Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 34
Filtrar
1.
Plant Physiol ; 192(2): 1584-1602, 2023 05 31.
Artículo en Inglés | MEDLINE | ID: mdl-36861637

RESUMEN

The 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. However, the photoreceptors involved in this process in A. arabicum remain unknown. Here, we screened a mutant collection of A. arabicum and identified koy-1, a mutant that lost light inhibition of germination due to a deletion in the promoter of HEME OXYGENASE 1, the gene for a key enzyme in the biosynthesis of the phytochrome chromophore. koy-1 seeds were unresponsive to red- and far-red light and hyposensitive under white light. Comparison of hormone and gene expression between wild type and koy-1 revealed that very low light fluence stimulates germination, while high irradiance of red and far-red light is inhibitory, indicating a dual role of phytochromes in light-regulated seed germination. The mutation also affects the ratio between the 2 fruit morphs of A. arabicum, suggesting that light reception via phytochromes can fine-tune several parameters of propagation in adaptation to conditions in the habitat.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Brassicaceae , Fitocromo , Fitocromo/genética , Fitocromo/metabolismo , Arabidopsis/metabolismo , Germinación/genética , Brassicaceae/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Semillas/genética , Hormonas/metabolismo
2.
Planta ; 258(2): 25, 2023 Jun 23.
Artículo en Inglés | MEDLINE | ID: mdl-37351659

RESUMEN

MAIN CONCLUSION: We 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. In this study, we have measured the endogenous levels of ABA and GAs comparatively between wild and domesticated pea seeds during their development. We have shown that wild seeds contained more ABA than domesticated ones, which could be important for preparing the seeds for the period of dormancy. ABA was catabolised particularly by an 8´-hydroxylation pathway, and dihydrophaseic acid was the main catabolite in seed coats as well as embryos. Besides, the seed coats of wild and pigmented cultivated genotypes were characterised by a broader spectrum of bioactive GAs compared to non-pigmented domesticated seeds. GAs in both seed coat and embryo were synthesized mainly by a 13-hydroxylation pathway, with GA29 being the most abundant in the seed coat and GA20 in the embryos. Measuring seed water content and water loss indicated domesticated pea seeds´ desiccation was slower than that of wild pea seeds. Altogether, we showed that pea domestication led to a change in bioactive GA composition and a lower ABA content during seed development.


Asunto(s)
Ácido Abscísico , Arabidopsis , Ácido Abscísico/metabolismo , Giberelinas/metabolismo , Pisum sativum/genética , Pisum sativum/metabolismo , Domesticación , Germinación , Semillas , Latencia en las Plantas/genética , Arabidopsis/genética
3.
Plant Cell Environ ; 46(6): 1785-1804, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-36760106

RESUMEN

Perennial 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. tremuloides) compromising the apex releases para-dormancy, whereas endo-dormancy requires chilling. ABA and GA are implicated in both phenomena. To untangle their roles, we blocked ABA biosynthesis with fluridone (FD), which significantly reduced ABA levels, downregulated GA-deactivation genes, upregulated the major GA3ox-biosynthetic genes, and initiated branching. Comprehensive GA-metabolite analyses suggested that FD treatment shifted GA production to the non-13-hydroxylation pathway, enhancing GA4 function. Applied ABA counteracted FD effects on GA metabolism and downregulated several GA3/4 -inducible α- and γ-clade 1,3-ß-glucanases that hydrolyze callose at plasmodesmata (PD), thereby enhancing PD-callose accumulation. Remarkably, ABA-deficient plants repressed GA4 biosynthesis and established endo-dormancy like controls but showed increased stress sensitivity. Repression of GA4 biosynthesis involved short-day induced DNA methylation events within the GA3ox2 promoter. In conclusion, the results cast new light on the roles of ABA and GA in dormancy cycling. In para-dormancy, PD-callose turnover is antagonized by ABA, whereas in short-day conditions, lack of GA4 biosynthesis promotes callose deposition that is structurally persistent throughout endo-dormancy.


Asunto(s)
Giberelinas , Populus , Giberelinas/metabolismo , Regulación de la Expresión Génica de las Plantas , Populus/metabolismo , Ácido Abscísico/metabolismo , Latencia en las Plantas/genética , Semillas/metabolismo
4.
Plant Cell Environ ; 45(4): 1315-1332, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35064681

RESUMEN

The 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. Transcriptome analysis revealed distinct gene expression patterns in the different temperature regimes and upon secondary dormancy induction and maintenance. The chilling caused reduced expression of cell wall remodelling protein genes required for embryo cell elongation growth and endosperm weakening, as well as increased expression of seed maturation genes, such as for late embryogenesis abundant proteins. A model integrating the hormonal signalling and master regulator expression with the temperature-control of seed dormancy and maturation programmes is proposed. The revealed mechanisms of the cold-induced secondary dormancy are important for climate-smart agriculture and food security.


Asunto(s)
Beta vulgaris , Ácido Abscísico/metabolismo , Beta vulgaris/genética , Germinación/fisiología , Latencia en las Plantas/genética , Semillas/fisiología
5.
Plant J ; 103(6): 1967-1984, 2020 09.
Artículo en Inglés | MEDLINE | ID: mdl-32623777

RESUMEN

Because carotenoids act as accessory pigments in photosynthesis, play a key photoprotective role and are of major nutritional importance, carotenogenesis has been a target for crop improvement. Although carotenoids are important precursors of phytohormones, previous genetic manipulations reported little if any effects on biomass production and plant development, but resulted in specific modifications in carotenoid content. Unexpectedly, the expression of the carrot lycopene ß-cyclase (DcLCYB1) in Nicotiana tabacum cv. Xanthi not only resulted in increased carotenoid accumulation, but also in altered plant architecture characterized by longer internodes, faster plant growth, early flowering and increased biomass. Here, we have challenged these transformants with a range of growth conditions to determine the robustness of their phenotype and analyze the underlying mechanisms. Transgenic DcLCYB1 lines showed increased transcript levels of key genes involved in carotenoid, chlorophyll, gibberellin (GA) and abscisic acid (ABA) biosynthesis, but also in photosynthesis-related genes. Accordingly, their carotenoid, chlorophyll, ABA and GA contents were increased. Hormone application and inhibitor experiments confirmed the key role of altered GA/ABA contents in the growth phenotype. Because the longer internodes reduce shading of mature leaves, induction of leaf senescence was delayed, and mature leaves maintained a high photosynthetic capacity. This increased total plant assimilation, as reflected in higher plant yields under both fully controlled constant and fluctuating light, and in non-controlled conditions. Furthermore, our data are a warning that engineering of isoprenoid metabolism can cause complex changes in phytohormone homeostasis and therefore plant development, which have not been sufficiently considered in previous studies.


Asunto(s)
Carotenoides/metabolismo , Genes de Plantas/fisiología , Nicotiana/crecimiento & desarrollo , Fotosíntesis/genética , Ácido Abscísico/metabolismo , Daucus carota/genética , Regulación de la Expresión Génica de las Plantas/genética , Genes de Plantas/genética , Giberelinas/metabolismo , Redes y Vías Metabólicas/genética , Fotosíntesis/fisiología , Reguladores del Crecimiento de las Plantas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/fisiología , Plantas Modificadas Genéticamente , Nicotiana/anatomía & histología , Nicotiana/metabolismo , Nicotiana/fisiología , Regulación hacia Arriba
6.
J Exp Bot ; 72(18): 6447-6466, 2021 09 30.
Artículo en Inglés | MEDLINE | ID: mdl-34107028

RESUMEN

Chloroplast-localized adenosine-5'-phosphosulphate reductase (APR) generates sulfite and plays a pivotal role in reduction of sulfate to cysteine. The peroxisome-localized sulfite oxidase (SO) oxidizes excess sulfite to sulfate. Arabidopsis wild type, SO RNA-interference (SO Ri) and SO overexpression (SO OE) transgenic lines infiltrated with sulfite showed increased water loss in SO Ri plants, and smaller stomatal apertures in SO OE plants compared with wild-type plants. Sulfite application also limited sulfate and abscisic acid-induced stomatal closure in wild type and SO Ri. The increases in APR activity in response to sulfite infiltration into wild type and SO Ri leaves resulted in an increase in endogenous sulfite, indicating that APR has an important role in sulfite-induced increases in stomatal aperture. Sulfite-induced H2O2 generation by NADPH oxidase led to enhanced APR expression and sulfite production. Suppression of APR by inhibiting NADPH oxidase and glutathione reductase2 (GR2), or mutation in APR2 or GR2, resulted in a decrease in sulfite production and stomatal apertures. The importance of APR and SO and the significance of sulfite concentrations in water loss were further demonstrated during rapid, harsh drought stress in root-detached wild-type, gr2 and SO transgenic plants. Our results demonstrate the role of SO in sulfite homeostasis in relation to water consumption in well-watered plants.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Oxidorreductasas actuantes sobre Donantes de Grupos Sulfuro , Sulfito-Oxidasa , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Glutatión Reductasa , Peróxido de Hidrógeno , Oxidorreductasas actuantes sobre Donantes de Grupos Sulfuro/genética , Sulfito-Oxidasa/genética , Sulfitos , Agua
7.
J Exp Bot ; 72(7): 2544-2569, 2021 03 29.
Artículo en Inglés | MEDLINE | ID: mdl-33484250

RESUMEN

Carotenoids are important isoprenoids produced in the plastids of photosynthetic organisms that play key roles in photoprotection and antioxidative processes. ß-Carotene is generated from lycopene by lycopene ß-cyclase (LCYB). Previously, we demonstrated that the introduction of the Daucus carota (carrot) DcLCYB1 gene into tobacco (cv. Xanthi) resulted in increased levels of abscisic acid (ABA) and especially gibberellins (GAs), resulting in increased plant yield. In order to understand this phenomenon prior to exporting this genetic strategy to crops, we generated tobacco (Nicotiana tabacum cv. Petit Havana) mutants that exhibited a wide range of LCYB expression. Transplastomic plants expressing DcLCYB1 at high levels showed a wild-type-like growth, even though their pigment content was increased and their leaf GA1 content was reduced. RNA interference (RNAi) NtLCYB lines showed different reductions in NtLCYB transcript abundance, correlating with reduced pigment content and plant variegation. Photosynthesis (leaf absorptance, Fv/Fm, and light-saturated capacity of linear electron transport) and plant growth were impaired. Remarkably, drastic changes in phytohormone content also occurred in the RNAi lines. However, external application of phytohormones was not sufficient to rescue these phenotypes, suggesting that altered photosynthetic efficiency might be another important factor explaining their reduced biomass. These results show that LCYB expression influences plant biomass by different mechanisms and suggests thresholds for LCYB expression levels that might be beneficial or detrimental for plant growth.


Asunto(s)
Liasas Intramoleculares , Nicotiana , Carotenoides , Regulación de la Expresión Génica de las Plantas , Liasas Intramoleculares/genética , Liasas Intramoleculares/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/metabolismo , Nicotiana/genética , Nicotiana/metabolismo
8.
New Phytol ; 225(4): 1681-1698, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31597191

RESUMEN

Salinity stress limits plant growth and has a major impact on agricultural productivity. Here, we identify NAC transcription factor SlTAF1 as a regulator of salt tolerance in cultivated tomato (Solanum lycopersicum). While overexpression of SlTAF1 improves salinity tolerance compared with wild-type, lowering SlTAF1 expression causes stronger salinity-induced damage. Under salt stress, shoots of SlTAF1 knockdown plants accumulate more toxic Na+ ions, while SlTAF1 overexpressors accumulate less ions, in accordance with an altered expression of the Na+ transporter genes SlHKT1;1 and SlHKT1;2. Furthermore, stomatal conductance and pore area are increased in SlTAF1 knockdown plants during salinity stress, but decreased in SlTAF1 overexpressors. We identified stress-related transcription factor, abscisic acid metabolism and defence-related genes as potential direct targets of SlTAF1, correlating it with reactive oxygen species scavenging capacity and changes in hormonal response. Salinity-induced changes in tricarboxylic acid cycle intermediates and amino acids are more pronounced in SlTAF1 knockdown than wild-type plants, but less so in SlTAF1 overexpressors. The osmoprotectant proline accumulates more in SlTAF1 overexpressors than knockdown plants. In summary, SlTAF1 controls the tomato's response to salinity stress by combating both osmotic stress and ion toxicity, highlighting this gene as a promising candidate for the future breeding of stress-tolerant crops.


Asunto(s)
Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Proteínas de Plantas/metabolismo , Estrés Salino/fisiología , Solanum lycopersicum/metabolismo , Técnicas de Silenciamiento del Gen , Homeostasis , Transporte Iónico/genética , Transporte Iónico/fisiología , Solanum lycopersicum/genética , Proteínas de Plantas/genética , Raíces de Plantas , Brotes de la Planta , Potasio , Estrés Salino/genética , Sodio , Cloruro de Sodio/toxicidad
9.
Plant Cell Environ ; 43(7): 1613-1624, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32196123

RESUMEN

miR156 is a conserved microRNA whose role and induction mechanisms under stress are poorly known. Strigolactones are phytohormones needed in shoots for drought acclimation. They promote stomatal closure ABA-dependently and independently; however, downstream effectors for the former have not been identified. Linkage between miR156 and strigolactones under stress has not been reported. We compared ABA accumulation and sensitivity as well as performances of wt and miR156-overexpressing (miR156-oe) tomato plants during drought. We also quantified miR156 levels in wt, strigolactone-depleted and strigolactone-treated plants, exposed to drought stress. Under irrigated conditions, miR156 overexpression and strigolactone treatment led to lower stomatal conductance and higher ABA sensitivity. Exogenous strigolactones were sufficient for miR156 accumulation in leaves, while endogenous strigolactones were required for miR156 induction by drought. The "after-effect" of drought, by which stomata do not completely re-open after rewatering, was enhanced by both strigolactones and miR156. The transcript profiles of several miR156 targets were altered in strigolactone-depleted plants. Our results show that strigolactones act as a molecular link between drought and miR156 in tomato, and identify miR156 as a mediator of ABA-dependent effect of strigolactones on the after-effect of drought on stomata. Thus, we provide insights into both strigolactone and miR156 action on stomata.


Asunto(s)
Compuestos Heterocíclicos con 3 Anillos/metabolismo , Lactonas/metabolismo , MicroARNs/fisiología , Estomas de Plantas/fisiología , ARN de Planta/fisiología , Solanum lycopersicum/fisiología , Ácido Abscísico/metabolismo , Deshidratación , Solanum lycopersicum/metabolismo , MicroARNs/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , ARN de Planta/metabolismo
10.
J Exp Bot ; 71(1): 247-257, 2020 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-31504736

RESUMEN

Photosynthetic activity is affected by exogenous and endogenous inputs, including source-sink balance. Reducing the source to sink ratio by partial defoliation or heavy shading resulted in significant elevation of the photosynthetic rate in the remaining leaf of tomato plants within 3 d. The remaining leaf turned deep green, and its area increased by almost 3-fold within 7 d. Analyses of photosynthetic activity established up-regulation due to increased carbon fixation activity in the remaining leaf, rather than due to altered water balance. Moreover, senescence of the remaining leaf was significantly inhibited. As expected, carbohydrate concentration was lower in the remaining leaf than in the control leaves; however, expression of genes involved in sucrose export was significantly lower. These results suggest that the accumulated fixed carbohydrates were primarily devoted to increasing the size of the remaining leaf. Detailed analyses of the cytokinin content indicated that partial defoliation alters cytokinin biosynthesis in the roots, resulting in a higher concentration of trans-zeatin riboside, the major xylem-translocated molecule, and a higher concentration of total cytokinin in the remaining leaf. Together, our findings suggest that trans-zeatin riboside acts as a signal molecule that traffics from the root to the remaining leaf to alter gene expression and elevate photosynthetic activity.


Asunto(s)
Citocininas/fisiología , Fotosíntesis , Hojas de la Planta/metabolismo , Raíces de Plantas/fisiología , Brotes de la Planta/fisiología , Transducción de Señal , Solanum lycopersicum/fisiología
11.
Genes Dev ; 26(17): 1984-96, 2012 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-22948663

RESUMEN

Phytochromes phyB and phyA mediate a remarkable developmental switch whereby, early upon seed imbibition, canopy light prevents phyB-dependent germination, whereas later on, it stimulates phyA-dependent germination. Using a seed coat bedding assay where the growth of dissected embryos is monitored under the influence of dissected endosperm, allowing combinatorial use of mutant embryos and endosperm, we show that canopy light specifically inactivates phyB activity in the endosperm to override phyA-dependent signaling in the embryo. This interference involves abscisic acid (ABA) release from the endosperm and distinct spatial activities of phytochrome signaling components. Under the canopy, endospermic ABA opposes phyA signaling through the transcription factor (TF) ABI5, which shares with the TF PIF1 several target genes that negatively regulate germination in the embryo. ABI5 enhances the expression of phytochrome signaling genes PIF1, SOMNUS, GAI, and RGA, but also of ABA and gibberellic acid (GA) metabolic genes. Over time, weaker ABA-dependent responses eventually enable phyA-dependent germination, a distinct type of germination driven solely by embryonic growth.


Asunto(s)
Arabidopsis/embriología , Arabidopsis/metabolismo , Germinación , Fitocromo A/metabolismo , Fitocromo B/metabolismo , Semillas/embriología , Ácido Abscísico/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Endospermo/metabolismo , Regulación de la Expresión Génica de las Plantas , Reguladores del Crecimiento de las Plantas/metabolismo , Regiones Promotoras Genéticas , Semillas/metabolismo , Transducción de Señal
12.
Plant J ; 94(1): 105-121, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29385297

RESUMEN

We studied the effect of reducing the levels of the mitochondrial electron carrier cytochrome c (CYTc) in Arabidopsis thaliana. Plants with CYTc deficiency have delayed growth and development, and reach flowering several days later than the wild-type but with the same number of leaves. CYTc-deficient plants accumulate starch and glucose during the day, and contain lower levels of active gibberellins (GA) and higher levels of DELLA proteins, involved in GA signaling. GA treatment abolishes the developmental delay and reduces glucose accumulation in CYTc-deficient plants, which also show a lower raise in ATP levels in response to glucose. Treatment of wild-type plants with inhibitors of mitochondrial energy production limits plant growth and increases the levels of DELLA proteins, thus mimicking the effects of CYTc deficiency. In addition, an increase in the amount of CYTc decreases DELLA protein levels and expedites growth, and this depends on active GA synthesis. We conclude that CYTc levels impinge on the activity of the GA pathway, most likely through changes in mitochondrial energy production. In this way, hormone-dependent growth would be coupled to the activity of components of the mitochondrial respiratory chain.


Asunto(s)
Arabidopsis/crecimiento & desarrollo , Citocromos c/metabolismo , Giberelinas/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Citocromos c/deficiencia , Citocromos c/fisiología , Metabolismo Energético , Regulación de la Expresión Génica de las Plantas , Giberelinas/fisiología , Glucosa/metabolismo , Homeostasis , Mitocondrias/metabolismo , Almidón/metabolismo
13.
Planta ; 250(5): 1717-1729, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31414204

RESUMEN

MAIN CONCLUSION: Seed-processing technologies such as polishing and washing enhance crop seed quality by limited removal of the outer layers and by leaching. Combined, this removes chemical compounds that inhibit germination. Industrial processing to deliver high-quality commercial seed includes removing chemical inhibitors of germination, and is essential to produce fresh sprouts, achieve vigorous crop establishment, and high yield potential in the field. Sugar beet (Beta vulgaris subsp. vulgaris var. altissima Doell.), the main sugar source of the temperate agricultural zone, routinely undergoes several processing steps during seed production to improve germination performance and seedling growth. Germination assays and seedling phenotyping was carried out on unprocessed, and processed (polished and washed) sugar beet fruits. Pericarp-derived solutes, known to inhibit germination, were tested in germination assays and their osmolality and conductivity assessed (ions). Abscisic acid (ABA) and ABA metabolites were quantified in both the true seed and pericarp tissue using UPLC-ESI(+)-MS/MS. Physical changes in the pericarp structures were assessed using scanning electron microscopy (SEM). We found that polishing and washing of the sugar beet fruits both had a positive effect on germination performance and seedling phenotype, and when combined, this positive effect was stronger. The mechanical action of polishing removed the outer pericarp (fruit coat) tissue (parenchyma), leaving the inner tissue (sclerenchyma) unaltered, as revealed by SEM. Polishing as well as washing removed germination inhibitors from the pericarp, specifically, ABA, ABA metabolites, and ions. Understanding the biochemistry underpinning the effectiveness of these processing treatments is key to driving further innovations in commercial seed quality.


Asunto(s)
Ácido Abscísico/metabolismo , Beta vulgaris/crecimiento & desarrollo , Reguladores del Crecimiento de las Plantas/metabolismo , Beta vulgaris/fisiología , Bioquímica , Germinación , Semillas/crecimiento & desarrollo , Semillas/fisiología , Espectrometría de Masas en Tándem
14.
Plant Physiol ; 177(3): 1286-1302, 2018 07.
Artículo en Inglés | MEDLINE | ID: mdl-29760199

RESUMEN

Leaf senescence is an essential physiological process in plants that supports the recycling of nitrogen and other nutrients to support the growth of developing organs, including young leaves, seeds, and fruits. Thus, the regulation of senescence is crucial for evolutionary success in wild populations and for increasing yield in crops. Here, we describe the influence of a NAC transcription factor, SlNAP2 (Solanum lycopersicum NAC-like, activated by Apetala3/Pistillata), that controls both leaf senescence and fruit yield in tomato (S. lycopersicum). SlNAP2 expression increases during age-dependent and dark-induced leaf senescence. We demonstrate that SlNAP2 activates SlSAG113 (S. lycopersicum SENESCENCE-ASSOCIATED GENE113), a homolog of Arabidopsis (Arabidopsis thaliana) SAG113, chlorophyll degradation genes such as SlSGR1 (S. lycopersicum senescence-inducible chloroplast stay-green protein 1) and SlPAO (S. lycopersicum pheide a oxygenase), and other downstream targets by directly binding to their promoters, thereby promoting leaf senescence. Furthermore, SlNAP2 directly controls the expression of genes important for abscisic acid (ABA) biosynthesis, S. lycopersicum 9-cis-epoxycarotenoid dioxygenase 1 (SlNCED1); transport, S. lycopersicum ABC transporter G family member 40 (SlABCG40); and degradation, S. lycopersicum ABA 8'-hydroxylase (SlCYP707A2), indicating that SlNAP2 has a complex role in establishing ABA homeostasis during leaf senescence. Inhibiting SlNAP2 expression in transgenic tomato plants impedes leaf senescence but enhances fruit yield and sugar content likely due to prolonged leaf photosynthesis in aging tomato plants. Our data indicate that SlNAP2 has a central role in controlling leaf senescence and fruit yield in tomato.


Asunto(s)
Frutas/crecimiento & desarrollo , Hojas de la Planta/fisiología , Proteínas de Plantas/metabolismo , Solanum lycopersicum/crecimiento & desarrollo , Factores de Transcripción/metabolismo , Ácido Abscísico/genética , Ácido Abscísico/metabolismo , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , Oscuridad , Dioxigenasas/genética , Dioxigenasas/metabolismo , Frutas/genética , Regulación de la Expresión Génica de las Plantas , Técnicas de Silenciamiento del Gen , Solanum lycopersicum/genética , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Factores de Transcripción/genética
15.
J Exp Bot ; 70(12): 3313-3328, 2019 06 28.
Artículo en Inglés | MEDLINE | ID: mdl-30949700

RESUMEN

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.


Asunto(s)
Brassicaceae/fisiología , Expresión Génica/efectos de la radiación , Genes de Plantas , Germinación/efectos de la radiación , Luz Solar , Ácido Abscísico/metabolismo , Brassicaceae/efectos de la radiación , Giberelinas/metabolismo , Transcriptoma/efectos de los fármacos
16.
Plant Cell ; 28(2): 505-20, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26764377

RESUMEN

In eukaryotes, the decapping machinery is highly conserved and plays an essential role in controlling mRNA stability, a key step in the regulation of gene expression. Yet, the role of mRNA decapping in shaping gene expression profiles in response to environmental cues and the operating molecular mechanisms are poorly understood. Here, we provide genetic and molecular evidence that a component of the decapping machinery, the LSM1-7 complex, plays a critical role in plant tolerance to abiotic stresses. Our results demonstrate that, depending on the stress, the complex from Arabidopsis thaliana interacts with different selected stress-inducible transcripts targeting them for decapping and subsequent degradation. This interaction ensures the correct turnover of the target transcripts and, consequently, the appropriate patterns of downstream stress-responsive gene expression that are required for plant adaptation. Remarkably, among the selected target transcripts of the LSM1-7 complex are those encoding NCED3 and NCED5, two key enzymes in abscisic acid (ABA) biosynthesis. We demonstrate that the complex modulates ABA levels in Arabidopsis exposed to cold and high salt by differentially controlling NCED3 and NCED5 mRNA turnover, which represents a new layer of regulation in ABA biosynthesis in response to abiotic stress. Our findings uncover an unanticipated functional plasticity of the mRNA decapping machinery to modulate the relationship between plants and their environment.


Asunto(s)
Adaptación Fisiológica , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Endorribonucleasas/metabolismo , Regulación de la Expresión Génica de las Plantas , Modelos Biológicos , Ácido Abscísico/metabolismo , Arabidopsis/fisiología , Proteínas de Arabidopsis/genética , Frío , Endorribonucleasas/genética , Genes Reporteros , Reguladores del Crecimiento de las Plantas/metabolismo , Plantas Modificadas Genéticamente , ARN Mensajero/genética , ARN Mensajero/metabolismo , Cloruro de Sodio/metabolismo , Estrés Fisiológico
17.
Proc Natl Acad Sci U S A ; 111(34): E3571-80, 2014 Aug 26.
Artículo en Inglés | MEDLINE | ID: mdl-25114251

RESUMEN

Seed germination is an important life-cycle transition because it determines subsequent plant survival and reproductive success. To detect optimal spatiotemporal conditions for germination, seeds act as sophisticated environmental sensors integrating information such as ambient temperature. Here we show that the delay of germination 1 (DOG1) gene, known for providing dormancy adaptation to distinct environments, determines the optimal temperature for seed germination. By reciprocal gene-swapping experiments between Brassicaceae species we show that the DOG1-mediated dormancy mechanism is conserved. Biomechanical analyses show that this mechanism regulates the material properties of the endosperm, a seed tissue layer acting as germination barrier to control coat dormancy. We found that DOG1 inhibits the expression of gibberellin (GA)-regulated genes encoding cell-wall remodeling proteins in a temperature-dependent manner. Furthermore we demonstrate that DOG1 causes temperature-dependent alterations in the seed GA metabolism. These alterations in hormone metabolism are brought about by the temperature-dependent differential expression of genes encoding key enzymes of the GA biosynthetic pathway. These effects of DOG1 lead to a temperature-dependent control of endosperm weakening and determine the optimal temperature for germination. The conserved DOG1-mediated coat-dormancy mechanism provides a highly adaptable temperature-sensing mechanism to control the timing of germination.


Asunto(s)
Proteínas de Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Arabidopsis/genética , Lepidium sativum/crecimiento & desarrollo , Lepidium sativum/genética , Arabidopsis/fisiología , Fenómenos Biomecánicos , Secuencia Conservada , Diploidia , Regulación del Desarrollo de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Germinación/genética , Germinación/fisiología , Giberelinas/metabolismo , Lepidium sativum/fisiología , Datos de Secuencia Molecular , Mutación , Latencia en las Plantas/genética , Latencia en las Plantas/fisiología , Plantas Modificadas Genéticamente , Semillas/crecimiento & desarrollo , Temperatura
18.
Plant Cell Rep ; 35(1): 77-89, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26403461

RESUMEN

KEY MESSAGE: Habituated embryogenic line of pumpkin contained more CKs and IAA, but less ABA than the non-habituated line. Pronounced hypomethylation correlated with the absence of 2,4-D, addition of 5-azaC, and the process of habituation. A comparative analysis between habituated and non-habituated embryogenic cultures of pumpkin (Cucurbita pepo L.) in relation to endogenous phytohormones, global DNA methylation, and developmental and regeneration capacities of the cultures was conducted. The analysis revealed more cytokinins (CKs) and indole-3-acetic acid (IAA), but less abscisic acid (ABA) in the habituated HEC line than in the non-habituated DEC line. Ribosides and ribotides were the most abundant CK forms in both HEC and DEC lines (75.9 and 57.6 %, respectively). HEC contained more free-base CKs (5.8 vs. 3.2 %), whereas DEC contained considerably more O-glycosides (39.1 vs. 18.3 %). Although prevalence of IAA was common for both lines, relative ratio of CKs and ABA differed between DEC and HEC lines. ABA was prevailing over CKs in DEC, while CKs prevailed over ABA in HEC line. Taking into account the importance of ABA for embryo maturation, the reduced endogenous ABA content in HEC line might be the reason for a 5-fold reduction in regeneration capacity compared to DEC. Both habituated and non-habituated embryogenic lines were highly methylated in the presence of 2,4-dichlorophenoxyacetic acid (2,4-D). Pronounced hypomethylation correlated with the absence of 2,4-D, addition of 5-azacytidine (5-azaC), but also with the process of habituation. The habituated line was resistant to the effect of hypomethylation drug 5-azaC and remained highly methylated even after the addition of 5-azaC. Also, 5-azaC did not change the developmental pattern in the habituated line, indicating the existence of separate mechanisms by which 2,4-D influences global DNA methylation in comparison to habituation-related global DNA methylation.


Asunto(s)
Cucurbita/genética , Epigénesis Genética/efectos de los fármacos , Ácidos Indolacéticos/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Ácido 2,4-Diclorofenoxiacético/farmacología , Ácido Abscísico/metabolismo , Azacitidina/farmacología , Cucurbita/efectos de los fármacos , Cucurbita/embriología , Citocininas/metabolismo , Metilación de ADN/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Herbicidas/farmacología , Técnicas de Embriogénesis Somática de Plantas
19.
Plant J ; 80(1): 52-68, 2014 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-25041627

RESUMEN

The origin of phytohormones is poorly understood, and their physiological roles in microalgae remain elusive. Genome comparison of photosynthetic autotrophic eukaryotes has revealed that the biosynthetic pathways of abscisic acid (ABA) and cytokinins (CKs) emerged in unicellular algae. While ABA and CK degradation mechanisms emerged broadly in algal lineages, complete vascular plant-type conjugation pathways emerged prior to the rise of Streptophyta. In microalgae, a complete set of proteins from the canonical ABA and CK sensing and signaling pathways is not essential, but individual components are present, suggesting stepwise recruitment of phytohormone signaling components. In the oleaginous eustigmatophyte Nannochloropsis oceanica IMET1, UHPLC-MS/MS detected a wide array of plant hormones, despite a phytohormone profile that is very distinct from that of flowering plants. Time-series transcriptional analysis during nitrogen depletion revealed activation of the ABA biosynthetic pathway and antagonistic transcription of CK biosynthetic genes. Correspondingly, the ABA level increases while the dominant bioactive CK forms decrease. Moreover, exogenous CKs stimulate cell-cycle progression while exogenous ABA acts as both an algal growth repressor and a positive regulator in response to stresses. The presence of such functional flowering plant-like phytohormone signaling systems in Nannochloropsis sp. suggests a much earlier origin of phytohormone biosynthesis and degradation than previously believed, and supports the presence in microalgae of as yet unknown conjugation and sensing/signaling systems that may be exploited for microalgal feedstock development.


Asunto(s)
Nitrógeno/deficiencia , Reguladores del Crecimiento de las Plantas/metabolismo , Transducción de Señal/efectos de los fármacos , Estramenopilos/fisiología , Estrés Fisiológico/efectos de los fármacos , Ácido Abscísico/metabolismo , Compuestos de Bencilo , Evolución Biológica , Vías Biosintéticas/efectos de los fármacos , Ciclo Celular/efectos de los fármacos , Citocininas/metabolismo , Cinetina/metabolismo , Fotosíntesis , Purinas , Estramenopilos/citología , Estramenopilos/genética , Espectrometría de Masas en Tándem
20.
Planta ; 240(1): 55-76, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24677098

RESUMEN

Plant hormones act as chemical messengers in the regulation of myriads of physiological processes that occur in plants. To date, nine groups of plant hormones have been identified and more will probably be discovered. Furthermore, members of each group may participate in the regulation of physiological responses in planta both alone and in concert with members of either the same group or other groups. The ideal way to study biochemical processes involving these signalling molecules is 'hormone profiling', i.e. quantification of not only the hormones themselves, but also their biosynthetic precursors and metabolites in plant tissues. However, this is highly challenging since trace amounts of all of these substances are present in highly complex plant matrices. Here, we review advances, current trends and future perspectives in the analysis of all currently known plant hormones and the associated problems of extracting them from plant tissues and separating them from the numerous potentially interfering compounds.


Asunto(s)
Reguladores del Crecimiento de las Plantas , Plantas/química , Reguladores del Crecimiento de las Plantas/química , Reguladores del Crecimiento de las Plantas/aislamiento & purificación , Transducción de Señal
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA