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1.
An Acad Bras Cienc ; 91(3): e20180439, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31531531

RESUMO

The orchid seed banks of Atlantic Forest may be considered a key strategy for the conservation of species threatened with extinction by indiscriminate collection or habitat destruction. The aim of this study was to evaluate the seed viability, to choose the best culture medium for the asymbiotic germination and evaluate germination, after storage for different periods and temperatures for the Brazilian native orchids: Gomesa praetexta (Rchb.f.) M.W.Chase & N.H.Williams, Gomesa forbesii (Hook.) M.W.Chase & N.H.Williams, Gomesa recurva R.Br. and Grandiphyllum divaricatum (Lindl.) Docha Neto. Knudson C (KC), Murashige & Skoog (MS), half-strength MS (1/2 MS macro- and micro-nutrients) and Woody Plant Medium (WPM) culture media were tested for germination. The WPM culture medium was the best for asymbiotic germination of all species evaluated, with high germination percentages and improved seedling development. Seeds of G. divaricatum, G. praetexta, G. recurva and G. forbesii indicated orthodox behavior, with high viability rates after 12 months of storage, being recommended the storage temperature of -80°C for the first three species and -20°C for G. forbesii. The protocol developed in the present study was efficient for seed bank storage, in vitro germination and seedling production of G. divaricatum and G. praetexta, contributing to conservation strategies of these species.


Assuntos
Técnicas de Cultura/métodos , Germinação/fisiologia , Orchidaceae/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento , Aclimatação , Brasil , Meios de Cultura , Espécies em Perigo de Extinção , Florestas , Orchidaceae/classificação , Banco de Sementes
2.
An Acad Bras Cienc ; 91(3): e20180924, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31531534

RESUMO

The authors of the 19th century had demonstrated the viviparity of the species Rhizophora mangle L. with the formation of propagules in the form of spears devoid a radicle, adapted self-planting in the soil of the mangrove or to leave floating in vertical during the high tide. With low tide the propagules self-planting or remain prostrate on the soil but later become upright later. When the seedlings are unearthed, those who are self-planting are straight from end to end; those that stood erect later show a curvature at the base in the form of J (J-shaped). Authors of the last 30 years have questioned the self-planting and accurately demonstrate how the prostrate propagules rise from the ground. It has been verified that the propagule is stem from end to end and does not present radicle, that is, under the plumale there is the hypocotyls without a root. All roots are adventitious, agreeing with 19th century researchers, not lateral roots as researchers of the present century have claimed. Propagules that return to the beach in Porto Seguro (BA) probably of another flowering period show an extra growth of the lower part, but this growth remains a stem rather than a root, demonstrating that there is no root, as 19th century researchers claimed.


Assuntos
Rhizophoraceae/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Avicennia , Brasil , Germinação , Rhizophoraceae/citologia , Rhizophoraceae/fisiologia , Plântula/citologia , Plântula/fisiologia , Solo , Áreas Alagadas
3.
Microbiol Res ; 229: 126331, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31521945

RESUMO

The uses of halotolerant bacteria isolated from naturally saline habitats have the potential to be useful crop protection agents for plants in stressful conditions. These beneficial microbes generate several plant growth regulators and bioactive molecules, which enhance plant protection from adversities, such as plant pathogens, salts and metals stresses. In this study, 15 halotolerant bacterial strains endowed with important antimicrobial activities were isolated from Sfax solar saltern (Tunisia). All of these strains were characterized by biochemical and molecular tools aiming to investigate their in-vitro and in-vivo antifungal potentialities, plant growth promotion capabilities and metal tolerance abilities under saline stress condition. The 16S rRNA gene sequencing showed that the isolated strains were affiliated to different phylum and three species were described for the first time as plant growth promoting strains (Idiomarina zobelli FMH6v, Nesterenkonia halotolerans FMH10 and Halomonas janggokensis FMH54). The tested strains exhibited several potentialities: to tolerate high salt and heavy metal concentrations, to produce biosurfactants, exopolysaccharides and extracellular hydrolytic enzymes, to form biofilms and to liberate plant promoting substances. Eight strains were able to protect tomatoes fruits from the proliferation of the fungal disease caused by Botrytis cinerea and six strains improved plant vigor indexes. Principal component analysis showed an important correlation between in-vitro and in-vivo potentialities and two strains Bacillus velezensis FMH2 and Bacillus subtilis subsp. spizizenii FMH45 were statistically considered as the most effective strains in protecting plants from fungal pathogens attack and promoting the growth of tomatoes seedlings under saline and multi heavy-metals stress conditions.


Assuntos
Bactérias/isolamento & purificação , Fenômenos Fisiológicos Bacterianos , Lycopersicon esculentum/microbiologia , Água do Mar/microbiologia , Cloreto de Sódio/metabolismo , Bactérias/classificação , Bactérias/genética , Botrytis/fisiologia , Lycopersicon esculentum/crescimento & desenvolvimento , Doenças das Plantas/microbiologia , Salinidade , Água do Mar/química , Plântula/crescimento & desenvolvimento , Plântula/microbiologia , Cloreto de Sódio/análise , Estresse Fisiológico , Tunísia
4.
J Agric Food Chem ; 67(42): 11607-11615, 2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31560536

RESUMO

ζ-carotene desaturase (ZDS) is a key enzyme in carotenoid biosynthesis and plays an important role in plant photosynthesis. We characterized an albino leaf-color mutant obtained from ethyl methanesulfonate treatment: albino and seedling lethality 1 (ale1). The material contains a chloroplast thylakoid defect where photosynthetic pigments declined and reactive oxygen species accumulated resulting in ale1 death within 3 weeks. Positional cloning and sequencing revealed that there was a single base substitution in ALE1, which encoded a ZDS involved in carotenoid biosynthesis. RNAi and complementation tests confirmed the identity of ALE1. Subcellular localization showed that the ALE1 protein is localized in the chloroplast. Expression analysis indicated that the genes involved in chlorophyll and carotenoid biosynthesis were downregulated. We conclude that ALE1 plays an important role in chloroplast and plant growth in rice.


Assuntos
Cloroplastos/enzimologia , Oryza/crescimento & desenvolvimento , Oxirredutases/genética , Proteínas de Plantas/genética , Clorofila/metabolismo , Cloroplastos/genética , Regulação da Expressão Gênica de Plantas , Oryza/enzimologia , Oryza/genética , Oxirredutases/metabolismo , Fotossíntese , Proteínas de Plantas/metabolismo , Interferência de RNA , Plântula/enzimologia , Plântula/genética , Plântula/crescimento & desenvolvimento
5.
J Agric Food Chem ; 67(39): 10813-10822, 2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31490069

RESUMO

Traditional seed pretreatment methods cause secondary pollution for the application of various chemicals. This study investigated the effect of dielectric barrier discharge (DBD) cold plasma on seedling growth. Effects of plasma-activated tap water (PATW) and plasma-activated seeds (PAS) were compared for germination rates, seedling height, dry weight, and chlorophyll content. Results show that compared with controls these growth parameters were all increased by more than 50%. The yields and contributions of hydrogen peroxide, nitrate, nitrite, and ammonium were quantified. Hydrogen peroxide and nitrate have an important role in seedling growth. By etching, the seed epidermis free radicals can reduce the apparent contact angle and increase the water absorption of the seeds. In addition to the low cost of PATW and PAS compared with commercial fertilizers, DBD does not involve any chemical addition. Thus, both PATW and PAS can be an alternative for improvement of agricultural production.


Assuntos
Produção Agrícola/métodos , Ervilhas/efeitos dos fármacos , Gases em Plasma/farmacologia , Sementes/crescimento & desenvolvimento , Compostos de Amônio/metabolismo , Clorofila/metabolismo , Produção Agrícola/instrumentação , Germinação/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Nitratos/metabolismo , Ervilhas/química , Ervilhas/crescimento & desenvolvimento , Ervilhas/metabolismo , Gases em Plasma/química , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Sementes/química , Sementes/efeitos dos fármacos , Sementes/metabolismo , Água/química
6.
Chemosphere ; 235: 1066-1072, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561296

RESUMO

This study was conducted to explore the effects of priming of seven-year-old aged seeds with different concentrations of silver nanoparticles (AgNPs) on growth of broad bean (Vicia faba L.). Seeds were primed with different concentrations of AgNPs for 6 h before growing in the plastic trays. Different growth parameters like growth attributes, photosynthetic pigments, carbohydrates, antioxidant enzymes and chloroplast ultrastructure were estimated after 14 days of germination. Priming with AgNPs affected the root and shoot growth attributes as compared with control depending upon concentrations of AgNPs. In all treatments, photosynthetic pigments increased significantly above control levels, but total soluble sugars decreased in 10 and 50 ppm AgNPs and slightly increased in 100 ppm AgNPs as compared with control. Starch accumulation was apparent in all treated seedlings above that of control levels. Mesophyll cells of all treated seedlings were altered with electron dense particles than control. Priming with AgNPs affected the chloroplast structure which appeared in the form of less stacking of Greene, formation of protrusions and extensions, irregular shape of chloroplasts as compared with spindle shaped regular chloroplasts of control. In all treatments, total phenols were slightly affected as compared with control. The antioxidant enzyme activities in seedlings varied with the dose and type of antioxidants. Overall, AgNPs adversely affected the chloroplast ultrastructure, but increased growth of seedlings and starch accumulation. Further studies are required to explore the effects of AgNPs on the long-term on crop productivity of aged seeds.


Assuntos
Cloroplastos/efeitos dos fármacos , Nanopartículas Metálicas/química , Plântula/ultraestrutura , Prata/química , Antioxidantes/farmacologia , Cloroplastos/ultraestrutura , Germinação/efeitos dos fármacos , Fotossíntese , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Sementes/efeitos dos fármacos , Prata/farmacologia , Amido/metabolismo , Vicia faba/crescimento & desenvolvimento , Vicia faba/ultraestrutura
7.
Ying Yong Sheng Tai Xue Bao ; 30(9): 2955-2963, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31529870

RESUMO

Light is a key factor affecting seed germination and seedling growth. In this study, seed germination and seedling growth of Cunninghamia lanceolata and Schima superba were compared under controlled conditions with five light treatments (100%, 60%, 40%, 15% and 5% of full sunlight). The results showed that light intensity significantly impacted seed germination and seedling growth of both species. With decreasing light intensity, the germination rate and germination index of C. lanceolata increased, while those of S. superba showed a trend which increased first and then decreased, with the maximum at 40% light intensity. The seedling survival rate of both species was 0 under full sunlight, while significantly decreased with decreasing light intensity from 60% to 5%. Root length, basal stem diameter and height showed a consistent trend with the change of light availability in both species. Root length significantly decreased, basal stem diameter and height increased first and then decreased with decreasing light intensity, with the minimum at 5% light intensity. With decreasing light intensity, root biomass, stem biomass, leaf biomass and total biomass of C. lanceolata seedlings declined, while high biomass accumulation of S. superba seedlings were observed in 15%-60% light intensities, and lowest at 5% light intensity. Biomass accumulation in each organ of S. superba seedlings was greater than that of C. lanceolata seedlings under the same light intensity. High stem biomass and leaf biomass, low root biomass and root to shoot ratio were a phenotypic response to low light intensity in C. lanceolata and S. superba seedlings grown under poor light condition. The growth of C. lanceolata is better under relatively high light intensity than S. superba. Whereas S. superba is moderately shade-tolerant at the seedling stage, thus is more suitable for planting under closed canopy.


Assuntos
Cunninghamia/fisiologia , Germinação/fisiologia , Plântula/crescimento & desenvolvimento , Theaceae , Sementes
8.
J Agric Food Chem ; 67(35): 9772-9781, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31398019

RESUMO

This study aims to investigate the response profiles of vitamin E and carotenoids on transcription and metabolic levels of sweet corn seedlings under temperature stress. The treated temperatures were set as 10 °C (low temperature, LT), 25 °C (control, CK), and 40 °C (high temperature, HT) for sweet corn seedlings. The gene expression profiles of vitamin E and carotenoids biosynthesis pathways were analyzed by real time quantitative polymerase chain reaction (RT-qPCR), and the composition profiles were analyzed by high performance liquid chromatography (HPLC). Results showed that vitamin E gradually accumulated in response to LT stress but was limited by HT stress. The increase of carotenoids was suppressed by LT stress whereas HT stress promoted it. The existing results elaborated the interactive and competitive relationships of vitamin E and carotenoids in sweet corn seedlings to respond to extreme temperature stress at transcriptional and metabolic levels. The present study would improve sweet corn temperature resilience with integrative knowledge in the future.


Assuntos
Carotenoides/metabolismo , Vitamina E/metabolismo , Zea mays/metabolismo , Carotenoides/análise , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plântula/química , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Estresse Fisiológico , Temperatura Ambiente , Vitamina E/análise , Zea mays/química , Zea mays/genética , Zea mays/crescimento & desenvolvimento
9.
J Agric Food Chem ; 67(31): 8452-8458, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31294967

RESUMO

Insights into the environmental fates of nitrated polycyclic aromatic hydrocarbons (NPAHs) in edible vegetables are of great significance for better evaluating human exposure to NPAHs through the dietary pathway. In this work, a fluorescence quenching method using graphene quantum dots as a fluorescent probe was first applied for the in vivo determination of 9-nitroanthracene (9-NAnt) and 1-nitropyrene (1-NPyr) adsorbed on the leaf surfaces of living lettuce (Lactuca sativa L.) seedlings. Moreover, the photolysis kinetics and mechanisms of the two adsorbed NPAHs were discussed. The photodegradation kinetics followed the pseudo-first-order equation, and the photodegradation half-life of 1-NPyr (7.4 ± 0.2 h) was greater than that of 9-NAnt (2.3 ± 0.1 h). Anthraquinone and pyrenediones were identified to be the main photolytic products of 9-NAnt and 1-NPyr, respectively. Intramolecular rearrangement was the most reasonable mechanism for the NPAH photolysis. The photolysis-driven degradation exhibited a key role in scavenging NPAHs from the vegetable leaf, indicating the reduction of NPAH transportation in the food chain.


Assuntos
Alface/química , Nitratos/química , Folhas de Planta/química , Hidrocarbonetos Policíclicos Aromáticos/química , Poluentes Atmosféricos/química , Cinética , Alface/crescimento & desenvolvimento , Alface/efeitos da radiação , Fotólise/efeitos da radiação , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/efeitos da radiação , Plântula/química , Plântula/crescimento & desenvolvimento , Plântula/efeitos da radiação
10.
Photochem Photobiol Sci ; 18(8): 1945-1962, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31305802

RESUMO

Exposure to ambient UV-B radiation may prime protective responses towards various stressors in plants, though information about interactive effects of UV-B and gamma radiation is scarce. Here, we aimed to test whether UV-B exposure could prime acclimatisation mechanisms contributing to tolerance to low-moderate gamma radiation levels in Scots pine seedlings, and concurrently whether simultaneous UV-B and gamma exposure may have an additive adverse effect on seedlings that had previously not encountered either of these stressors. Responses to simultaneous UV-B (0.35 W m-2) and gamma radiation (10.2-125 mGy h-1) for 6 days with or without UV-B pre-exposure (0.35 W m-2, 4 days) were studied across various levels of organisation, as compared to effects of either radiation type. In contrast to UV-B, and regardless of UV-B presence, gamma radiation at ≥42.9 mGy h-1 caused increased formation of reactive oxygen species and reduced shoot length, and reduced root length at 125 mGy h-1. In all experiments there was a gamma dose rate-dependent increase in DNA damage at ≥10.8 mGy h-1, generally with additional UV-B-induced damage. Gamma-induced growth inhibition and gamma- and UV-B-induced DNA damage were still visible 44 days post-irradiation, even at 20.7 mGy h-1, probably due to genomic instability, but this was reversed after 8 months. In conclusion, there was no evidence of a protective effect of UV-B on gamma-induced growth inhibition and DNA damage in Scots pine, and no additive adverse effect of gamma and UV-B radiation on growth in spite of the additional UV-B-induced DNA damage.


Assuntos
Raios gama , Pinus sylvestris/crescimento & desenvolvimento , Pinus sylvestris/efeitos da radiação , Plântula/crescimento & desenvolvimento , Plântula/efeitos da radiação , Raios Ultravioleta
11.
Zhongguo Zhong Yao Za Zhi ; 44(10): 2032-2037, 2019 May.
Artigo em Chinês | MEDLINE | ID: mdl-31355557

RESUMO

In order to accelerate the breeding of the excellent seedlings of Polygonatum cyrtonema,tissue culture system of P. cyrtonema was established through the comprehensive regulation of key factors( leaf age,leaf location,basic media and plant growth regulators) and cytological basis of callus formation and differentiation was analyzed through paraffin section. The results showed that the 30-day-old leaf base explanton medium MS+6-BA 1. 50 mg·L~(-1)+2,4-D 0. 20 mg·L~(-1) had the highest induction rate( 80. 00%). The callus was initiated from cells on leaf base epidermis and near cortex,formed by the differentiation of middle vascular bundle cells. The optimal medium for adventitious bud differentiation was MS+ 6-BA 4. 00 mg·L~(-1)+ 2,4-D 0. 20 mg·L~(-1) with the differentiation rate of90. 33%,and the average number of buds was 5. 16. The adventitious buds had two origin types: exogenous and endogenous origin,formed by callus proximal cells and callus internal meristemoid. The adventitious bud proliferation medium was screened by orthogonal design,which determined the optimum combination was MS+ 6-BA 2. 00 mg·L~(-1)+NAA 0. 10 mg·L~(-1) and MS+ 6-BA 2. 00 mg·L~(-1)+NAA 0. 20 mg·L~(-1). The tubers with three leaves were cut and inoculated in the medium 1/2 MS+IBA 2. 00 mg·L~(-1),showing the highest rooting rate of 94. 00%. The rooting seedlings transplanted into the peat-vermiculite( 1 ∶ 1) matrix grew healthy and the survival rate was over 85. 00%. This research provided a novel solution for large-scale cultivation of P. cyrtonema seedling.


Assuntos
Meios de Cultura , Polygonatum/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Técnicas de Cultura de Tecidos , Reguladores de Crescimento de Planta , Folhas de Planta/citologia , Regeneração
12.
Plant Mol Biol ; 101(1-2): 183-202, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31286324

RESUMO

KEY MESSAGE: Isoforms of 2-OGDH E1 subunit are not functionally redundant in plant growth and development of A. thaliana. The tricarboxylic acid cycle enzyme 2-oxoglutarate dehydrogenase (2-OGDH) converts 2-oxoglutarate (2-OG) to succinyl-CoA concomitant with the reduction of NAD+. 2-OGDH has an essential role in plant metabolism, being both a limiting step during mitochondrial respiration as well as a key player in carbon-nitrogen interactions. In Arabidopsis thaliana two genes encode for E1 subunit of 2-OGDH but the physiological roles of each isoform remain unknown. Thus, in the present study we isolated Arabidopsis T-DNA insertion knockout mutant lines for each of the genes encoding the E1 subunit of 2-OGDH enzyme. All mutant plants exhibited substantial reduction in both respiration and CO2 assimilation rates. Furthermore, mutant lines exhibited reduced levels of chlorophylls and nitrate, increased levels of sucrose, malate and fumarate and minor changes in total protein and starch levels in leaves. Despite the similar metabolic phenotypes for the two E1 isoforms the reduction in the expression of each gene culminated in different responses in terms of plant growth and seed production indicating distinct roles for each isoform. Collectively, our results demonstrated the importance of the E1 subunit of 2-OGDH in both autotrophic and heterotrophic tissues and suggest that the two E1 isoforms are not functionally redundant in terms of plant growth in A. thaliana.


Assuntos
Arabidopsis/enzimologia , Carbono/metabolismo , Complexo Cetoglutarato Desidrogenase/metabolismo , Nitrogênio/metabolismo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Dióxido de Carbono/metabolismo , Clorofila/metabolismo , Complexo Cetoglutarato Desidrogenase/genética , Mitocôndrias/enzimologia , Mutagênese Insercional , Nitratos/metabolismo , Fenótipo , Filogenia , Folhas de Planta/enzimologia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Isoformas de Proteínas , Subunidades Proteicas , Plântula/enzimologia , Plântula/genética , Plântula/crescimento & desenvolvimento , Sementes/enzimologia , Sementes/genética , Sementes/crescimento & desenvolvimento
13.
Chemosphere ; 233: 920-935, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31340420

RESUMO

The current study aimed to investigate the impacts of different concentrations of GO/PANI nanocomposites (25, 50 and 100 mg L-1), in comparison with GO and PANI, on seed germination behaviors, morpho-physiological and biochemical traits in intact (mucilaginous) and demucilaged seeds, and young seedlings of the medicinal plant Salvia mirzayanii. Upon exposure to GO, seed germination was delayed and reduced, and growth attributes (root and shoot length, shoot fresh weight, and total chlorophyll content) declined, all of which could be attributed to the reductions in water uptake and oxidative stress particularly in demucilaged seeds. A hormetic dose-dependent response was observed for the growth traits in both intact and demucilaged seedlings upon exposure to GO/PANI concentrations, i.e. low-concentration stimulation and high-concentration repression. Elevated levels of H2O2 in shoot tissue of the seedlings exposed to GO and high concentration of GO/PANI, in comparison with those exposed to low levels of GO/PANI and control, were linked with the activities of the antioxidant enzymes SOD, CAT, POD, and total phenolics. Overall, the results showed high toxicity of GO on germination and early growth of S. mirzayani that was more evident in demucilaged seedlings, whereas GO/PANI stimulated germination, and the effects on seedling growth were stimulatory or inhibitory depending on the application dose and presence of mucilage. Furthermore, the capacity of GO/PANI nanocomposites to improve germination and cause a regular porosity pattern in roots accompanied by improved water uptake and early establishment of S. mirzayanii propose potential implications of GO/PANI nanocomposites for seeds/plants in drought-prone ecosystems.


Assuntos
Compostos de Anilina/toxicidade , Antioxidantes/farmacologia , Germinação/efeitos dos fármacos , Grafite/toxicidade , Salvia/metabolismo , Plântula/crescimento & desenvolvimento , Sementes/efeitos dos fármacos , Catalase/metabolismo , Clorofila , Peróxido de Hidrogênio/farmacologia , Nanocompostos , Estresse Oxidativo/efeitos dos fármacos , Mucilagem Vegetal/metabolismo , Superóxido Dismutase/metabolismo , Água
14.
Environ Sci Pollut Res Int ; 26(22): 22835-22845, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31177416

RESUMO

Soil compaction is a major environmental problem that affects plant growth and development. In this study, to further our understanding of its negative effects on plant growth, we investigated the effects of soil compaction on the growth, mineral absorption, and activities of key respiratory enzymes in soybean seedlings. We found that moderate-level soil compaction increased the activities of pyruvate kinase and phosphofructokinase in soybean seedling roots, enhancing the accumulation of P, K, Mg, Ca, and other elements. These accumulated elements, particularly Ca, increased the number of fibrous upper roots, but reduced root length and inhibited plant growth. High-level soil compaction inhibited the accumulation of P, K, Mg, Mn, Fe, Cu, and Zn and increased the accumulation of Ca via decreasing the activities of isocitrate dehydrogenase and cytochrome c oxidase. These effects led to a decreased root cell size, blurred root cell boundaries, and the inhibition of plant growth. Taken together, our results provide a new insight into the mechanisms by which soil compaction inhibits plant growth.


Assuntos
Plântula/crescimento & desenvolvimento , Solo/química , Soja/crescimento & desenvolvimento , Minerais , Nutrientes , Desenvolvimento Vegetal , Raízes de Plantas/fisiologia
15.
Planta ; 250(2): 657-665, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31147828

RESUMO

MAIN CONCLUSION: The grapevine VvßVPE promoter is specifically expressed in the seed. The - 1306~- 1045 bp core region restricts expression in other tissues and organs. Vacuolar processing enzyme (VPE) is a cysteine proteinase regulating vacuolar protein maturation and executing programmed cell death (PCD) in plants. Vitis vinifera (Vv)ßVPE is a ß-type VPE showing seed-specific expression that processes seed proteins during ovule development. However, the regulation of the seed-specific gene expression is far from understood. In this study, we characterize VvßVPE promoter (pVvßVPE) from 12 seeded and seedless grape genotypes. 94.56% of the pVvßVPE coding sequence is consistent. Two ßVPE promoters were constructed and transformed into Arabidopsis thaliana via ß-glucuronidase (GUS) fused expression vectors, using cv. Pinot Noir and cv. Thompson as seed and seedless candidates. GUS staining in different tissues and organs revealed that VvßVPE expresses specifically in the embryo, including the cotyledon, hypocotyl and suspensor, but not in the leaf, stem, root or flowers of the seedling. Using promoter deletion analysis, we created four incomplete VvßVPE promoters and found each pVvßVPE deletion could drive GUS gene to express in seeds. Interestingly, seed specificity disappeared when the promoter missed the core - 1306~- 1045 bp region. All deletion promoters presenting various quantified GUS activities indicate that the region - 1704~- 1306 bp inhibits, and the region - 705~- 861 bp promotes gene expression of VvßVPE. Our results demonstrate that pVvßVPE is a seed-specific promoter in both seeded and seedless grapes. Moreover, the core region of pVvßVPE (- 1306~- 1045 bp) is the key one responsible for seed-specific expression.


Assuntos
Cisteína Endopeptidases/genética , Regiões Promotoras Genéticas/genética , Sementes/genética , Vitis/genética , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Clonagem Molecular , Regulação da Expressão Gênica de Plantas , Genes Reporter , Especificidade de Órgãos , Óvulo Vegetal/genética , Óvulo Vegetal/crescimento & desenvolvimento , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Plântula/genética , Plântula/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento , Vitis/crescimento & desenvolvimento
16.
Pol J Microbiol ; 68(2): 281-284, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31250597

RESUMO

Changes in the structural diversity of bacterial communities in soybean rhizospheres play important roles in plant growth and crop productivity. However, there are only a few studies on different soybean growth stages. Here, we investigated the changes in the bacterial community of soybean rhizosphere soil at two stages using Illumina high-throughput sequencing. The results showed that the bacterial abundance and diversity in the seeding stage were higher than those in the mature stage and that the diversity changed significantly. Actinobacteria, Acidobacteria, and Proteobacteria were the dominant bacteria in the soybean rhizosphere soil. Additionally, changes in Actinobacteria and Proteobacteria abundances showed opposite trends.Changes in the structural diversity of bacterial communities in soybean rhizospheres play important roles in plant growth and crop productivity. However, there are only a few studies on different soybean growth stages. Here, we investigated the changes in the bacterial community of soybean rhizosphere soil at two stages using Illumina high-throughput sequencing. The results showed that the bacterial abundance and diversity in the seeding stage were higher than those in the mature stage and that the diversity changed significantly. Actinobacteria, Acidobacteria, and Proteobacteria were the dominant bacteria in the soybean rhizosphere soil. Additionally, changes in Actinobacteria and Proteobacteria abundances showed opposite trends.


Assuntos
Bactérias/classificação , Bactérias/isolamento & purificação , Biota , Rizosfera , Plântula/microbiologia , Microbiologia do Solo , Soja/microbiologia , Bactérias/genética , Biologia Computacional , Sequenciamento de Nucleotídeos em Larga Escala , Metagenômica , Plântula/crescimento & desenvolvimento , Soja/crescimento & desenvolvimento
17.
Plant Physiol Biochem ; 141: 291-299, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31202193

RESUMO

Silicon (Si) is reported to improve salt stress tolerance of cereals, but little is known about the effects of Si on flows and partitioning of sodium (Na+), chloride (Cl-), and essential mineral ions at the tissue and cellular level. Wheat (Triticum aestivum L.) was exposed to 200 mM NaCl for 30 d in hydroponics, with or without 2 mM Si. X-ray microanalysis coupled with scanning electron microscopy (SEM) was used to quantify the cell-specific ion profiles across root and leaf cells, paralleled by measurements of wheat growth and physiological responses. Under salt stress, higher Na+ and Cl- concentrations were detected in root epidermal, cortical and stelar cells, eventually increasing their concentrations in different leaf cells, being highest in the epidermal cells and lowest in the vascular bundle cells. The potassium (K+) and magnesium (Mg2+) profiles were generally opposite to those of Na+ and Cl-. NaCl-dependent deregulation of essential nutrient homeostasis and excessive toxic ions accumulation in leaves was correlated with enhanced electrolyte leakage index (ELI), decreased chlorophyll contents, photosynthesis and other physiological parameters, and ultimately hampered plant growth. Conversely, Si addition improved the growth and physiological performance of salinized wheat by reducing Na+ and Cl- concentration in root epidermal and cortical cells, and it improved root uptake and storage of K+ and Mg2+ ions and their loading into xylem for distribution to shoots. These results suggest that Si-mediated inhibition of Na+ uptake, maintained nutrient homeostasis and improved physiological parameters to contribute to wheat growth improvement under salt stress.


Assuntos
Tolerância ao Sal , Sais/química , Silício/química , Triticum/crescimento & desenvolvimento , Biomassa , Cloretos/química , Clorofila/química , Produtos Agrícolas/crescimento & desenvolvimento , Microanálise por Sonda Eletrônica , Genótipo , Homeostase , Hidroponia , Íons , Microscopia Eletrônica de Varredura , Minerais , Fotossíntese , Folhas de Planta/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Potássio/química , Salinidade , Plântula/crescimento & desenvolvimento , Sódio/química , Água/química
18.
Ecotoxicol Environ Saf ; 181: 49-59, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31170649

RESUMO

N-acetylcysteine (N-Acetyl L-cysteine, NAC) is a thiol compound derived from the addition of the acetyl group to cysteine amino acid. NAC has been used as an antioxidant, free radical scavenger, and chelating agent for reducing the deleterious effects on plants of biotic and abiotic environmental stresses. It can also relieve heavy metal (HM) toxicity, although its alleviating mechanism remains unknown. In this study, we compared HM-stressed (Cu, Hg, Cd and Pb, 100 µM each) wheat seedlings without NAC treatment and in combination with NAC (1 mM). In comparison to HMs alone, NAC treatment in combination with HMs (Cu, Cd, Hg and Pb, respectively) stimulated root growth (1.1-, 1.5-, 10.5- and 1.9-fold), and significantly increased fresh (1.3-, 1.5-, 4.3- and 1.4-fold) and dry (1.2-, 1.5-, 2.5- and 1.2-fold) mass. Combination treatment also led to significant reductions in HM concentrations (1.3-, 1.4-, 4- and 1.1-fold, respectively). GSH (1.1 - 1.8-fold), TBARS (1.4 - 2.7-fold) and H2O2 (1.6 - 1.8-fold) contents in treatment with HMs alone were significantly mitigated by the NAC combination. Some of the antioxidant enzyme activities increased or reduced by some HM treatments alone were stimulated by a combination of NAC with HMs, or remained unchanged or changed only insignificantly, supported by the phenolic pool of the plant. Ferulic, p-comaric and syringic acids were the major phenolic acids (PAs) in the roots in free, ester, glycoside and ester-bound forms, and their concentrations were increased by HM treatments alone, in comparison to the control seedlings, while PAs concentrations were relatively reduced by NAC in combination with HMs. These results indicate that NAC can alleviate HM toxicity and improve the growth of HM-stressed wheat seedlings by coordinated induction of the phenolic pool and the antioxidant defence system.


Assuntos
Acetilcisteína/farmacologia , Antioxidantes/farmacologia , Metais Pesados/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Poluentes do Solo/toxicidade , Triticum/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Hidroxibenzoatos/metabolismo , Plântula/efeitos dos fármacos , Plântula/enzimologia , Plântula/crescimento & desenvolvimento , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Triticum/enzimologia , Triticum/crescimento & desenvolvimento
19.
Microbiol Res ; 223-225: 33-43, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31178049

RESUMO

Mangroves, dominating tropical intertidal zones and estuaries, are among the most salt tolerant plants, and propagate through reproductive units called propagules. Similarly to plant seeds, propagules may harbor beneficial bacteria. Our hypothesis was that mangroves, being able to grow into seawater, should harbor bacteria able to interact with the host and to exert positive effects under salt stress, which could be exploited to improve crop production. Therefore, we isolated bacterial endophytes from mangrove propagules with the aim to test whether these bacteria have a beneficial potential on their natural host and on different crops such as barley and rice, cultivated under salt stress. The 172 bacterial isolates obtained were screened for plant growth promotion (PGP) activities in vitro, and the 12 most promising isolates were tested on barley under non-axenic conditions and salt stress. Gordonia terrae KMP456-M40 was the best performing isolate, increasing ear weight by 65%. Based on the in vivo PGP activity and the root colonization ability, investigated by fluorescence in situ hybridization and confocal microscopy, three strains were additionally tested on mangrove propagule germination and on rice growth. The most effective strain was again G. terrae KMP456-M40, which enhanced the root length of mangrove seedlings and the biomass of salt-stressed rice under axenic conditions up to 65% and 62%, respectively. We demonstrated that propagules, the reproductive units of mangroves, host beneficial bacteria that enhance the potential of mangrove seedlings establishment and confer salt tolerance to cereal crops.


Assuntos
Produtos Agrícolas , Grão Comestível/crescimento & desenvolvimento , Endófitos/fisiologia , Desenvolvimento Vegetal , Estresse Salino , Bactérias/classificação , Bactérias/isolamento & purificação , Biomassa , Endófitos/classificação , Endófitos/crescimento & desenvolvimento , Endófitos/isolamento & purificação , Genótipo , Germinação , Hordeum/crescimento & desenvolvimento , Hordeum/microbiologia , Hibridização in Situ Fluorescente , Oryza/microbiologia , Pressão Osmótica , Raízes de Plantas/microbiologia , Salinidade , Tolerância ao Sal , Plantas Tolerantes a Sal/microbiologia , Arábia Saudita , Água do Mar , Plântula/crescimento & desenvolvimento , Plântula/microbiologia , Sementes/crescimento & desenvolvimento , Sementes/microbiologia , Microbiologia do Solo , Áreas Alagadas
20.
Plant Sci ; 285: 214-223, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203886

RESUMO

Main Conclusion Root gravitropism of primary roots is assisted by curvature of the hypocotyl base. Root gravitropism is typically described as the sequence of signal perception, signal processing, and response that causes differential elongation and the establishment of a new gravitropic set-point angle. We describe two components of the graviresponse of Brassica seedlings that comprise a primary curvature of the root tip and a later onset but stronger curvature that occurs at the base of the hypocotyl. This second curvature is preceded by straightening of the tip region but leads to the completion of the alignment of the root axis. Curvature in both regions require a minimum displacement of 20 deg. The rate of tip curvature is a function of root length. After horizontal reorientation, tip curvature of five mm long roots curved twice as fast as 10 mm long roots (33.6 ±â€¯3.3 vs. 14.3 ±â€¯1.5 deg hr-1). The onset of curvature at the hypocotyl base is correlated with root length, but the rate of this curvature is independent of seedling length. Decapping of roots prevented tip curvature but the curvature at base of hypocotyl was unaffected. Endodermal cells at the root shoot junction show numerous, large and sedimenting amyloplasts, which likely serve as gravity sensors (statoliths). The amyloplasts at the hypocotyl were 3-4 µm in diameter, similar in size to those in the root cap, and twice the size of starch grains in the cortical layers of hypocotyl or elsewhere in the root. These data indicate that the root shoot reorientation of young seedlings is not limited to the root tip but includes more than one gravitropically responsive region.


Assuntos
Brassica rapa/crescimento & desenvolvimento , Gravitropismo , Hipocótilo/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Brassica rapa/fisiologia , Hipocótilo/fisiologia , Coifa/crescimento & desenvolvimento , Coifa/fisiologia
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