Organs Of Seedlings Research Articles

Fusarium species associated with naturally regenerated Fagus sylvatica seedlings affected by Phytophthora

AbstractFusarium diseases in forests, especially in naturally regenerated seedlings, are poorly recognized. Recently the rapid and severe decline of natural regeneration of European beech caused by Phytophthora spp. has been observed in Poland. The diseased beech seedlings were also co-infected by Fusarium species. The aim of this study was to isolate and identify the role of Fusarium species that may play a role in the decline of beech seedlings in Poland. A total of 487 Fusarium isolates were obtained from 450 symptomatic and asymptomatic beech seedlings: 466 from symptomatic plants and 21 from asymptomatic plants. Based on comparisons for two genes and phylogenetic analysis, all Fusarium strains were separated into 14 phylogenetically distinct species belonging to four Fusarium species complexes (SC), namely the F. incarnatum-equiseti species complex (FIESC), the F. nisikadoi species complex (FNSC), the F. sambucinum species complex (FSSC), and the F. tricinctum species complex (FTSC). Fusarium avenaceum and F. paeoniae were the most frequently isolated species from both above- and below-ground organs of seedlings affected by Phytophthora. In the pathogenicity trials, the most virulent species for beech seedlings were F. avenaceum and F. sporotrichioides. However, Fusarium isolates were significantly less aggressive compared to the P. × cambivora (positive control). Our results demonstrate that beech seedlings were frequently colonized by various Fusarium species. Fusarium species do not play an important role in the reduction of naturally regenerated European beech seedlings due to their low aggressiveness.

The Effects of Lead and Cross-Talk Between Lead and Pea Aphids on Defence Responses of Pea Seedlings.

The main goal of this study was to investigate the effect of lead (Pb) at various concentrations, as an abiotic factor, and the cross-talk between Pb and pea aphid (Acyrthosiphon pisum (Harris)) (Hemiptera: Aphididae), as a biotic factor, on the defence responses of pea seedlings (Pisum sativum L. cv. Cysterski). The analysis of growth parameters for pea seedlings demonstrated that Pb at a low concentration, i.e., 0.025-0.0625 mM Pb(NO3)2, caused a hormesis effect, i.e., stimulation of seedling growth, whereas Pb at higher concentrations, i.e., 0.01-0.325 mM Pb(NO3)2, inhibited growth, which manifested as the inhibition of length and fresh biomass. The differences in the level of the main defence-related phytohormones, such as abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA), and indole-3-acetic acid (IAA)-an auxin stimulating plant cell growth-depended on the dose of Pb, aphid infestation and direct contact of the stress factor with the organ. A high accumulation of soluble sugars in the organs of pea seedlings both at sublethal doses and hormetic doses at early experimental time points was observed. At 0 h and 24 h of the experiment, the hormetic doses of Pb significantly stimulated invertase activities, especially in the roots. Moreover, an increase was observed in the pisatin concentration in pea seedlings growing in the presence of different concentrations of Pb and in the case of cross-talk between Pb and A. pisum in relation to the control. Additionally, a significant induction of the expressions of isoflavone synthase (IFS) and 6α-hydroxymaackiain 3-O-methyltransferase (HMM) genes, which participate in the regulation of the pisatin biosynthesis pathway, in pea seedlings growing under the influence of sublethal 0.5 mM Pb(NO3)2 and hormetic 0.075 mM Pb(NO3)2 doses of Pb was noted. The obtained results showed that the response of P. sativum seedlings depends on the Pb dose applied, direct contact of the stress factor with the organ and the duration of contact.

Non-Structural Carbohydrates Accumulation in Seedlings Improved Flowering Quality of Tree Peony under Forcing Culture Conditions, with Roots Playing a Crucial Role.

(1) Tree peony (Paeonia suffruticosa Andrews) is a woody ornamental plant originating from China, and beloved by people worldwide. Non-structural carbohydrates (NSCs) play a crucial role in regulating the flowering quality of tree peonies in both field and potted conditions. However, the effects of NSCs accumulation and allocation in various organs during the vegetative growth stage on the flowering quality of tree peony under forcing culture remains unclear. (2) Two-year-old grafted seedlings of tree peony cv. 'Luoyanghong' were subjected to orthogonal treatments to investigate the role of NSCs accumulation in plants' developmental process. We measured leaf photosynthetic capacity, NSCs accumulation in the organs of seedlings, observed key ornamental characteristics of flowering quality under forcing culture conditions, and evaluated the qualities of seedlings and flowers using the seedling index (SI) and flowering index (FI), respectively. (3) There was a significant positive correlation between leaf photosynthetic capacity and NSCs accumulation in both the whole plant and roots of potted tree peony. Roots were identified as the primary organs for NSCs accumulation in potted tree peonies. Sufficient NSCs accumulation in the plant, particularly in the roots during the defoliation period, was essential not only for enhancing the seedling quality of potted tree peonies but also for improving the flowering quality under forcing culture conditions. Both the seedling index (SI) and flowering index (FI) exhibited a significant dose-response with increasing root NSCs accumulation at defoliation. The T3 group, which involved slight root pruning (by 25%), combined with a high-concentration rooting agent (750 mg·L-1) and Metarhizium anisopliae (20 million U·mL-1), resulted in the highest photosynthetic capacity, SI, FI and NSCs accumulation status (NSCAR), making it the optimal treatment combination. (4) This finding indicates that increasing NSCs accumulation in the roots of potted tree peonies is a crucial biological foundation for producing high-quality potted flowers under forcing culture conditions, which provide new insights into the importance of NSCs in tree peony flowering and may improve the production technology for high-quality potted tree peony flowers under forcing culture conditions.

Cuticle development and the underlying transcriptome-metabolome associations during early seedling establishment.

The plant cuticle is a complex extracellular lipid barrier that has multiple protective functions. This study investigated cuticle deposition by integrating metabolomics and transcriptomics data gathered from six different maize seedling organs of four genotypes, the inbred lines B73 and Mo17, and their reciprocal hybrids. These datasets captured the developmental transition of the seedling from heterotrophic skotomorphogenic growth to autotrophic photomorphogenic growth, a transition that is highly vulnerable to environmental stresses. Statistical interrogation of these data revealed that the predominant determinant of cuticle composition is seedling organ type, whereas the seedling genotype has a smaller effect on this phenotype. Gene-to-metabolite associations assessed by integrated statistical analyses identified three gene networks associated with the deposition of different elements of the cuticle: cuticular waxes; monomers of lipidized cell wall biopolymers, including cutin and suberin; and both of these elements. These gene networks reveal three metabolic programs that appear to support cuticle deposition, including processes of chloroplast biogenesis, lipid metabolism, and molecular regulation (e.g. transcription factors, post-translational regulators, and phytohormones). This study demonstrates the wider physiological metabolic context that can determine cuticle deposition and lays the groundwork for new targets for modulating the properties of this protective barrier.

Organ Segmentation and Phenotypic Trait Extraction of Cotton Seedling Point Clouds Based on a 3D Lightweight Network

Cotton is an important economic crop; therefore, enhancing cotton yield and cultivating superior varieties are key research priorities. The seedling stage, a critical phase in cotton production, significantly influences the subsequent growth and yield of the crop. Therefore, breeding experts often choose to measure phenotypic parameters during this period to make breeding decisions. Traditional methods of phenotypic parameter measurement require manual processes, which are not only tedious and inefficient but can also damage the plants. To effectively, rapidly, and accurately extract three-dimensional phenotypic parameters of cotton seedlings, precise segmentation of phenotypic organs must first be achieved. This paper proposes a neural network-based segmentation algorithm for cotton seedling organs, which, compared to the average precision of 75.4% in traditional unsupervised learning, achieves an average precision of 96.67%, demonstrating excellent segmentation performance. The segmented leaf and stem point clouds are used for the calculation of phenotypic parameters such as stem length, leaf length, leaf width, and leaf area. Comparisons with actual measurements yield coefficients of determination R2 of 91.97%, 90.97%, 92.72%, and 95.44%, respectively. The results indicate that the algorithm proposed in this paper can achieve precise segmentation of stem and leaf organs, and can efficiently and accurately extract three-dimensional phenotypic structural information of cotton seedlings. In summary, this study not only made significant progress in the precise segmentation of cotton seedling organs and the extraction of three-dimensional phenotypic structural information, but the algorithm also demonstrates strong applicability to different varieties of cotton seedlings. This provides new perspectives and methods for plant researchers and breeding experts, contributing to the advancement of the plant phenotypic computation field and bringing new breakthroughs and opportunities to the field of plant science research.

The peculiarities of cell elongation growth of cereal coleoptiles under normal and flooding conditions

The review examines modern knowledge on the mechanisms of the early stages of plant cell elongation growth. Coleoptiles are used as a model object representing juvenile organs of cereal seedlings. Elongation growth is considered to be a protective morphophysiological stage of seedling development during hypogeal germination. The molecular mechanisms of elongation growth include: changes in the properties of the cell wall, activation of proton pumps, as well as aquaporins of plasma membrane and tonoplast. Particular attention is paid to the hormonal system of regulation, including auxin and ethylene. Coleoptiles of rice, a semi-aquatic plant tolerant to oxygen deficiency, demonstrate that the mechanisms of elongation growth are changing intensively under submergence, but they completely ensure cell growth. There is also a redistribution of importance and abundance between phytohormones. The data presented in the review indicate the necessity to continue investigations on the mechanisms of elongation growth under normal and stress conditions.

Anatomical and Agronomic Responses of Arabica Coffee Seedlings (Coffea arabica) to Addition of Nitrogen

The role of nitrogen in plant growth is well known, but there have been few studies on the response of nitrogen fertilizers to changes in plant anatomy and agronomy. This study aims to observe the response of the tissue and organs of arabica coffee seedlings to adding nitrogen. Nitrogen is used in the urea fertilizer form. This research used a single factor of CRD with five replications. 4 levels were tried without urea fertilizer as a control (N1), dosage of urea fertilizer 15 g urea.plant-1 is equivalent to 6,9 g of nitrogen (N2), dosage of urea fertilizer 30 urea.plant-1 is equivalent to 13,8 g of nitrogen (N3), and dosage of urea fertilizer urea.plant-1 is equivalent to 20,7 g of nitrogen (N4). After application, the plants are incubated for 30 days to allow time for the fertilizer to be absorbed by the plants. The analysis result stated that the chlorophyll content was very significantly different, while other agronomic variables were not significantly different. Less adaptation period was thought to be the cause of the various agronomic variables being not significantly different. This is reinforced by the response that arises in plant tissue. The addition of urea fertilizer responded to the thickness of the mesophyll tissue, the size of the epidermal cells, and the regularity of the lower epidermal cells. The result of this research concluded that the response of plants to the treatment had not yet reached the organ level but was still at the tissue level.

Strain-specific quantitative detection of two putative biocontrol strains for suppression of ash dieback

Plant diseases caused by microorganisms are a major threat to agricultural and forest ecosystems and production. The application of microorganisms as biocontrol agents can be a more sustainable way to suppress pathogens and/or strengthen plant health. In this study, we wanted to demonstrate an efficient way to monitor the inoculation success of promising bacterial strains on plants by qPCR, using the example of common ash and the bacterial strains Luteimonas fraxinea D4P002 and Aureimonas altamirensis C2P003. For the design of the strain-specific qPCR systems, we used a workflow mainly based on the comparison of a target genome with a reference genome database by the software Neptune. We were able to find specific sequences for both strains D4P002 and C2P003, and the designed qPCR systems were found to be highly sensitive, strain specific and the applied approach showed a high recovery rate from plant material. Strain-specific qPCR assays were applied to monitor the colonization and persistence of the two bacterial strains on ash seedlings eight weeks after inoculation. Both inoculated strains were found on different organs of the ash seedlings, with the highest abundance on the older inoculated leaves. On freshly grown plant parts, the inoculated strains could also be identified. The results of this study gave us the opportunity to establish an efficient way to trace inoculation success by specific quantification of the inoculated bacterial strains. Based on the described workflow, strain-specific detection systems can be easily designed for other biocontrol agents to observe their persistence after inoculation. The suggested procedure might be helpful in the evaluation of the biocontrol of plant diseases in horticulture, forestry or agriculture.

Genome-wide identification of HSF gene family and their expression analysis in vegetative tissue of young seedlings of hemp under different light treatments

Heat shock transcription factors (HSFs), play a crucial role in plant growth, development and defense processes. The functions of some HSFs have been well studied in response some stresses in model plants. At present, the genome of the medicinal plant Cannabis sativa L. has been fully sequenced. Nevertheless, there is little known about the HSF genes family in Cannabis sativa L, as well as a lack of understanding of its evolutionary history. Herein, 18 HSFs were identified in the cannabis genome and phylogenetically classified into three groups based on the structural characteristics and phylogenetic analysis, including classes A (9 genes), classes B (8 genes), and classes C (1 gene). They were distributed over 9 of 10 chromosomes without chromosome 8. Then, the motif composition and evolutionary relationship of CsHSF proteins are discussed in detail, along with gene structures, cis-acting elements in the promoter, and synchronization analysis. Furthermore, our results also revealed that CsHSF transcription levels varied significantly among tissues, suggesting that the functions of CsHSF may be different. Finally, we found that red and blue light treatments had a significant effect on HSF genes expression and cannabinoids accumulation in vegetative organs of hemp young seedlings, implying the expression of HSF genes may regulate the content of cannabinoids under different light conditions. Although cannabinoid biosynthesis and response to light in vegetative organs of hemp young seedlings may not represent the mature stage of hemp, these results provided an essential theoretical basis to elucidate the regulatory mechanism of HSF in cannabinoid biosynthesis in the future.

The content of soluble carbohydrates and proteins in the seedlings of soybean varieties with contrast photoperiodic response under the influence of selective light

Aim. Study of the influence of selective light irradiation on the content of soluble carbohydrates and proteins in the axial organs of seedlings of soybean varieties with a contrasting photoperiodic response (PPR). Methods. As plant material we used etiolated seedlings of soybean (Glycine max (L.) Merr.) SDP Khadjibei variety and DNP Yatran variety. Etiolated seedlings were irradiated daily for 30 minutes (5 days) using LED matrices with red, green and blue light. Then the material was fixed and a biochemical analysis was carried out in the axial organs of the seedlings – the content of soluble carbohydrates and proteins was determined. Results. GL and BL irradiation had the maximum effect on the content of soluble carbohydrates in SDP soybean seedlings of Khadjibey variety. In soybean seedlings of the DNP Yatran variety a significant effect was exerted by the action of all studied spectra, which was manifested in a decrease in their content in the above-ground part and growth in the root system. The content of proteins in seedlings of both varieties under the influence of selective light increased in both parts of the seedling. The most significant effect was observed for the irradiation of GL. Conclusions. The effects of selective light irradiation are manifested differently in shoots and roots, which may be due to the different composition or activity of the photoreceptor systems of the axial organs.

Understory junipers, and light environment effects on biomass, chemical composition, and nutrient contents of black pine seedlings

In forest environments, the establishment, survival, and recruitment of seedlings of desired species can often be influenced by biotic interactions between the competing understory shrubs and the seedlings, as well as by the understory light environment. Previous studies regarding competing effects were mostly focused on the survival and growth of seedlings, but it is still largely unclear how competition with shrubs impacts the biomass of the seedlings and physiological traits connected to photosynthesis and nitrogen metabolism in various forest ecosystems. Moreover, there is limited knowledge on the influence of light conditions on the biomass of understory seedlings is limited for different species. The main objectives of this study were to examine the effects of understory junipers and light conditions on the above and belowground biomass of black pine seedlings (Pinus nigra Arnold). This study also examined the changes in chemical composition and plant nutrient contents in the organs of black pine seedlings (i.e., root, stem, and needle) with the presence of junipers in the understory. Seedling biomass was significantly affected by understory light conditions, while the presence of junipers negatively affected the root-biomass of black pine seedlings. Moreover, understory junipers influenced some photosynthetic pigments in black pine seedlings.

Features of winter pea seeds germination under the action of growth regulators

Physiological features of pea seed germination under treatment with exogenous growth regulators based on biologically active substances were studied. Purpose. To investigate the influence of complex growth and development stimulators containing phytohormones and their analogs, Biosil and Gulliver Stimul, on the peculiarities of the seed germination processes and formation of the winter pea seedlings of the Moroz NS variety. Methods. Laboratory, measuring, weighing, quantitative, statistical. Results. The influence of aqueous solutions of growth regulators Biosil and Gulliver Stimul on the germination processes of winter pea seeds was analyzed. During research, it was established that the use of growth regulators contributes to the faster exit of seeds from the state of rest, which is illustrated by the active dynamics of germination. Treatment of winter pea seeds with growth regulators leads to an increase in germination energy by 10-12% and laboratory germination by 6-8% compared to the control. It was noted that the indicators of seed germination were sufficiently high in all samples, including control. The soaking in growth regulators solutions contributes to the 10-16 mg bigger swelling of seeds than in the control; better utilization of reserve compounds, and 38- 50 mg seed weight loss during germination. Phytohormones which are part of the preparations induced an increase in the development of the vegetative organs of pea seedlings, which was expressed in a rapid increase in the length of the shoot and root in experimental variants. The growth of the linear dimensions of the aboveground and underground parts of the seedlings was accompanied by the increase in the mass of raw material. Conclusions. Application of the Biosil and Gulliver Stimul composite plant growth regulators affects the processes of germination and the initial stages of growth of winter pea plants. Treatment of winter pea seeds with these preparations helps to improve seed germination and increase germination energy. The linear dimensions and mass of the raw matter of the roots and shoots of pea seedlings enlarged due to the influence of growth regulators. The maximum length of the root and shoot was observed under the use of Gulliver Stimul preparation

Changes in the Carbohydrate Profile in Common Buckwheat (Fagopyrum esculentum Moench) Seedlings Induced by Cold Stress and Dehydration.

Plant species are sensitive to stresses, especially at the seedling stage, and they respond to these conditions by making metabolic changes to counteract the negative effects of this. The objectives of this study were to determine carbohydrate profile in particular organs (roots, hypocotyl, and cotyledons) of common buckwheat seedlings and to verify whether carbohydrate accumulation is similar or not in the organs in response to cold stress and dehydration. Roots, hypocotyl, and cotyledons of common buckwheat seedlings have various saccharide compositions. The highest concentrations of cyclitols, raffinose, and stachyose were found in the hypocotyl, indicating that they may be transported from cotyledons, although this needs further studies. Accumulation of raffinose and stachyose is a strong indicator of the response of all buckwheat organs to introduced cold stress. Besides, cold conditions reduced d-chiro-inositol content, but did not affect d-pinitol level. Enhanced accumulation of raffinose and stachyose were also a distinct response of all organs against dehydration at ambient temperature. The process causes also a large decrease in the content of d-pinitol in buckwheat hypocotyl, which may indicate its transformation to d-chiro-inositol whose content increased at that time. In general, the sucrose and its galactosides in hypocotyl tissues were subject to the highest changes to the applied cold and dehydration conditions compared to the cotyledons and roots. This may indicate tissue differences in the functioning of the protective system(s) against such threats.

Alkaloidal variation in seedlings of Annona purpurea Moc. & Sessé ex Dunal infected with Colletotrichum gloeosporioides (Penz.) Penz. and Sacc.

Annona purpurea is a species of the Annonaceae family that more than 50 alkaloids. Some alkaloids carry out defense functions and can be grouped from an ecological perspective as constitutive and induced metabolites. The latter are expressed in response to changes in abiotic or biotic conditions that trigger stress in a plant. However, there are few systematic studies of constitutive metabolite profiles and their responses to biotic stress, despite the relevance of this concept. This work analyzed the differences in constitutive and induced alkaloids in A. purpurea seedlings infected with the phytopathogen Colletotrichum gloeosporioides. For this study, methanolic extracts of seedling leaves, stems, and roots inoculated with the fungus and not inoculated with the fungus were obtained and analyzed by gas chromatography coupled to mass spectrometry. The richness and abundance of alkaloids between the treatments and between organs were represented using the Margalef, Shannon, and Simpson ecological indices and the analysis of principal components, PERMANOVA, and paired PERMANOVA. Twenty-one alkaloids were detected from two biosynthetic pathways distributed in the seedling organs, and 15 of these alkaloids were considered constitutive because they are also found in adults. Most of the constitutive alkaloids in the seedlings were observed in the roots (15 compounds), followed by the stems (11 chemicals) and leaves (9 chemicals). The diversity indices also showed differences between the organs. Infection with the fungus modified the constitutive profile of the alkaloids by inducing an increase in lirinidine (61%) and papaverine (403%) in the roots and N,N-dimethyl, 2-(methylamino) 3-phenylindole (143%) in the leaves. Due to the infection, no new alkaloids were detected in any organ.

Diterpenes of Coffea seeds show antifungal and anti-insect activities and are transferred from the endosperm to the seedling after germination

Species of the genus Coffea accumulate diterpenes of the ent-kaurane family in the endosperm of their seeds, of which cafestol and kahweol are the most abundant. The diterpenes are mainly stored in esterified form with fatty acids, mostly palmitate. In contrast to the numerous studies on their effects on human health and therapeutic applications, nothing was previously known about their biological and ecological role in planta. The antifungal and anti-insect activities of cafestol and cafestol palmitate were thus investigated in this study. Cafestol significantly affected the mycelial growth of five of the six phytopathogenic fungi tested. It also greatly reduced the percentage of pupation of larvae and the pupae and adult masses of one of the two fruit flies tested. By contrast, cafestol palmitate had no significant effect against any of the fungi and insects studied. Using confocal imaging and oil body isolation and analysis, we showed that diterpenes are localized in endosperm oil bodies, suggesting that esterification with fatty acids enables the accumulation of large amounts of diterpenes in a non-toxic form. Diterpene measurements in all organs of seedlings recovered from whole seed germination or embryos isolated from the endosperm showed that diterpenes are transferred from the endosperm to the cotyledons during seedling growth and then distributed to all organs, including the hypocotyl and the root. Collectively, our findings show that coffee diterpenes are broad-spectrum defence compounds that protect not only the seed on the mother plant and in the soil, but also the seedling after germination.

Differential Effects of Ammonium (NH4+) and Potassium (K+) Nutrition on Photoassimilate Partitioning and Growth of Tobacco Seedlings

Plants utilize carbohydrates as the main energy source, but much focus has been on the impact of N and K on plant growth. Less is known about the combined impact of NH4+ and K+ nutrition on photoassimilate distribution among plant organs, and the resultant effect of such distribution on growth of tobacco seedlings, hence this study. Here, we investigated the synergetic effect of NH4+ and K+ nutrition on photoassimilate distribution, and their resultant effect on growth of tobacco seedlings. Soluble sugar and starch content peaks under moderate NH4+ and moderate K+ (2-2 mM), leading to improved plant growth, as evidenced by the increase in tobacco weight and root activity. Whereas, a drastic reduction in the above indicators was observed in plants under high NH4+ and low K+ (20-0.2 mM), due to low carbohydrate synthesis and poor photoassimilate distribution. A strong positive linear relationship also exists between carbohydrate (soluble sugar and starch) and the activities of these enzymes but not for invertase. Our findings demonstrated that NH4+ and K+-induced ion imbalance influences plant growth and is critical for photoassimilate distribution among organs of tobacco seedlings.

Manganese Deficiency Suppresses Growth and Photosynthetic Processes but Causes an Increase in the Expression of Photosynthetic Genes in Scots Pine Seedlings

Manganese deficiency is a serious plant nutritional disorder, resulting in the loss of crop productivity in many parts of the world. Despite the progress made in the study of angiosperms, the demand for Mn in gymnosperms and the physiological responses to Mn deficiency remain unexplored. We studied the influence of Mn deficiency for 24 weeks on Pinus sylvestris L. seedling growth, ion homeostasis, pigment contents, lipid peroxidation, chlorophyll fluorescence indices and the transcript levels of photosynthetic genes and genes involved in chlorophyll biosynthesis. It was shown that Mn-deficient plants demonstrated suppressed growth when the Mn content in the needles decreased below 0.34 µmol/g DW. The contents of photosynthetic pigments decreased when the Mn content in the needles reached 0.10 µmol/g DW. Mn deficiency per se did not lead to a decrease in the nutrient content in the organs of seedlings. Photoinhibition of PSII was observed in Mn-deficient plants, although this was not accompanied by the development of oxidative stress. Mn-deficient plants had an increased transcript abundance of genes (psbO, psbP, psbQ, psbA and psbC), encoding proteins directly associated with the Mn cluster also as other proteins involved in photosynthesis, whose activities do not depend on Mn directly. Furthermore, the transcript levels of the genes encoding the large subunit of Rubisco, light-dependent NADPH-protochlorophyllide oxidoreductase and subunits of light-independent protochlorophyllide reductase were also increased in Mn-deficient plants.

Photomorphogenesis and content of carbohydrates in the axial organs of field pean seedlings under the influence of selective light

Background: Light is a multifaceted exogenous factor that plays an important role in plant growth and development. The spectral composition of light is determinative for the regulation of photomorphogenetic processes in plants. Nowadays plants have several groups of photoreceptors that include receptors of red (RL) and far red light (FRL) — phytochromes; receptors of UV-A, blue (BL) and green (GL) light — cryptochromes, phototropins, proteins of the ZEITLUPE family, as well as the UV-B receptor — UVR8 protein. One of the possible mechanisms that realize an activation of photoreceptor systems in the plant may be concerned with carbohydrate metabolism. The research of morphogenetic reactions of seedlings under the action of selective light irradiation by activating photoreceptor systems is important for understanding the mechanisms of regulation of the program of plant organism`s ontogenesis. The aim of this study was to investigate the effect of selective light of different spectrum: RL (660 nm), GL (530 nm) and BL (450 nm) on growth reactions, morphogenesis and content of soluble carbohydrate in axial organs of seedlings of long-day plants. Materials and methods: 10-day etiolated seedlings of pea Maecenat variety were used for experiments. Activation of photoreceptor systems by red (RL, 660nm), green (GL, 530nm) and blue (BL, 450nm) light was performed for 5 days for 30 minutes using LED matrices. The growth reaction, morphogenesis and the content of soluble mono- and oligosugars in the axial organs of seedlings were analyzed. Results: The axial organs of seedlings differ in their response to irradiation with selective light. The root system is more sensitive to the action of selective light than the shoot of the seedlings of the long-day plants of the pea Maecenat variety. Activation of photoreceptor systems stimulates growth processes, activates the processes of photomorphogenesis and the biosynthesis of oligosugars de novo, most likely sucrose. Among the spectra of selective light, the maximum stimulating effect is shown by irradiation of the GL (530 nm) in the reactions of the aboveground part and roots. RL (660 nm) and BL (450 nm) show opposite effects: RL initiates a photomorphogenetic program of shoot part, and BL has a greater effect on photomorphogenesis of root system. Conclusions: Different levels of growth, morphogenetic processes and changes in the content of soluble carbohydrates are probably related to the ability of photoreceptor systems to activate the realization of different ways of photomorphogenesis in the axial organs of seedlings under the influence of selective light of a certain spectrum.

Proteomic and Metabolomic Revealed Differences in the Distribution and Synthesis Mechanism of Aroma Precursors in Yunyan 87 Tobacco Leaf, Stem, and Root at the Seedling Stage.

Tobacco, as an important cash crop and model plant, has been the subject of various types of research. The quality of flue-cured tobacco products depends on the compound collection of tobacco leaves, including pigments, carbohydrates, amino acids, polyphenols, and alkaloid aroma precursors. The present study investigates tobacco seedling organs (leaf, stem, and root) with the assistance of label-free proteomic technology and untargeted metabonomic technology. We analyzed 4992 proteins and 298 metabolites obtained in the leaf, stem, and root groups and found that there were significant differences in both primary and secondary metabolism processes involved in aroma precursor biosynthesis, such as carbohydrate metabolism, energy metabolism, and amino acid biosynthesis, and phenylpropanoid, flavonoid, and alkaloid biosynthesis. The findings showed that the contents of alkaloid metabolites such as nornicotine, anatabine, anatalline, and myosmine were significantly higher in tobacco roots than in leaves and stems at the seedling stage.

The effect of DC electric field on the elongation growth, proton extrusion and membrane potential of Zea mays L. coleoptile cells; a laboratory study

BackgroundIn this study, we investigated the effect of an electric field, with an intensity similar to that of the Earth’s field, on plant cells growth. The molecular mechanism underlying this effect remains unclear.ResultsIt was found that the electric field, depending on the applied voltage, its duration and the polarization of the maize seedlings, stimulated or inhibited the growth of the seedling organs (root, mesocotyl and coleoptile). Moreover, it was also noticed that the gravitropic response of maize seedlings was inhibited at all voltages studied. Simultaneous measurements of growth and external medium pH show that auxin(IAA, indole-3-acetic acid)- and fusicoccin(FC)-induced elongation growth and proton extrusion of maize coleoptile segments were significantly inhibited at higher voltages. The ionic current flowing through the single coleoptile segment during voltage application was 1.7-fold lower in segments treated with cation channel blocker tetraethylammonium chloride (TEA-Cl) and 1.4-fold higher with IAA compared to the control. The electrophysiological experiments show that the electric field caused the depolarization of the membrane potential of parenchymal coleoptile cells, which was not reversible over 120 min.ConclusionIt is suggested that a DC electric field inhibits the plasma membrane H+ pump activity and K+ uptake through voltage-dependent, inwardly rectifying ZMK1 channels (Zea mays K+ channel 1). The data presented here are discussed, taking into account the “acid growth hypothesis” of the auxin action and the mechanism of gravitropic response induction.