers the Chinese cabbage exhibited the lowest tolerance, followed by the white cabbage, while the kale appeared to be the most tolerant to drought. The drought tolerance of the kale correlated with increased levels of SA, ABA, IAA, CKs iP(R) and cZ(R), and typhasterol (TY), a precursor of active BRs. In contrast, the drought sensitivity of the Chinese cabbage correlated with a significant increase in ABA, JAs and the active BRs castasterol (CS) and brassinolide (BL). The moderately tolerant white cabbage, positioned between the kale and Chinese cabbage, showed more similarity in terms of the phytohormone patterns with the kale. We concluded that the drought tolerance in Brassicaceae is mostly determined by the increased endogenous levels of IAA, CKs, ABA and SA and the decreased levels of active BRs.


Assuntos
Brassica/metabolismo , Secas , Regulação da Expressão Gênica de Plantas , Reguladores de Crescimento de Plantas/metabolismo , Proteínas de Plantas/genética , Estresse Fisiológico , Brassica/classificação , Brassica/genética , Perfilação da Expressão Gênica , Proteínas de Plantas/metabolismo
6.
Food Chem ; 269: 96-102, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30100490

RESUMO

Five Brassicaceae sprouts (white cabbage, kale, broccoli, Chinese cabbage, arugula) were comparatively analyzed based on phytochemicals (polyphenols, glucosinolates, carotenoids, chlorophylls, ascorbic acid) content and accompanying enzymes associated with phytochemical stability and bioavailability (peroxidases, myrosinase, and polyphenol-oxidase) that consequently impact food quality. Significantly high content of polyphenols and glucosinolates, as well as a high antioxidant activity were found in white cabbage, followed by kale sprouts. In addition, white cabbage contained higher amount of fibers and lower polyphenol-oxidase activity which potentially indicates prevention of browning and consequently better sprout quality. Arugula and broccoli showed higher activity of myrosinase that may result in higher bioavailability of active glucosinolates forms. According to our data, sprouts are cheap, easy- and fast-growing source of phytochemicals but also they are characterized by different endogenous enzymes activity. Consequently, this parameter should also be taken into consideration in the studies related to the health benefits of the plant-based food.


Assuntos
Brassica/química , Brassica/enzimologia , Qualidade dos Alimentos , Compostos Fitoquímicos/análise , Disponibilidade Biológica , Catecol Oxidase/metabolismo , Análise de Alimentos , Glucosinolatos , Glicosídeo Hidrolases/metabolismo , Humanos , Peroxidases/metabolismo , Compostos Fitoquímicos/farmacocinética
7.
Plant Physiol Biochem ; 125: 74-84, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29427890

RESUMO

Salinity is one of major abiotic stresses affecting Brassica crop production. Here we present investigations into the physiological, biochemical, and hormonal components of the short-term salinity stress response in Chinese cabbage seedlings, with particular emphasis on the biosynthesis and metabolism of auxin indole-3-acetic acid (IAA). Upon salinity treatments (50-200 mM NaCl) IAA level was elevated in a dose dependent manner reaching 1.6-fold increase at the most severe salt treatment in comparison to the control. IAA precursor profiling suggested that salinity activated the indole-3-acetamide and indole-3-acetaldoxime biosynthetic pathways while suppressing the indole-3-pyruvic acid pathway. Levels of the IAA catabolites 2-oxoindole-3-acetic acid and indole-3-acetic acid-aspartate increased 1.7- and 2.0-fold, respectively, under the most severe treatment, in parallel with those of IAA. Conversely, levels of the ester conjugate indole-3-acetyl-1-O-ß-d-glucose and its catabolite 2-oxoindole-3-acetyl-1-O-ß-d-glucose decreased 2.5- and 7.0-fold, respectively. The concentrations of stress hormones including jasmonic acid and jasmonoyl-isoleucine (JA and JA-Ile), salicylic acid (SA) and abscisic acid (ABA) confirmed the stress induced by salt treatment: levels of JA and JA-Ile increased strongly under the mildest treatment, ABA only increased under the most severe treatment, and SA levels decreased dose-dependently. These hormonal changes were related to the observed changes in biochemical stress markers upon salt treatments: reductions in seedling fresh weight and root growth, decreased photosynthesis rate, increased levels of reactive oxygen species, and elevated proline content and the Na+/K+ ratio. Correlations among auxin profile and biochemical stress markers were discussed based on Pearson's coefficients and principal component analysis (PCA).


Assuntos
Brassica rapa/metabolismo , Ácidos Indolacéticos/metabolismo , Plântula/metabolismo , Cloreto de Sódio/farmacologia , Estresse Fisiológico/efeitos dos fármacos
8.
Plant Cell Rep ; 32(7): 1031-42, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23508255

RESUMO

KEY MESSAGE : Stress hormones, particularly jasmonic acid, influenced root growth, auxin levels, and transcription of auxin amidohydrolase BrIAR3 in Brassica rapa seedlings, while auxin conjugate synthetases BrGH3.1 and BrGH3.9 were down-regulated by all treatments. The influence of stress hormones: jasmonic acid (JA), salicylic acid (SA), and abscisic acid (ABA) on 1-day-old seedlings of Chinese cabbage (Brassica rapa L. ssp. pekinensis) was investigated with particular focus on auxin levels and the regulation of reversible auxin conjugation as a mechanism of auxin homeostasis. At the physiological level, stress hormones inhibited root growth, where JA was the most prominent inhibitor with an IC50 value 3.1 µM, which is one and two orders of magnitude lower than that found for ABA and SA, respectively. JA treatment significantly increased the total auxin content, by induction of free and conjugated forms. Also, the stress hormones affected the transcription of genes involved in the process of the reversible auxin conjugation: auxin amidohydrolases BrIAR3 and BrILL2, and auxin conjugate synthetases BrGH3.1 and BrGH3.9. JA treatment increased the transcript level of BrIAR3 two-fold, while it did not affect the transcription of BrILL2. SA and ABA down-regulated the transcription of both auxin amidohydrolase genes by 30 %. Transcription of both auxin conjugate synthetases was significantly down-regulated by all treatments by 30-70 %. Among the investigated biochemical stress markers, glutathione along with protein carbonylation appeared the most affected upon treatments. The redox status of the seedlings was shifted to the more oxidized state upon JA and ABA treatments, whereas SA caused more reduced redox state in comparison to the control. The principal component analysis visualized relationship among auxin and stress parameters upon treatments. Accordingly, the role of auxin in stress response of Brassica seedlings was discussed.


Assuntos
Brassica/metabolismo , Ácidos Indolacéticos/metabolismo , Plântula/metabolismo , Ácido Abscísico/metabolismo , Ciclopentanos/metabolismo , Glutationa/metabolismo , Peroxidação de Lipídeos , Oxilipinas/metabolismo , Fenóis/metabolismo , Raízes de Plantas/metabolismo , Ácido Salicílico/metabolismo
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