RESUMEN
Higher-order chromatin structure is critical for regulation of gene expression. In plants, light profoundly affects the morphogenesis of emerging seedlings as well as global gene expression to ensure optimal adaptation to environmental conditions. However, the changes and functional significance of chromatin organization in response to light during seedling development are not well documented. We constructed Hi-C contact maps for the cotyledon, apical hook and hypocotyl of soybean subjected to dark and light conditions. The resulting high-resolution Hi-C contact maps identified chromosome territories, A/B compartments, A/B sub-compartments, TADs (Topologically Associated Domains) and chromatin loops in each organ. We observed increased chromatin compaction under light and we found that domains that switched from B sub-compartments in darkness to A sub-compartments under light contained genes that were activated during photomorphogenesis. At the local scale, we identified a group of TADs constructed by gene clusters consisting of different numbers of Small Auxin-Upregulated RNAs (SAURs), which exhibited strict co-expression in the hook and hypocotyl in response to light stimulation. In the hypocotyl, RNA polymerase II (RNAPII) regulated the transcription of a SAURs cluster under light via TAD condensation. Our results suggest that the 3D genome is involved in the regulation of light-related gene expression in a tissue-specific manner.
Asunto(s)
Cromatina , Regulación de la Expresión Génica de las Plantas , Glycine max , Hipocótilo , Luz , Glycine max/genética , Glycine max/metabolismo , Glycine max/crecimiento & desarrollo , Cromatina/metabolismo , Cromatina/genética , Hipocótilo/genética , Hipocótilo/crecimiento & desarrollo , Hipocótilo/metabolismo , Cotiledón/genética , Cotiledón/crecimiento & desarrollo , Cotiledón/metabolismo , Cotiledón/efectos de la radiación , Plantones/genética , Plantones/crecimiento & desarrollo , Plantones/efectos de la radiaciónRESUMEN
Ultraviolet-B (UV-B) radiation has a wavelength range of 280-315 nm. Plants perceive UV-B as an environmental signal and a potential abiotic stress factor that affects development and acclimation. UV-B regulates photomorphogenesis including hypocotyl elongation inhibition, cotyledon expansion, and flavonoid accumulation, but high intensity UV-B can also harm plants by damaging DNA, triggering accumulation of reactive oxygen species, and impairing photosynthesis. Plants have evolved "sunscreen" flavonoids that accumulate under UV-B stress to prevent or limit damage. The UV-B receptor UV RESISTANCE LOCUS 8 (UVR8) plays a critical role in promoting flavonoid biosynthesis to enhance UV-B stress tolerance. Recent studies have clarified several UVR8-mediated and UVR8-independent pathways that regulate UV-B stress tolerance. Here, we review these additions to our understanding of the molecular pathways involved in UV-B stress tolerance, highlighting the important roles of ELONGATED HYPOCOTYL 5, BRI1-EMS-SUPPRESSOR1, MYB DOMAIN PROTEIN 13, MAP KINASE PHOSPHATASE 1, and ATM- and RAD3-RELATED. We also summarize the known interactions with visible light receptors and the contribution of melatonin to UV-B stress responses. Finally, we update a working model of the UV-B stress tolerance pathway.
Asunto(s)
Aclimatación , Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiología , Arabidopsis/genética , Arabidopsis/efectos de la radiación , Proteínas de Arabidopsis/genética , Cotiledón/genética , Cotiledón/fisiología , Cotiledón/efectos de la radiación , Hipocótilo/genética , Hipocótilo/fisiología , Hipocótilo/efectos de la radiación , Modelos Biológicos , Estrés Fisiológico , Rayos Ultravioleta/efectos adversosRESUMEN
Cotyledon opening is a key morphological change that occurs in seedlings during de-etiolation. Brassinosteroids (BRs) inhibit the opening of cotyledons in darkness while light promotes cotyledon opening. The molecular regulation of the interplay between light and BR to regulate cotyledon opening is not well understood. Here, we show the B-box protein BBX32 negatively regulates light signaling and promotes BR signaling to inhibit cotyledon opening in Arabidopsis (Arabidopsis thaliana). BBX32 is highly expressed in the cotyledons of seedlings during de-etiolation. bbx32 and 35S:BBX32 seedlings exhibit enhanced and reduced cotyledon opening, respectively, in response to both light and brassinazole treatment in dark, suggesting that BBX32 mediates cotyledon opening through both light and BR signaling pathways. BBX32 expression is induced by exogenous BR and is upregulated in bzr1-1D (BRASSINAZOLE RESISTANT1-1D). Our in vitro and in vivo interaction studies suggest that BBX32 physically interacts with BZR1. Further, we found that PHYTOCHROME-INTERACTING FACTOR 3 (PIF3) interacts with BBX32 and promotes BR-mediated cotyledon closure. BBX32, BZR1, and PIF3 regulate the expression of common target genes that modulate the opening and closing of cotyledons. Our work suggests BBX32 integrates light and BR signals to regulate cotyledon opening during de-etiolation.
Asunto(s)
Proteínas de Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Brasinoesteroides/metabolismo , Proteínas Portadoras/genética , Cotiledón/crecimiento & desarrollo , Luz , Transducción de Señal , Arabidopsis/genética , Arabidopsis/efectos de la radiación , Proteínas de Arabidopsis/metabolismo , Proteínas Portadoras/metabolismo , Cotiledón/genética , Cotiledón/efectos de la radiaciónRESUMEN
Light is one of the most important environmental factors, serving as the energy source of photosynthesis and a cue for plant developmental programs, called photomorphogenesis. Here, we provide a standardized operation to measure physiological parameters of photomorphogenesis, including in hypocotyl length, cotyledon size, and anthocyanin content.
Asunto(s)
Antocianinas/metabolismo , Arabidopsis/crecimiento & desarrollo , Cotiledón/anatomía & histología , Hipocótilo/anatomía & histología , Arabidopsis/anatomía & histología , Arabidopsis/química , Arabidopsis/efectos de la radiación , Cotiledón/química , Cotiledón/crecimiento & desarrollo , Cotiledón/efectos de la radiación , Hipocótilo/química , Hipocótilo/crecimiento & desarrollo , Hipocótilo/efectos de la radiación , Luz , Tamaño de los Órganos/efectos de la radiación , FenotipoRESUMEN
Responses of rice seedlings to UV-B radiation (UV-B) were investigated, aiming to establish rice as a model plant for UV-B signalling studies. The growth of japonica rice coleoptiles, grown under red light, was inhibited by brief irradiation with UV-B, but not with blue light. The effective UV-B fluences (10-1 -103 µmol m-2 ) were much lower than those reported in Arabidopsis. The response was much less in indica rice cultivars and its extent varied among Oryza species. We next identified UV-B-specific anthocyanin accumulation in the first leaf of purple rice and used this visible phenotype to isolate mutants. Some isolated mutants were further characterized, and one was found to have a defect in the growth response. Using microarrays, we identified a number of genes that are regulated by low-fluence-rate UV-B in japonica coleoptiles. Some up-regulated genes were analysed by real-time PCR for UV-B specificity and the difference between japonica and indica. More than 70% of UV-B-regulated rice genes had no homologs in UV-B-regulated Arabidopsis genes. Many UV-B-regulated rice genes are related to plant hormones and especially to jasmonate biosynthetic and responsive genes in apparent agreement with the growth response. Possible involvement of two rice homologs of UVR8, a UV-B photoreceptor, is discussed.
Asunto(s)
Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Mutación/genética , Transducción de Señal/genética , Transducción de Señal/efectos de la radiación , Rayos Ultravioleta , Antocianinas/metabolismo , Arabidopsis/genética , Arabidopsis/efectos de la radiación , Cotiledón/crecimiento & desarrollo , Cotiledón/efectos de la radiación , Oryza/genética , Oryza/efectos de la radiación , Plantones/metabolismo , Regulación hacia Arriba/genética , Regulación hacia Arriba/efectos de la radiaciónRESUMEN
After germination, plants determine their morphogenesis, such as hypocotyl elongation and cotyledon opening, by responding to various wavelengths of light (photomorphogenesis). Cryptochrome is a blue-light photoreceptor that controls de-etiolation, stomatal opening and closing, flowering time, and shade avoidance. Successful incorporation of these phenotypes as indicators into a chemical screening system results in faster selection of candidate compounds. Here, we describe phenotypic screening for the blue-light response of Arabidopsis thaliana seedling and the resulting process that clarifies that the compound obtained in the screening is an inhibitor of cryptochromes.
Asunto(s)
Arabidopsis/metabolismo , Criptocromos/antagonistas & inhibidores , Bibliotecas de Moléculas Pequeñas/análisis , Arabidopsis/crecimiento & desarrollo , Arabidopsis/efectos de la radiación , Sistema Libre de Células , Cotiledón/anatomía & histología , Cotiledón/efectos de los fármacos , Cotiledón/efectos de la radiación , Criptocromos/metabolismo , Criptocromos/efectos de la radiación , Medios de Cultivo , Hipocótilo/anatomía & histología , Hipocótilo/efectos de los fármacos , Hipocótilo/efectos de la radiación , Procesamiento de Imagen Asistido por Computador , Luz , Fenotipo , Biosíntesis de Proteínas/efectos de los fármacos , Biosíntesis de Proteínas/efectos de la radiación , Proteínas Recombinantes/biosíntesis , Plantones/efectos de los fármacos , Plantones/efectos de la radiación , Bibliotecas de Moléculas Pequeñas/farmacologíaRESUMEN
Exposure of dark-grown (etiolated) seedlings to light induces the heterotrophic-to-photoautotrophic transition (de-etiolation) processes, including the formation of photosynthetic machinery in the chloroplast and cotyledon expansion. Phytochrome is a red (R)/far-red (FR) light photoreceptor that is involved in the various aspects of de-etiolation. However, how phytochrome regulates metabolic dynamics in response to light stimulus has remained largely unknown. In this study, to elucidate the involvement of phytochrome in the metabolic response during de-etiolation, we performed widely targeted metabolomics in Arabidopsis (Arabidopsis thaliana) wild-type and phytochrome A and B double mutant seedlings de-etiolated under R or FR light. The results revealed that phytochrome had strong impacts on the primary and secondary metabolism during the first 24 h of de-etiolation. Among those metabolites, sugar levels decreased during de-etiolation in a phytochrome-dependent manner. At the same time, phytochrome upregulated processes requiring sugars. Triacylglycerols are stored in the oil bodies as a source of sugars in Arabidopsis seedlings. Sugars are provided from triacylglycerols through fatty acid ß-oxidation and the glyoxylate cycle in glyoxysomes. We examined if and how phytochrome regulates sugar production from oil bodies. Irradiation of the etiolated seedlings with R and FR light dramatically accelerated oil body mobilization in a phytochrome-dependent manner. Glyoxylate cycle-deficient mutants not only failed to mobilize oil bodies but also failed to develop thylakoid membranes and expand cotyledon cells upon exposure to light. Hence, phytochrome plays a key role in the regulation of metabolism during de-etiolation.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Etiolado/genética , Fitocromo A/metabolismo , Fitocromo B/metabolismo , Plantones/metabolismo , Azúcares/metabolismo , Arabidopsis/enzimología , Arabidopsis/genética , Arabidopsis/efectos de la radiación , Proteínas de Arabidopsis/genética , Cromatografía Líquida de Alta Presión , Cotiledón/metabolismo , Cotiledón/efectos de la radiación , Cotiledón/ultraestructura , Etiolado/efectos de la radiación , Glioxilatos/metabolismo , Glioxisomas/metabolismo , Glioxisomas/efectos de la radiación , Luz , Gotas Lipídicas/metabolismo , Gotas Lipídicas/efectos de la radiación , Metaboloma/efectos de la radiación , Metabolómica , Microscopía Electrónica de Transmisión , Mutación , Fitocromo A/genética , Fitocromo B/genética , Plantones/efectos de la radiación , Tilacoides/metabolismo , Tilacoides/ultraestructura , Triglicéridos/metabolismoRESUMEN
Glycine betaine (GB), an osmolyte, is produced in chloroplasts by the action of betaine aldehyde dehydrogenase (BADH) on its precursor betaine aldehyde. The present work highlights the significance of nitric oxide (NO) in GB homeostasis as a long-distance salt (120 mM NaCl) stress-elicited response. In light-grown seedling cotyledons, both the activity and transcript levels of BADH are much higher than in dark-grown seedlings irrespective of salt stress. Significantly high accumulation of GB in dark-grown seedling cotyledons indicates its preferential mobilization from cotyledons to other plant parts in light-grown seedlings. NO donor application (diethylenetriamine) maintains high BADH activity in light, although in dark it is brought down marginally. BADH levels are maintained high in light than in dark in respective treatments. Reversal of the effect of NO donor on age-dependent GB content, BADH activity, and transcript levels by NO scavenger (diethyldithiocarbamate) further demonstrates the impact of NO on GB homeostasis in light- and dark-grown seedlings in an age-dependent manner, major modulation being observed in 4-d-old seedlings. The present work, thus, provides new information on co-regulation of GB homeostasis by NO and light. It also puts forward new information of GB-NO crosstalk in maneuvering salt stress sensing as a long-distance response in seedlings.
Asunto(s)
Betaína Aldehído Deshidrogenasa/metabolismo , Betaína/metabolismo , Cotiledón/metabolismo , Helianthus/efectos de la radiación , Luz , Óxido Nítrico/metabolismo , Plantones/metabolismo , Cotiledón/efectos de la radiación , Helianthus/metabolismo , Plantones/efectos de la radiaciónRESUMEN
Light elicits different growth responses in different organs of plants. These organ-specific responses are prominently displayed during de-etiolation. While major light-responsive components and early signaling pathways in this process have been identified, this information has yet to explain how organ-specific light responses are achieved. Here, we report that members of the TEOSINTE BRANCHED1, CYCLOIDEA, and PCF (TCP) transcription factor family participate in photomorphogenesis and facilitate light-induced cotyledon opening in Arabidopsis (Arabidopsis thaliana). Chromatin immunoprecipitation sequencing and RNA sequencing analyses indicated that TCP4 targets a number of SMALL AUXIN UPREGULATED RNA (SAUR) genes that have previously been shown to exhibit organ-specific, light-responsive expression. We demonstrate that TCP4-like transcription factors, which are predominantly expressed in the cotyledons of both light- and dark-grown seedlings, activate SAUR16 and SAUR50 expression in response to light. Light regulates the binding of TCP4 to the promoters of SAUR14, SAUR16, and SAUR50 through PHYTOCHROME-INTERACTING FACTORs (PIFs). PIF3, which accumulates in etiolated seedlings and its levels rapidly decline upon light exposure, also binds to the SAUR16 and SAUR50 promoters, while suppressing the binding of TCP4 to these promoters in the dark. Our study reveals that the interplay between light-responsive factors PIFs and the developmental regulator TCP4 determines the cotyledon-specific light regulation of SAUR16 and SAUR50, which contributes to cotyledon closure and opening before and after de-etiolation.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Fitocromo/metabolismo , Factores de Transcripción/metabolismo , Arabidopsis/fisiología , Arabidopsis/efectos de la radiación , Proteínas de Arabidopsis/genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Cotiledón/genética , Cotiledón/fisiología , Cotiledón/efectos de la radiación , Etiolado/efectos de la radiación , Ácidos Indolacéticos/metabolismo , Luz , Plantones/genética , Factores de Transcripción/genética , Activación Transcripcional , Regulación hacia ArribaRESUMEN
KEY MESSAGE: Inclusion of carbon nanoparticles in growth medium accelerates timing to flower by down-regulating phytochrome B in a CONSTANS-independent but photoperiod-dependent manner in Arabidopsis thaliana. Despite the recognized importance of nanoparticles in plant development over the last decade, the effect of carbon nanoparticles (CNPs) on plant processes such as photomorphogenesis and flowering time control is poorly understood. We explored the uptake, accumulation and effect of CNPs on seedling development and flowering time control in Arabidopsis thaliana (At). CNPs uptake was demonstrated using Raman spectroscopy and light microscopy that affected At seedling growth and flowering time in a dose-dependent manner. The highest accumulation of CNPs was observed in leaves followed by stem and root tissues. CNPs treatment enhanced seed germination, showed elongated hypocotyl, larger cotyledon area and increased chlorophyll content in At seedlings. CNPs treatment induced early flowering in both long-day and short-day growth conditions indicating a photoperiod-dependent effect. CNPs-treated seedlings showed a drastic reduction in the relative abundance of phytochrome B (PHYB) transcript. Further, we analyzed the transcript abundance of at least one major component involved in various pathways that regulate flowering such as (1) photoperiod, (2) gibberellic acid (GA), (3) vernalization and (4) autonomous. An up-regulation of transcript levels of PHYTOCHROME INTERACTING FACTOR 4 (PIF4), GIGANTEA (GI), REPRESSOR OF GIBBERELLIC ACID 1 (RGA1) and LEAFY (LFY) were observed, however, there were no changes in the transcript levels of CONSTANS (CO), VERNALIZATION 1 (VRN1) and FLOWERING CONTROL LOCUS A (FCA). Despite the up-regulation of RGA1, we conclude that the earlier flowering is most likely GA-independent. Here, we demonstrated that the early flowering in CNPs-treated seedlings was PHYB and photoperiod-dependent.
Asunto(s)
Arabidopsis/fisiología , Carbono/metabolismo , Regulación de la Expresión Génica de las Plantas , Nanopartículas/metabolismo , Fotoperiodo , Fitocromo B/metabolismo , Arabidopsis/genética , Arabidopsis/efectos de la radiación , Cotiledón/genética , Cotiledón/fisiología , Cotiledón/efectos de la radiación , Flores/genética , Flores/fisiología , Flores/efectos de la radiación , Giberelinas/metabolismo , Luz , Reguladores del Crecimiento de las Plantas/metabolismo , Hojas de la Planta/genética , Hojas de la Planta/fisiología , Hojas de la Planta/efectos de la radiación , Plantones/genética , Plantones/fisiología , Plantones/efectos de la radiaciónRESUMEN
KEY MESSAGE: DSBs differently affect endoreduplication and organ size in radish cotyledons and hypocotyls in different light conditions, suggesting that DSBs-mediated endoreduplication varies based on different developmental and environmental cues. Endoreduplication induced by DNA double strand breaks (DSBs) in Arabidopsis thaliana roots and cultured cells has been reported in recent years. In this study, we investigated whether DSBs-mediated endoreduplication also occurs in other tissues, such as cotyledons and hypocotyls of radish (Raphanus sativus var. longipinnatus) plants. To induce DSBs, UV irradiation and Zeocin treatment were applied to in vitro-cultured radish seedlings, and ploidy distribution of the treated tissues was analyzed by flow cytometry. Consequently, frequencies of the higher ploidy (8C) cells and cycle values in the cotyledon tissues increased with increasing doses of UV irradiation and concentrations of Zeocin, irrespective of light conditions. UV-stimulated endoreduplication was also observed in four Brassica species. In hypocotyls, UV treatments decreased the frequencies of higher ploidy (32C) cells and cycle values in dark-grown seedlings, whereas Zeocin treatments increased the frequencies of higher ploidy (16C and 32C) cells and cycle values in light- and dark-grown seedlings. Among the treatments, organ sizes did not simply correlate with cycle values. The effects of treatments on endoreduplication and organ size differed based on organ and light conditions, indicating that DSBs-mediated endoreduplication may involve a multifaceted response to different developmental and environmental cues.
Asunto(s)
Roturas del ADN de Doble Cadena , Endorreduplicación/genética , Raphanus/genética , Cotiledón/genética , Cotiledón/fisiología , Cotiledón/efectos de la radiación , Endorreduplicación/efectos de la radiación , Hipocótilo/genética , Hipocótilo/fisiología , Hipocótilo/efectos de la radiación , Raíces de Plantas/genética , Raíces de Plantas/fisiología , Raíces de Plantas/efectos de la radiación , Ploidias , Raphanus/fisiología , Raphanus/efectos de la radiación , Plantones/genética , Plantones/fisiología , Plantones/efectos de la radiaciónRESUMEN
In this study, the effects of UV-B radiation on the isoflavones accumulation, physiological and nutritional quality, water status, and characteristics of proteins in germinated soybeans were investigated. The results showed that isoflavones content in soybeans increased with appropriate intensity and time of UV-B radiation and decreased with excessive treatment. Fresh weight, length, free amino acids, reducing sugar contents and bulk water (T23) in germinated soybeans decreased with increasing radiation time, indicating that UV-B inhibited the growth and nutrients metabolism of soybean during germination. Cell damage was detected in germinated soybeans with excessive UV-B radiation, as shown by the black spots in cotyledons and the increased intercellular water determined by LF-NMR. Germination resulted in an increase in random coil structures, while UV-B radiation induced no obvious changes in FT-IR spectrum and protein conformation of soybeans. Both UV-B radiation and germination caused the increase in soluble proteins, especially in 1.0-75.0â¯kDa fraction.
Asunto(s)
Glycine max/efectos de la radiación , Isoflavonas/metabolismo , Semillas/crecimiento & desarrollo , Carbohidratos , Cotiledón/química , Cotiledón/crecimiento & desarrollo , Cotiledón/metabolismo , Cotiledón/efectos de la radiación , Germinación , Isoflavonas/química , Valor Nutritivo , Semillas/química , Semillas/metabolismo , Semillas/efectos de la radiación , Glycine max/química , Glycine max/crecimiento & desarrollo , Glycine max/metabolismo , Espectroscopía Infrarroja por Transformada de Fourier , Rayos UltravioletaAsunto(s)
Fototransducción/fisiología , Proteínas de Plantas/metabolismo , Plantones/metabolismo , Triglicéridos/metabolismo , Cotiledón/crecimiento & desarrollo , Cotiledón/metabolismo , Cotiledón/efectos de la radiación , Oscuridad , Endospermo/crecimiento & desarrollo , Endospermo/metabolismo , Endospermo/efectos de la radiación , Hipocótilo/crecimiento & desarrollo , Hipocótilo/metabolismo , Hipocótilo/efectos de la radiación , Luz , Fototransducción/efectos de la radiación , Plantas/clasificación , Plantas/metabolismo , Plantas/efectos de la radiación , Plantones/crecimiento & desarrollo , Plantones/efectos de la radiaciónRESUMEN
Arabidopsis (Arabidopsis thaliana) VASCULAR-RELATED NAC-DOMAIN1 (VND1) to VND7 encode a group of NAC domain transcription factors that function as master regulators of xylem vessel element differentiation. These transcription factors activate the transcription of genes required for secondary cell wall formation and programmed cell death, key events in xylem vessel element differentiation. Because constitutive overexpression of VND6 and VND7 induces ectopic xylem vessel element differentiation, functional studies of VND proteins have largely focused on these two proteins. Here, we report the roles of VND1, VND2, and VND3 in xylem vessel formation in cotyledons. Using our newly established in vitro system in which excised Arabidopsis cotyledons are stimulated to undergo xylem cell differentiation by cytokinin, auxin, and brassinosteroid treatment, we found that ectopic xylem vessel element differentiation required VND1, VND2, and VND3 but not VND6 or VND7. The importance of VND1, VND2, and VND3 also was indicated in vivo; in the vnd1 vnd2 vnd3 seedlings, xylem vessel element differentiation of secondary veins in cotyledons was inhibited under dark conditions. Furthermore, the light responsiveness of VND gene expression was disturbed in the vnd1 vnd2 vnd3 mutant, and vnd1 vnd2 vnd3 failed to recover lateral root development in response to the change of light conditions. These findings suggest that VND1 to VND3 have specific molecular functions, possibly linking light conditions to xylem vessel formation, during seedling development.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crecimiento & desarrollo , Arabidopsis/metabolismo , Cotiledón/crecimiento & desarrollo , Factores de Transcripción/metabolismo , Xilema/metabolismo , Arabidopsis/citología , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Análisis por Conglomerados , Cotiledón/citología , Cotiledón/efectos de la radiación , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Genes de Plantas , Luz , Modelos Biológicos , Mutación/genética , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/efectos de la radiación , ARN Mensajero/genética , ARN Mensajero/metabolismo , Xilema/citología , Xilema/genética , Xilema/efectos de la radiaciónRESUMEN
BACKGROUND: Cowpeas stored under high temperature and humidity develop the hard-to-cook defect (HTC). This defect greatly increases cooking times and energy costs. To better understand the mechanisms involved in the HTC defect development, the effects of gamma-irradiation on cotyledon cellular structure and pectin solubility in two cowpea cultivars with different susceptibility to HTC defect were investigated. RESULTS: Gamma-irradiation decreased cotyledon cell wall thickness, increased cell size, and intercellular spaces in both cowpea cultivars and reduced cooking time of the less HTC susceptible cultivar. However, it did not reverse the HTC defect in the susceptible cultivar. Gamma-irradiation also increased the levels of cold water- and hot water-soluble pectin. The irradiation effects were thus mainly due to hydrolysis of pectin fractions in the cell walls. However, chelator-soluble pectin (CSP) solubility was not affected. CONCLUSION: As the cell wall changes brought about by gamma-irradiation were associated with pectin solubilisation, this supports the phytate-phytase-pectin theory as a major cause of the HTC defect. However, the non-reversal of the defect in HTC susceptible cowpeas and the absence of an effect on CSP indicate that other mechanisms are involved in HTC defect development in cowpeas, possibly the formation of alkali-soluble, ester bonded pectins. © 2017 Society of Chemical Industry.
Asunto(s)
Cotiledón/química , Manipulación de Alimentos/métodos , Pectinas/química , Extractos Vegetales/química , Vigna/embriología , Vigna/efectos de la radiación , Fraccionamiento Químico , Culinaria , Cotiledón/efectos de la radiación , Manipulación de Alimentos/instrumentación , Rayos gamma , Calor , Pectinas/aislamiento & purificación , Extractos Vegetales/aislamiento & purificación , Solubilidad , Vigna/químicaRESUMEN
We investigated the response to increasing intensity of red (R) and far-R (FR) light and to a decrease in R:FR ratio in Pinus sylvestris L. (Scots pine) seedling. The results showed that FR high-irradiance response for hypocotyl elongation may be present in Scots pine and that this response is enhanced by increasing light intensity. However, both hypocotyl inhibition and pigment accumulation were more strongly affected by the R light compared with FR light. This is in contrast to previous reports in Arabidopsis thaliana (L.) Heynh. In the angiosperm, A. thaliana R light shows an overall milder effect on inhibition of hypocotyl elongation and on pigment biosynthesis compared with FR suggesting conifers and angiosperms respond very differently to the different light regimes. Scots pine shade avoidance syndrome with longer hypocotyls, shorter cotyledons and lower chlorophyll content in response to shade conditions resembles the response observed in A. thaliana. However, anthocyanin accumulation increased with shade in Scots pine, which again differs from what is known in angiosperms. Overall, the response of seedling development and physiology to R and FR light in Scots pine indicates that the regulatory mechanism for light response may differ between gymnosperms and angiosperms.
Asunto(s)
Luz , Pinus sylvestris/fisiología , Pinus sylvestris/efectos de la radiación , Plantones/fisiología , Plantones/efectos de la radiación , Análisis de Varianza , Cotiledón/crecimiento & desarrollo , Cotiledón/efectos de la radiación , Hipocótilo/crecimiento & desarrollo , Hipocótilo/efectos de la radiación , Pigmentos Biológicos/metabolismo , Pinus sylvestris/crecimiento & desarrollo , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/efectos de la radiación , Plantones/crecimiento & desarrolloRESUMEN
Here, we compared the development of dark- and light-grown Chinese fir (Cunninghamia lanceolata) cotyledons, which synthesize chlorophyll in the dark, representing a different phenomenon from angiosperm model plants. We determined that the grana lamellar membranes were well developed in both chloroplasts and etiochloroplasts. The accumulation of thylakoid membrane protein complexes was similar between chloroplasts and etiochloroplasts. Measurement of chlorophyll fluorescence parameters indicated that photosystem II (PSII) had low photosynthetic activities, whereas the photosystem I (PSI)-driven cyclic electron flow (CEF) rate exceeded the rate of PSII-mediated photon harvesting in etiochloroplasts. Analysis of the protein contents in etiochloroplasts indicated that the light-harvesting complex II remained mostly in its monomeric conformation. The ferredoxin NADP+ oxidoreductase and NADH dehydrogenase-like complexes were relatively abundantly expressed in etiochloroplasts for Chinese fir. Our transcriptome analysis contributes a global expression database for Chinese fir cotyledons, providing background information on the regulatory mechanisms of different genes involved in the development of dark- and light-grown cotyledons. In conclusion, we provide a novel description of the early developmental status of the light-dependent and light-independent photosynthetic apparatuses in gymnosperms.
Asunto(s)
Cunninghamia/fisiología , Cunninghamia/efectos de la radiación , Luz , Fotosíntesis/efectos de la radiación , Clorofila/metabolismo , Cotiledón/metabolismo , Cotiledón/efectos de la radiación , Cunninghamia/genética , Oscuridad , Transporte de Electrón/efectos de la radiación , Fluorescencia , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Complejos Multiproteicos/metabolismo , Fosforilación/efectos de la radiación , Complejo de Proteína del Fotosistema I/metabolismo , Complejo de Proteína del Fotosistema II/metabolismo , Plastidios/metabolismo , Plastidios/ultraestructura , Plantones/crecimiento & desarrollo , Plantones/efectos de la radiaciónRESUMEN
The impact of short-term UV-B treatment on the content of individual flavonoids and photosynthetic pigments in cotyledons and the growth of common buckwheat (Fagopyrum esculentum Moench) seedlings was investigated. Seeds of four common buckwheat cultivars were germinated in darkness over a period of 4 days and acclimatized for 2 days under a 16/8 h light/dark photoperiod at 24/18 °C day/night, and exposure to 100-120 µmol â m-2 â s-1 of photosynthetically active radiation (PAR). Seedlings were divided into three batches, including two batches subjected to different doses of UV-B (5 W â m-2 and 10 W â m-2, one hour per day) for 5 days, and a control group exposed to PAR only. Exposure to UV-B increased anthocyanin levels in the cotyledons of all examined cultivars, it inhibited hypocotyl elongation, but did not affect the content of photosynthetic pigments. Flavone concentrations increased in cv. Red Corolla and Kora, remained constant in cv. Panda and decreased in cv. Hruszowska. Exposure to UV-B decreased rutin levels in cv. Hruszowska, but not in the remaining cultivars. Cultivars Hruszowska, Panda and Kora appeared to be less resistant to UV-B than Red Corolla. Higher resistance to UV-B radiation in Red Corolla can probably be attributed to its higher content of anthocyanins and rutin in comparison with the remaining cultivars.
Asunto(s)
Antocianinas/efectos de la radiación , Carotenoides/efectos de la radiación , Cotiledón/efectos de la radiación , Fagopyrum/efectos de la radiación , Flavonas/efectos de la radiación , Flavonoles/efectos de la radiación , Plantones/efectos de la radiación , Rayos Ultravioleta , Antocianinas/metabolismo , Carotenoides/metabolismo , Clorofila/metabolismo , Clorofila/efectos de la radiación , Cotiledón/metabolismo , Fagopyrum/crecimiento & desarrollo , Fagopyrum/metabolismo , Flavonas/metabolismo , Flavonoides/metabolismo , Flavonoides/efectos de la radiación , Flavonoles/metabolismo , Hipocótilo/crecimiento & desarrollo , Hipocótilo/efectos de la radiación , Fenoles/metabolismo , Fenoles/efectos de la radiación , Rutina/metabolismo , Rutina/efectos de la radiación , Plantones/crecimiento & desarrolloRESUMEN
KEY MESSAGE: Enhancement of endoreduplication in dark-grown hypocotyl is a common feature in dicotyledonous polysomatic plants, and TIBA-mediated inhibition of the endoreduplication is partially due to abnormal actin organization. Many higher plant species use endoreduplication during cell differentiation. However, the mechanisms underlying this process have remained elusive. In this study, we examined endoreduplication in hypocotyls and cotyledons in response to light in some dicotyledonous plant species. Enhancement of endoreduplication was found in the dark-grown hypocotyls of all the polysomatic species analyzed across five different families, indicating that this process is a common feature in dicotyledonous plants having polysomatic tissues. Conversely, endoreduplication was enhanced in the light-grown cotyledons in four of the five species analyzed. We also analyzed the effect of a polar auxin transport inhibitor, 2,3,5-triiodobenzoic acid (TIBA) on endoreduplication in hypocotyl and cotyledon tissues of radish (Raphanus sativus L. var. longipinnatus Bailey). TIBA was found to inhibit and promote endoreduplication in hypocotyls and cotyledons, respectively, suggesting that the endoreduplication mechanism differs in these organs. To gain insight into the effect of TIBA, radish and spinach (Spinacia oleracea L.) seedlings were treated with a vesicle-trafficking inhibitor, brefeldin A, and an actin polymerization inhibitor, cytochalasin D. Both of the inhibitors partially inhibited endoreduplication of the dark-grown hypocotyl tissues, suggesting that the prominent inhibition of endoreduplication by TIBA might be attributed to its multifaceted role.