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  • Open access
  • 30 Reads
Plant Signaling Pathways in Response to Multiple Stressors

Plants need the dimensions for rapid and accurate identification of exterior stimuli inside their environment for endurance. Upon acquaintance with biotic or abiotic stressors, plants can stimulate long-distance, electrical, chemical or hydraulic signals or trigger systemic stress responses. The overlying occurrence and rapidity of the signals upon plant exposure to numerous stressors varieties it stimulating to classify the signal introducing plant systemic stress/defence responses. Moreover, it is understood that systemic plant responses are not conveyed by a single pathway, but slightly by a combination of signals enabling the transmission of information on the dominant stressor(s) and its strength. In this paper, we précis the mode of action of long-distance, electrical, chemical and hydraulic signals, deliberate their importance in information transmission to biotic and abiotic stressors, and propose future research directions.

  • Open access
  • 18 Reads
Galactolipids as Potential Biomarkers for Early Diagnosis of Esca Complex Disease in Asymptomatic Grapevine

Esca complex disease seriously affects vine yield and longevity. Because of the time delay between wood infection by fungi and symptom expression, current disease diagnosis relies on destructive sampling of the wood, usually a difficult and costly procedure. The goal of this study was to identify metabolites that could be used as biomarkers for developing a noninvasive biochemical method for early diagnosis of esca complex disease. A Q-Exactive Hybrid Quadrupole-Orbitrap high resolution/accurate mass spectrometric-based platform was used to assess the lipidomic profile of healthy leaves from healthy vines, asymptomatic leaves from wood-affected vines, and symptomatic leaves with two different degrees of severity. Biochemicals were separated on ultrahigh performance liquid chromatography and gas chromatography. A total of 208 compounds were detected, including fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, prenol lipids, sterol lipids, hormones, carotenoids, chlorophylls, and metabolites of the carnitine and choline metabolisms. Biomarkers of symptom emergence were identified by different classification methods, including volcano plots, hierarchical clustering, principal component analysis, pathway mapping and rich factor analysis. Of all the biochemical classes, the galactolipid class (glycerophospholipids) was the only variable that explained differences among experimental groups. Indeed, the levels of 13 galactolipids increased in leaves of asymptomatic vines, and progressively decreased with the appearance of foliar symptoms. A positive correlation between the level of leaf necrosis and levels of galactolipids was found, suggesting a role for galactolipids in the etiopathogenesis of esca complex disease. Such information could be used for identification of esca-affected vines without the need to rely upon symptomatic descriptors.

  • Open access
  • 8 Reads
Novel Copper Nanoparticles for the Control of Tomato Foliar and Fruit Diseases

Grey mould caused by Botrytis cinerea and Late Blight caused by Phytophthora infestans, are the most important foliar and fruit diseases of tomato. Applications of fungicides are the main control measures of these diseases. However, development of resistance to single-site inhibitors by both pathogens necessitates research for the development of alternative products. Initially, 4 novel Nano-copper (Cu-NPs) formulations were evaluated in vitro. The 2 most efficient formulations (CN_S4_X1 and CC_S4_X2) from the in vitro assay were further evaluated for their efficacy against B. cinerea and P. infestans on tomato seedling plants (cv. Belladona) at the 4th true leaf growth stage under controlled environmental conditions. To evaluate the protective and curative activity of the Cu-NPs tested, spray treatments were conducted 24, 48 and 96 h before (protective treatments) or after (curative treatments) the inoculation of the plants. For both pathogens, disease severity on plants treated curatively was higher than in plants treated preventively. Applications of the two Cu-NPs against B. cinerea 24 h prior the inoculation led to lower disease severity with means of 1.5 and 1.3, respectively, compared to 48h and 96h before or after inoculation. Disease severity was significantly higher on plants treated with the commercial copper products. Similarly, the 2 Cu-NPs tested were found to be highly effective against P. infestans as provided lower disease severity at 24h and 48h pre-/post-inoculation. The results of this study are expected to contribute in the optimization of tomato diseases control and reduce the yield losses caused, using a new generation of biocides.

This research has been co‐financed by the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship, and Innovation, under the call RESEARCH – CREATE – INNOVATE (project code: T1EDK- 01492).

  • Open access
  • 33 Reads
Effects of Processing Methods on Phytochemical Compositions of Selected Plants Materials with Animal Nutrition Potentials

Plants contain significant amounts of bioactive compounds which have potential benefits to livestock and humans. This study evaluated the phytochemicals of some plant materials that have potential animal nutrition values. In this study, fresh samples (6 samples per each) of four leaves: Siam weed (Chromolaena odorata L.), African basil (Ocimum gratissimum L.), waterleaf (Talinum triangulare Jacq. Willd), and Mexican sunflower (Tithonia diversifolia Hemsl. A. Gray) were air-dried (between 27 and 31 oC), oven-dried (at 65 oC) or freeze-dried (at -80 oC). The leaves were milled in a 1.0 mm sieve and the phytochemical contents of each leaf sample (in triplicates) were quantified. Phytochemicals quantified were flavonoids, tannins, beta carotene, and xanthophylls for each of the leaves. Data were subjected to Analysis of Variance and significant means separated using Duncan Multiple Range Test. Flavonoids, tannins, and xanthophylls were found to be the highest (P < 0.05) in most air-dried leaf samples compared to oven-dried and freeze-dried ones. Flavonoids, tannins, beta carotene, and xanthophylls in the leaves showed that all leaf samples appear to have good potentials to be used as natural feed additives such as egg yolk colourants in laying chicken feeds. In-vivo studies using birds were recommended.

  • Open access
  • 19 Reads
Effects of Waterlogging on Growth and Development of Bread Wheat Genotypes

Bread wheat (Triticum aestivum L.) is widely cultivated worldwide. Annually 10-15 million ha of this crop are affected by flooding of cultivated land leading to large production losses (20 to 50%). Intensive and unpredictable rainfall episodes are expected to increase due to global warming. More adapted varieties may be useful to cope with climatic changes. The aim of this work is to evaluate the effects of waterlogging on growth and development of four bread wheat genotypes from different origins, including one Portuguese landrace, and one advanced line obtained through National Wheat Breeding Program (INIAV, Elvas, Portugal). Plants were grown in climatized growth chambers. Waterlogging was imposed at tillering stage, and maintained for two weeks. Phenological observations through Zadoks scale, as well as senescence evaluation through SPAD measurements in 2nd leaf, were performed during stress imposition. Main shoot height was unaltered in two genotypes, which also presented relative chlorophyll content (SPAD) reductions (29-80%) in relation to control plants. The other two genotypes increased main shoot height 62% and 144% and showed stable SPAD values, reflecting a higher photosynthetic ability. The genotypes capacity to contain progressive senescence induced by waterlogging will be assessed through the ratio between green/senescent biomass (dry weight) after stress, and after 7 and 14 days of recovery.

  • Open access
  • 22 Reads
Biochemical Analysis of Banana Plants in Interaction Between Endophytic Bacteria Kocuria rhizophila and the Fungal Pathogen Fusarium oxysporum f.sp. cubense Tropical Race
(Foc TR4)

Fusarium wilt, caused by Fusarium oxysporum f.sp. cubense Tropical Race 4 (Foc TR4) is one of the most severe banana diseases in the world. In this study, the endophytic bacteria Kocuria rhizophila which had been isolated previously from banana leaves was used. Endophytic bacteria are proven to increase plant growth and can trigger plant systemic resistance (ISR). The biochemical response of bananas inoculated with K. rhizophila is unknown, so this study aimed to explore the activity of peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL) enzymes, and analyze the total phenolic content of banana plants inoculated with K. rhizophila before being infected with Foc TR4. Banana plants treated with K. rhizophila showed increased PO enzyme activity increased and reached its highest activity 72 hours after inoculation in shoots (0,1640±0,0335

  • Open access
  • 23 Reads
Plant Disease Symptomatology: Cucumber Green Mottle Mosaic Virus (CGMMV)-Infected Cucumber Plants Exposed to Fluctuating Extreme Temperatures

Greenhouse grown cucumber plants inspected during and following extreme variations in environmental temperatures showed new characteristics of Cucumber green mottle mosaic virus (CGMMV) disease manifestations. An increasing occurrence of high temperature-induced CGMMV disease recovery has been associated with a new phenotype identified at early stages of a reemerging disease. Symptoms of bright yellow islands (BYIs) conspicuous amid a dark green surrounding (DGS) tissue were detected in up to 10% of the symptomatic plants in commercial net-houses that showed 50-60% recovery following an extreme temperature wave. The high CGMMV titer in the BYIs and the low virus titer in the associated DGS tissue were infectious in biological assays. A controlled study of CGMMV-infected cucumber plants subjected to an abrupt temperature raise, from 25°C to 32°C, allowed monitoring symptomatology of early stages of disease recovery and reemergence. Our study revealed an early and late BYI stages that were associated with a consecutive up- and down-regulation of jasmonic acid (JA) signaling and a corresponding increase in JA inhibitory pathways concomitant with disease progression. Interestingly, the cucumber plant response to the late disease stage was associated with increasing activity of the phenylpropanoid pathway in the DGS tissues apparently indicating high activity of plant resistance pathways towards the disease including levels of reactive oxygen species and specific interference with tobamoviruses. Disclosing the cucumber molecular pathways, engaged at the early CGMMV disease initiation stages, have allowed pinpointing the preferable treatments in order to confine the CGMMV disease and prevent viral systemic infection.

  • Open access
  • 21 Reads
The Phenotypic Reactivity of Passiflora incarnata L. on Various Content of Mineral Salts and Regulators During Micropropagation and Acclimatization

Passiflora incarnata is ornamental and medicinal plant that contains a valuable active chemical derivatives of apigenin and luteolin. Conventional cultivation of this plant in Poland is a very problematic, caused by the low percentage of seed germination, viability of seedlings, and plant diseases which can seriously reduce the productivity of P. incarnata. An alternative and promising way to solve these problems may be used the technique of micropropagation, which may have applied for the plant multiplication under controlled conditions and have offered the production of healthy, pathogen-free and true-to-type plants.

The aim of this study was to detrmine 1) the influence of IAA (0.1-1.0 mg L-1), and IBA (0.1-1.0 mg L-1) on brasilian seed germination, and 2) the influence of various concetrations of mineral salts in Murashige and Shoog (MS), Gamborg (B-5), Shenk-Hildebrandt (SH) and Phytamax media on growth, development and condition of plant in vitro, 3) induction of adventitious shoots using nodal fragments under influence of BAP (0.1-1.0 mg L-1), TDZ (0.1-1.0 mg L-1), KIN (0.1-1.0 mg L-1) with IAA (0.1 mg L-1). Results showed that 1) MS medium with IAA (1.0 mg L-1) has been most efective in induction of seed germination (60%); 2) Gamborg (B-5) medium has been more favorable for plant growth and development, and 3) SH with BAP (1.0 mg L-1) and TDZ (0.1 L-1) with IAA induced more adventitious buds and new regenerated plantlets. After rooting, 100% obtrained plants have been actimatizared to ex vitro conditions and have been observed in greenhaouse.

  • Open access
  • 64 Reads
Germination Performance of Different Sorghum Cultivars under Saline Conditions

Sorghum bicolor (L.) Moench is among the most-produced cereal in the world. Although this species grows well in different environments, the accumulation of salts in the soil generality limits its development. Hence, this study aimed to evaluate the influence of salinity on the germinative aspects of four sorghum cultivars. The experiment was carried out at the Laboratories of Ecophysiology of Plant Production and Seed Analysis, both at the Federal University of Ceará (UFC), located in Fortaleza, Ceará State, Brazil. The experimental design used was completely randomized (CRD), in a 4 x 5 factorial arrangement, with four sorghum cultivars (BRS-373, BRS-380, BRS-658, and BRS-716) and five NaCl concentrations (0, 50, 100, 150 and 200 mM), with four replications. The variables investigated were final germination percentage (FGP), first count germination (FCG), mean germination time (MGT), germination speed index (GSI) and sodium and potassium contents (radicle and aerial part). The findings demonstrated that the salinity levels interfered negatively in the germination performance of all cultivars, showing an expressive reduction, mainly in the highest concentration of NaCl. The lowest germination indices were observed for BRS-373 cultivar, which, although it has shown less sodium accumulation in the root, was enough to cause metabolism delays. On the other hand, the BRS-716 cultivar exhibited the greatest potential for salinity tolerance in the early stages of development, higher germination indices and lower sodium accumulation when compared to potassium in the aerial part.

  • Open access
  • 100 Reads
Differential Tolerance of Cowpea Cultivars to Osmotic Stress in Germinative Phase: A Multivariate Approach

Studies on germination and initial development of plants emerge as a promising approach that might provide relevant information for identifying tolerance to abiotic stresses, such as water deficit. Thus, this study aimed to characterize the behavior of different cultivars of Vigna unguiculata L. Walp. to water deficit, from germination and vigor parameters. The experiment was conducted at the Seed Analysis Laboratory of the Federal University of Ceará, located in Fortaleza, Ceará, Brazil. The experimental design used was completely randomized (CRD), in a 14x4 factorial arrangement, with fourteen cultivars (BRS-Pujante, BRS-Guariba, BRS-Potengi, BR 17-Gurgueia, BRS-Tumucumaque, BRS-Pajeú, BRS-Rouxinol, BRS-Novaera, BRS-Xiquexique, BRS-Milênio, BRS-Acauã, Patativa, BR 3-Tracuateua, and BRS-Aracê) and four levels of osmotic potential (0, -0.1, -0.2 and -0.4 MPa) of the germination solution, with four repetitions. The variables analyzed were final percentage of germination, germination speed index, average germination time, root and aerial part lengths, root dry mass and dry mass of the aerial part and the relationship between them. Data were analyzed through exploratory principal component analysis (PCA) using the R software. The BRS-Milênio, BRS-Acauã and BRS-Aracê cultivars presented difficulties in tolerating the stresses of -0.1 and -0.2 MPa, especially the BRS-Milênio cultivar at the level -0.2 MPa. Whereas BRS-Novaera and BRS-Pajeú cultivars were characterized with possible tolerance at both the -0.1 and -0.2 MPa levels. The study pointed to the BRS-Pujante cultivar as the most sensitive to the -0.4 MPa level. The multivariate technique used allowed for a satisfactory characterization of the treatments adopted.

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