Response Of Seedlings Research Articles

Exogenous acetone O-(2-naphthylsulfonyl)oxime improves the adverse effects of excess copper by copper detoxification systems in maize

The current study is to elucidate the responses of maize seedlings to excess copper and acetone O-(2-naphthylsulfonyl)oxime (NS) pretreatment. The study was divided into the following experimental groups: 18 h distilled water (DW) control (C), 6 h 0.3 mM NS + then 12 h DW (NS), 6 h DW + then 12 h 1 mM CuSO4.5H2O (CuS), 0.3 mM NS for 6 h + then 1 mM CuSO4.5H2O (NS + CuS) for 12 h. When the NS + CuS group is compared with the CuS group; It accumulated 10% more copper, while the ABA, H2O2, MDA, and carotenoid contents decreased significantly, the total chlorophyll, proline, gallic acid, ascorbic acid, catechol, trans-P-qumaric acid, and cinnamic acid contents increased. While SOD activity, which is one of the antioxidant system enzymes, decreased with NS application, GPX, CAT, and APX activities increased despite copper stress. When all the findings are evaluated as a whole, exogenous NS, despite excessive copper, ameliorated the adverse effects of copper stress by increasing the effectiveness of the enzymatic and non-enzymatic components of the antioxidant system and the contents of phenolic substances. In addition, increasing the copper content by 10% reveals its importance in terms of NS phytoremediation. Abbreviation: Style-sheet: When full form and abbreviated form both are used as keywords, retain both as provided by the author

Multifunctionality of Jasmonic Acid Accumulation during Aphid Infestation in Altering the Plant Physiological Traits That Suppress the Plant Defenses in Wheat Cultivar XN979.

Crop plants have coevolved phytohormone-mediated defenses to combat and/or repel their colonizers. The present study determined the effects of jasmonic acid (JA) accumulation during aphid infestation on the preference and performance of Sitobion miscanthi Takahashi (Hemiptera: Aphididae), and its potential role in fine-tuning hormone-dependent responses in XN979 wheat cultivar seedlings was evaluated via the transcriptional profiles of marker genes related to JA- and salicylic acid (SA)-dependent responses. The preference experiment and the life table data reveal that direct foliage spraying of 2.5 mM methyl jasmonate (MeJA) exhibited weak negative or positive effects on the preferential selection and the population dynamics and oviposition parameters of S. miscanthi. The transcription level of phytohormone biosynthesis genes shows that foliage spraying of MeJA significantly upregulated the marker genes in the JA biosynthesis pathway while downregulating the SA pathway. In addition, either MeJA treatment or previous aphid infestation significantly induced upregulated transcription of the genes involved in the JA- and SA-dependent defense responses, and the transcription level of the tryptophan decarboxylase (TaTDC) gene, which facilitates the conversion of L-tryptophan to tryptamine, was rapidly upregulated after the treatments as well. The main products of tryptamine conversion could play a crucial role in suppressing SA-dependent defense responses. These results will provide more experimental evidence to enable understanding of the antagonistic interaction between hormone signaling processes in cereals under aphid infestation.

Effects of Bio- and Chemical Fertilizers on Growth and Soil Microbial Population of Cacao (Theobroma cacao L.) Seedlings

A comparative study was done to determine the growth, microbial population, and physico- chemical properties on UF18 cacao (Theobroma cacao) seedlings when treated with chemical fertilizers and biofertilizers, either applied singly or in combination. The experimental design was randomized completely block design with five seedlings per treatment per block. Treatments used were: control, ½ recommended rate of chemical (RRC) fertilizer, RRC, MYKORICH®, MYKOCAP®, ½ RRC + MYKORICH®, ½ RRC + MYKOCAP®, RRC + MYKORICH®, and RRC + MYKOCAP®. MYKORICH® and MYKOCAP® contain 12 species of arbuscular mycorrhizal fungi isolated from stressed environments. The results showed that plant growth and physico-chemical properties were significantly improved by the application of biofertilizer than by chemical fertilizer. MYKORICH® treatment gave the highest spore count and is highly significant (p < 0.05) as compared to the other treatments with spore count ranging from 41–115.5/ 50 g soil. In terms of nitrogen-fixing bacteria count, ½ RRC treatment gave the highest (16.9 CFU x 10–5 g soil–1) bacterial count. RRC + MYKORICH® inoculation gave the highest values for most of the soil physico-chemical analysis (pH, P, K, and CEC). The positive response of cacao seedlings to mycorrhizal inoculation with or without chemical fertilizer provides a useful criterion in other agricultural lands throughout the country for crop production and sustainability.

Effects of exogenous abscisic acid on antioxidant system of salt tolerant and salt sensitive cotton cultivars

Summary Salinity is one of the most imperative global problems that affect crop productivity on a large scale. Salinity impairs plant growth and development by imposing various stresses. Therefore it is vital to decode those stress factors and identify possible solutions to improve agriculture productivity. However, the adaptive mechanisms under saline conditions of glycophytes have not been studied. The present study was undertaken to determine the effects of exogenous abscisic acid (ABA) on salinity tolerance in cotton plants. Some patterns of resistance development were revealed on the seedlings of two cotton cultivars, a salt-tolerant (Gulistan) and a salt-sensitive one (C-4727). Moreover, the antioxidant potentials of these cultivars were compared. The activities of ascorbate peroxidase (APX), super-oxide dismutase (SOD), as well as the quantity of endogenous ABA, malondialdehyde (MDA), and free proline (Pro) were determined in control and post treatment. Our results demonstrate significant differences between the salt- tolerant and sensitive cotton seedlings in response to saline stress, i.e., high levels of Pro and endogenous ABA, but lower MDA concentrations, and higher activity of APX and SOD for the salt-tolerant cultivar, Gulistan, as compared to the salt stress-sensitive cultivar C-4727.

Growth Responses of Clove Seedlings (Sizigium aromaticum L) to Natural Auxin and Household Waste Media

Indonesia is the number 1 clove producing country in the world, in amount of 140,812 tons (The Ministry of Indonesian Agriculture, 2022). Cloves are commonly used as a flavor enhancer for food and drinks. Its warm and spicy sensation is quite popular among people, especially those who live in cold areas. In addition, cloves are also useful for aromatic mixture of cigarettes. In addition, cloves are also good for the health of the body because they are known contain phosphorus, iron, magnesium, calcium, potassium, zinc, sodium and vitamins. This study aims were to determine the optimum concentration of organic auxin and the effect of using household waste media on the growth of clove plant seedlings. This study used a factorial experimental method which was arranged in a Completely Randomized Design (CRD) consisting of two factors. The first factor was the dose of household waste consisting of L0 = no household waste (control/ only with 2.5 g NPK fertilizer); L1 = household waste 10%; L2 = household waste 20% and L3 = household waste 30%. The second factor was the type of organic auxins, which consist of A0 = without organic auxin; A1 = red onion organic auxin; A2 = tomato organic auxin; A3 = auxin organic mung bean sprouts. Each treatment was repeated 4 times, resulting in 64 experimental units. The results showed that there was no interaction between the dose of household waste and natural auxins on the growth of clove seedling. Household waste can replace NPK fertilizer starting from a dose of 10 g/plant. Kinds of natural auxin did not affect the growth of clove seedlings. The seedling cultivation is enough profitable.

Early leaf responses of cell physiological and sensor-based signatures reflect susceptibility of wheat seedlings to infection by leaf rust.

Leaf rust caused by Puccinia triticina Erikss. can have devastating effects on wheat (Triticum aestivum L.), causing severe economic losses. This comprehensive study serves to facilitate our understanding of the impact of carbohydrate and antioxidant metabolism in association with sensor-based phenotyping and leaf rust stress responses in wheat seedlings. After 24 h of inoculation (hai) very susceptible variety to leaf rust (Ficko) increased cell-wall invertase (cwInv; EC 3.2.1.26), compared to other varieties that significantly increased cwInv later. This could mean that the Ficko variety cannot defend itself from leaf rust infections once symptoms have started to develop. Also, Ficko had significantly decreased amounts of cytoplasmic invertase (cytInv; EC 3.2.1.26) at 8 hai. The downregulation of cytInv in susceptible plants may facilitate the maintenance of elevated apoplastic sucrose availability favoring the pathogen. The significant role of vacuolar invertase (vacInv; EC 3.2.1.26) in moderately resistant varieties was recorded. Also, a significant decrease of glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) and UDP-glucose pyrophosphorylase (UGPase; EC 2.7.7.9) in moderately resistant varieties might restrict normal development of leaf rust due to reduced sugar. During plant-pathogen interaction, when the invader spreads systemically throughout the plant, the main role of ascorbate peroxidase (APX; EC 1.11.1.11) activity in one moderately resistant variety (Olimpija) and catalase (CAT; EC 1.11.1.6) activity in another moderately resistant variety (Alka) is to protect the plant against oxidative damage in the early stages of infection. Non-invasive phenotyping with a sensor-based technique could be used as a rapid method for pre-symptomatic determination of wheat leaf rust resistance or susceptibility.

The Influence of Lead and Acyrthosiphon pisum (Harris) on Generation of Pisum sativum Defense Signaling Molecules and Expression of Genes Involved in Their Biosynthesis.

The main aim of this study was to understand the regulation of the biosynthesis of phytohormones as signaling molecules in the defense mechanisms of pea seedlings during the application of abiotic and biotic stress factors. It was important to identify this regulation at the molecular level in Pisum sativum L. seedlings under the influence of various concentrations of lead-i.e., a low concentration increasing plant metabolism, causing a hormetic effect, and a high dose causing a sublethal effect-and during feeding of a phytophagous insect with a piercing-sucking mouthpart-i.e., pea aphid (Acyrthosiphon pisum (Harris)). The aim of the study was to determine the expression level of genes encoding enzymes of the biosynthesis of signaling molecules such as phytohormones-i.e., jasmonates (JA/MeJA), ethylene (ET) and abscisic acid (ABA). Real-time qPCR was applied to analyze the expression of genes encoding enzymes involved in the regulation of the biosynthesis of JA/MeJA (lipoxygenase 1 (LOX1), lipoxygenase 2 (LOX2), 12-oxophytodienoate reductase 1 (OPR1) and jasmonic acid-amido synthetase (JAR1)), ET (1-aminocyclopropane-1-carboxylate synthase 3 (ACS3)) and ABA (9-cis-epoxycarotenoid dioxygenase (NCED) and aldehyde oxidase 1 (AO1)). In response to the abovementioned stress factors-i.e., abiotic and biotic stressors acting independently or simultaneously-the expression of the LOX1, LOX2, OPR1, JAR1, ACS3, NCED and AO1 genes at both sublethal and hormetic doses increased. Particularly high levels of the relative expression of the tested genes in pea seedlings growing at sublethal doses of lead and colonized by A. pisum compared to the control were noticeable. A hormetic dose of lead induced high expression levels of the JAR1, OPR1 and ACS3 genes, especially in leaves. Moreover, an increase in the concentration of phytohormones such as jasmonates (JA and MeJA) and aminococyclopropane-1-carboxylic acid (ACC)-ethylene (ET) precursor was observed. The results of this study indicate that the response of pea seedlings to lead and A. pisum aphid infestation differed greatly at both the gene expression and metabolic levels. The intensity of these defense responses depended on the organ, the metal dose and direct contact of the stress factor with the organ.

Titanium dioxide nanoparticles require K+ and hydrogen sulfide to regulate nitrogen and carbohydrate metabolism during adaptive response to drought and nickel stress in cucumber

Crop plants face severe yield losses worldwide owing to their exposure to multiple abiotic stresses. The study described here, was conducted to comprehend the response of cucumber seedlings to drought (induced by 15% w/v polyethylene glycol 8000; PEG) and nickel (Ni) stress in presence or absence of titanium dioxide nanoparticle (nTiO2). In addition, it was also investigated how nitrogen (N) and carbohydrate metabolism, as well as the defense system, are affected by endogenous potassium (K+) and hydrogen sulfide (H2S). Cucumber seedlings were subjected to Ni stress and drought, which led to oxidative stress and triggered the defense system. Under the stress, N and carbohydrate metabolism were differentially affected. Supplementation of the stressed seedlings with nTiO2 (15 mg L−1) enhanced the activity of antioxidant enzymes, ascorbate-glutathione (AsA-GSH) system and elevated N and carbohydrates metabolism. Application of nTiO2 also enhanced the accumulation of phytochelatins and activity of the enzymes of glyoxalase system that provided additional protection against the metal and toxic methylglyoxal. Osmotic stress brought on by PEG and Ni, was countered by the increase of proline and carbohydrates levels, which helped the seedlings keep their optimal level of hydration. Application nTiO2 improved the biosynthesis of H2S and K+ retention through regulating Cys biosynthesis and H+-ATPase activity, respectively. Observed outcomes lead to the conclusion that nTiO2 maintains redox homeostasis, and normal functioning of N and carbohydrates metabolism that resulted in the protection of cucumber seedlings against drought and Ni stress. Use of 20 mM tetraethylammonium chloride (K+- channel blocker), 500 μM sodium orthovanadate (PM H+-ATPase inhibitor), and 1 mM hypotaurine (H2S scavenger) demonstrate that endogenous K+ and H2S were crucial for the nTiO2-induced modulation of plants' adaptive responses to the imposed stress.

Effects of exogenous calcium on growth, chlorophyll fluorescence characteristics and antioxidant system of Fraxinus malacophylla seedlings

Karst ecosystems are becoming increasingly problematic, and high calcium is one of the main characteristics of soils in rocky desertification areas. Chlorophyll fluorescence is one of the most important indicators of the extent to which plants are affected by their environment. There are few reports on the effects of changes in exogenous calcium levels on the chlorophyll fluorescence properties of Fraxinus malacophylla seedlings. In the present study, we investigated the growth, chlorophyll fluorescence properties and antioxidant system of Fraxinus malacophylla seedlings in response to exogenous calcium (as the concentrations of 0, 25, 50, 75 mmol L−1). The results showed that Ca2+ concentration (25–50 mmol L−1) treatment mainly promoted the growth, biomass accumulation, root activity, and chlorophyll synthesis and effect on chlorophyll fluorescence in Fraxinus malacophylla; the developed root system became a strong linking hub for calcium adaptation. In addition, the activities of the antioxidant enzymes peroxidase (POD) and catalase (CAT) are upregulated and play an important role in preventing excessive oxidative damage. OJIP test parameters changed significantly with the addition of exogenous calcium, and parameters related to each photosystem II (PSII) reaction centre, such as ABS/RC and DIo/RC, increased significantly in the OJIP test, with enhanced function of the PSII electron donor lateral oxygen evolution complex. In conclusion, the addition of exogenous calcium (25–50 mmol L−1) had an important protective effect on the photosynthetic mechanism of Fraxinus malacophylla, promoting photosynthesis, better growth and better adaptability.

Molecular defense responses to natural enemies determine seedling survival in a subtropical forest

Negative density dependence (NDD) has been accepted as a key mechanism for biodiversity maintenance in natural forests and different lineages of natural enemies (fungus, bacterium, insect and virus) may be involved. Previous NDD related studies usually correlated seedling survival to the density of host-specific pests or pathogens along the physical distance to conspecific neighbors, and molecular defense responses of focal seedlings to natural enemies were seldom concerned. By employing a community functional genomic strategy, we extracted copy numbers of homologous genes in defense responses from transcriptomic data of 99 tree species and their inherent impacts on seedling survival were evaluated using linear mixed-effects models (LMMs) and general linear mixed-effects models (GLMMs). The copy number of fungus-defense, insect-defense, and virus-defense genes showed significant negative correlations with survival rates of the seedling community and the copy number of insect-defense genes significantly and negatively correlated with survival rates of top-twenty common species. Seedlings tended to have high survival rates when surrounded by seedling neighbors with similar insect-defense CNV matrices and adult neighbors with distinct bacterium-defense and virus-defense CNV matrices.We conclude that both gene copy number and dissimilarities to adult and seedling neighbors in defense response to natural enemies contributed to seedling survival, indicating the critical contributions of molecular defense responses of plants to species coexistence and diversity maintenance in subtropical forests.

Revealing the molecular basis regulating the iron deficiency response in quinoa seedlings by physio-biochemical and gene expression profiling analyses

Revealing the molecular basis regulating the iron deficiency response in quinoa seedlings by physio-biochemical and gene expression profiling analyses

Biometric and morphological adjustments of Eugenia. dysenterica DC. seedlings in response to increased soil water deficit

Water stress can affect all aspects of plant growth and development, compromising its productive potential. The cultivation of fruit species native to the Cerrado and the study of their behavior under conditions of low water availability are necessary activities, in view of their socioeconomic and environmental potential. This study was conducted to evaluate the effect of water deficit on growth and biomass production of the cagaita tree (Eugenia dysenterica DC.), a species endemic to the Cerrado (Brazilian Savannah). The experiment was performed in a greenhouse for 120 days in a randomized block design (RBD), with a double factorial arrangement (2x5), corresponding to two cagaita mother plants and five water conditions. We evaluated the growth and leaf, stem and root functional characteristics. The most severe water deficit conditions reduced shoot growth, number of leaves, production of biomass and dry matter and increased the specific and per plant mass root length of cagaita plants. Deficit extension had negative effects on its growth and development. There was a statistical difference between mother plants, with mother plant 2 being more resistant to drought. The application of a severe or longer water deficit affected shoot growth and reduced the appearance of new leaves. The stress caused by water deficiency allowed an increase in root functional characteristics, supporting the hypothesis that plants under adverse conditions focus on higher biomass production and convert a higher amount of dry matter into the roots. Leaf area did not show to be a functional characteristic, explaining the stress effects in E. dysenterica DC plants.

Defence-related metabolic changes in wheat (Triticum aestivum L.) seedlings in response to infection by Puccinia graminis f. sp. tritici.

Stem rust caused by the pathogen Puccinia graminis f. sp. tritici is a destructive fungal disease-causing major grain yield losses in wheat. Therefore, understanding the plant defence regulation and function in response to the pathogen attack is required. As such, an untargeted LC-MS-based metabolomics approach was employed as a tool to dissect and understand the biochemical responses of Koonap (resistant) and Morocco (susceptible) wheat varieties infected with two different races of P. graminis (2SA88 [TTKSF] and 2SA107 [PTKST]). Data was generated from the infected and non-infected control plants harvested at 14- and 21- days post-inoculation (dpi), with 3 biological replicates per sample under a controlled environment. Chemo-metric tools such as principal component analysis (PCA), orthogonal projection to latent structures-discriminant analysis (OPLS-DA) were used to highlight the metabolic changes using LC-MS data of the methanolic extracts generated from the two wheat varieties. Molecular networking in Global Natural Product Social (GNPS) was further used to analyse biological networks between the perturbed metabolites. PCA and OPLS-DA analysis showed cluster separations between the varieties, infection races and the time-points. Distinct biochemical changes were also observed between the races and time-points. Metabolites were identified and classified using base peak intensities (BPI) and single ion extracted chromatograms from samples, and the most affected metabolites included flavonoids, carboxylic acids and alkaloids. Network analysis also showed high expression of metabolites from thiamine and glyoxylate, such as flavonoid glycosides, suggesting multi-faceted defence response strategy by understudied wheat varieties towards P. graminis pathogen infection. Overall, the study provided the insights of the biochemical changes in the expression of wheat metabolites in response to stem rust infection.

Response of Ammodendron bifolium Seedlings Inoculated with AMF to Drought Stress

Drought has become a serious environmental problem affecting people all around the world as a result of rising atmospheric pollution and global warming. Through symbiosis with Arbuscular mycorrhizal fungus (AMF), plants may mitigate the impacts of drought stress on growth and development as well as physiological metabolism. As a pioneer plant for windbreak and sand fixation, the symbiosis between AMF and Ammodendron bifolium can improve its drought resistance, which is of great significance for species protection and desertification control. In this study, A. bifolium seedlings were used as the test subject in a pot experiment with four drought stress gradients and two inoculation treatments to examine the effects of water treatment and AMF inoculation on the growth of the seedlings. The results showed that drought stress significantly inhibited the growth indexes of A. bifolium seedlings such as the height, basal diameter, blades number, and biomass, and that inoculation with AMF could promote the growth of A. bifolium seedlings and help mitigate the damage caused by drought stress. Drought stress increased the antioxidant enzyme activity and proline (Pro) accumulation in A. bifolium plants, and AMF inoculation induced higher antioxidant enzyme activity and lower malondialdehyde (MDA) and Pro contents in A. bifolium seedlings compared to non-AMF-inoculated plants. Drought stress harmed the chloroplast structure, reduced the chlorophyll concentration, and decreased the photosynthetic efficiency in A. bifolium seedlings. The ability of AMF-inoculated plants to withstand drought was enhanced by increased levels of photosynthetic pigments, higher photosynthetic activity, and increased photosynthetic product accumulation in the roots. These results suggest that AMF inoculation can alleviate drought-induced damage by promoting plant growth and improving plant antioxidant, osmoregulation, and photosynthetic capacity. In the context of increasing drought due to global warming, AMF inoculation can be an excellent way to enhance A. bifolium drought resistance.

Dynamic Translational Landscape Revealed by Genome-Wide Ribosome Profiling under Drought and Heat Stress in Potato.

The yield and quality of potatoes, an important staple crop, are seriously threatened by high temperature and drought stress. In order to deal with this adverse environment, plants have evolved a series of response mechanisms. However, the molecular mechanism of potato's response to environmental changes at the translational level is still unclear. In this study, we performed transcriptome- and ribosome-profiling assays with potato seedlings growing under normal, drought, and high-temperature conditions to reveal the dynamic translational landscapes for the first time. The translational efficiency was significantly affected by drought and heat stress in potato. A relatively high correlation (0.88 and 0.82 for drought and heat stress, respectively) of the fold changes of gene expression was observed between the transcriptional level and translational level globally based on the ribosome-profiling and RNA-seq data. However, only 41.58% and 27.69% of the different expressed genes were shared by transcription and translation in drought and heat stress, respectively, suggesting that the transcription or translation process can be changed independently. In total, the translational efficiency of 151 (83 and 68 for drought and heat, respectively) genes was significantly changed. In addition, sequence features, including GC content, sequence length, and normalized minimal free energy, significantly affected the translational efficiencies of genes. In addition, 28,490 upstream open reading frames (uORFs) were detected on 6463 genes, with an average of 4.4 uORFs per gene and a median length of 100 bp. These uORFs significantly affected the translational efficiency of downstream major open reading frames (mORFs). These results provide new information and directions for analyzing the molecular regulatory network of potato seedlings in response to drought and heat stress.

Effects of sand burial on seedling growth of the coastal dune plant Viola grayi: Tolerance and adaptive responses to sand accretion

AbstractThe responses of Viola grayi seedlings to complete sand burial were experimentally assessed in this study. Approximately 10‐month‐old seedlings were buried in sand to a depth of 0, 1, 5, or 15 cm. The re‐emerged seedlings were counted for 5 months, and the dry weights were compared. The results showed that shallow burial promoted the shoot development and total growth of seedlings. The dry weights of stems and leaves and the total dry weight of seedlings were higher in plants buried at depths of 1 and 5 cm than in unburied plants. The dry weight of roots did not differ among them. No seedlings buried at a 15‐cm depth re‐emerged. Most seedlings buried at 1‐ and 5‐cm depths produced adventitious roots from below‐ground stems. The tolerance and adaptive responses of V. grayi seedlings to sand accretion may contribute to their establishment in sand‐accumulating habitats.

Root Growth and Defense Response of Seedlings against Fusarium oxysporum in Sand Culture and In Vitro—A Comparison of Two Screening Approaches for Asparagus Cultivars

Two rapid asparagus (Asparagus officinalis L.) screening methods, in sand culture and in vitro, were tested to evaluate the response of young seedlings against F. oxysporum f. sp. asparagi (isolate Foa1). Root morphological parameters were evaluated and correlated with the symptomatology and expression of the defense-related genes at 5 and 7 dpi. In sand cultivation, the Foa1-inoculated cultivars showed no visible disease symptoms on their roots until 7 dpi. Two-factorial ANOVA statistics found no significant interaction between the cultivars and treatments for most root parameters but some differences between the cultivars. The in vitro Foa1-inoculated cultivars showed high susceptibility according to their symptomatology and differed greatly in the length of the primary root at 5 dpi. In some cultivars, the primary root length and root surface area were higher upon Foa1 inoculation. The expression changes were very different among the cultivars, with significant induction of PR1, POX, and PAL at 5 dpi in all cultivars in vitro but only in two cultivars in sand cultivation. The in vitro screening method, although more artificial, seemed to be more reliable than sand cultivation since the fungus was able to develop well in the culture medium. In sand-filled pots, the fungus may have been hindered in its development, even though a considerable higher amount of Foa1 was inoculated. In addition, the fungal growth was easily trackable in tubes, while in sand cultivation, the results were only visible after pulling the seedlings out of the pots 12 dpi.

Combined transcriptomic and metabolomic analyses of high temperature stress response of quinoa seedlings

BackgroundQuinoa (Chenopodium quinoa Willd.) originates in high altitude areas, such as the Andes, and has some inherent characteristics of cold, drought, and salinity tolerance, but is sensitive to high temperature.ResultsTo gain insight into the response mechanism of quinoa to high temperature stress, we conducted an extensive targeted metabolomic study of two cultivars, Dianli-3101 and Dianli-3051, along with a combined transcriptome analysis. A total of 794 metabolites and 54,200 genes were detected, in which the genes related to photosynthesis were found down-regulated at high temperatures, and two metabolites, lipids and flavonoids, showed the largest changes in differential accumulation. Further analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and transcription factors revealed that quinoa inhibits photosynthesis at high temperatures, and the possible strategies being used for high temperature stress management are regulation of heat stress transcription factors (HSFs) to obtain heat tolerance, and regulation of purine metabolism to enhance stress signals for rapid response to high temperature stress. The tolerant genotype could have an enhanced response through lower purine levels. The induction of the stress response could be mediated by HSF transcription factors. The results of this study may provide theoretical references for understanding the response mechanism of quinoa to high temperature stress, and for screening potential high temperature tolerant target genes and high temperature tolerant strains.ConclusionsThese findings reveal the regulation of the transcription factor family HSF and the purinergic pathway in response to high temperature stress to improve quinoa varieties with high temperature tolerance.

Time-Series Transcriptomic Analysis of Contrasting Rice Materials under Heat Stress Reveals a Faster Response in the Tolerant Cultivar.

Short-term heat stress can affect the growth of rice (Oryza sativa L.) seedlings, subsequently decreasing yields. Determining the dynamic response of rice seedlings to short-term heat stress is highly important for accelerating research on rice heat tolerance. Here, we observed the seedling characteristics of two contrasting cultivars (T11: heat-tolerant and T15: heat-sensitive) after different durations of 42 °C heat stress. The dynamic transcriptomic changes of the two cultivars were monitored after 0 min, 10 min, 30 min, 1 h, 4 h, and 10 h of stress. The results indicate that several pathways were rapidly responding to heat stress, such as protein processing in the endoplasmic reticulum, glycerophospholipid metabolism, and plant hormone signal transduction. Functional annotation and cluster analysis of differentially expressed genes at different stress times indicate that the tolerant cultivar responded more rapidly and intensively to heat stress compared to the sensitive cultivar. The MAPK signaling pathway was found to be the specific early-response pathway of the tolerant cultivar. Moreover, by combining data from a GWAS and RNA-seq analysis, we identified 27 candidate genes. The reliability of the transcriptome data was verified using RT-qPCR on 10 candidate genes and 20 genes with different expression patterns. This study provides valuable information for short-term thermotolerance response mechanisms active at the rice seedling stage and lays a foundation for breeding thermotolerant varieties via molecular breeding.

Impact of warm spells during late fall and winter on frost hardiness of short-day treated Norway spruce seedlings

Warm spells during the late fall and winter are expected to become more frequent in boreal areas due to climate change. The aims of our study were to investigate whether warm spells in the late fall and winter cause deacclimation of Norway spruce (Picea abies (L.) Karst.) seedlings, whether the seedlings are capable of reacclimating in response to a subsequent cold period, and whether a short-day (SD) treatment applied in a nursery affects seedlings’ responses to warm and cold spells during the non-growing season (hereafter off-season). During the preceding growing season, the seedlings were treated either with a SD treatment (SD1: June 29 – July 20 or SD2: July 20 – August 10) or were grown in a natural photoperiod. The seedlings were artificially exposed to a 7-day warm spell, followed by a 7-day cold spell on four occasions (late fall: October and November; winter: January and March). The frost hardiness of the needles and the probability of bud damage were determined before and after the warm spell and after the cold spell. The dormancy status of the seedlings was also determined. Warm spells reduced the frost hardiness in needles and increased the probability of bud damage in January and March, but not in October and November. Needles were able to reacclimate from November to January, and buds also in early March. Our results indicate that in boreal areas, warm spells followed by low temperatures may predispose Norway spruce seedlings to freezing damage later in the winter, but not in the late fall. The seedlings that received SD2 treatment retained an ability to reacclimate after a warm spell in March, unlike the seedlings in the other photoperiod treatments, indicating that the responses of seedlings to the fluctuating temperature conditions in winter are affected by the growth conditions during the previous growing season. Therefore, the use and timing of SD treatment may affect survival of fall-planted seedlings and seedlings that overwinter outdoors in nurseries, especially during snowless winters.