Small but powerful: RALF peptides in plant adaptive and developmental responses.

Plants live in a highly dynamic environment and require to rapidly respond to a plethora of environmental stimuli, so that to maintain their optimal growth and development. A small plant peptide, rapid alkalization factor (RALF), can rapidly increase the pH value of the extracellular matrix in plant cells. RALFs always function with its corresponding receptors. Mechanistically, effective amount of RALF is induced and released at the critical period of plant growth and development or under different external environmental factors. Recent studies also highlighted the role of RALF peptides as important regulators in plant intercellular communications, as well as their operation in signal perception and as ligands for different receptor kinases on the surface of the plasma membrane, to integrate various environmental cues. In this context, understanding the fine-print of above processes may be essential to solve the problems of crop adaptation to various harsh environments under current climate trends scenarios, by genetic means. This paper summarizes the current knowledge about the structure and diversity of RALF peptides and their roles in plant development and response to stresses, highlighting unanswered questions and problems to be solved.

A two-sequence motif-based method for the inventory of gene families in fragmented and poorly annotated genome sequences.

Databases of genome sequences are growing exponentially, but, in some cases, assembly is incomplete and genes are poorly annotated. For evolutionary studies, it is important to identify all members of a given gene family in a genome. We developed a method for identifying most, if not all, members of a gene family from raw genomes in which assembly is of low quality, using the P-type ATPase superfamily as an example. The method is based on the translation of an entire genome in all six reading frames and the co-occurrence of two family-specific sequence motifs that are in close proximity to each other. To test the method's usability, we first used it to identify P-type ATPase members in the high-quality annotated genome of barley (Hordeum vulgare). Subsequently, after successfully identifying plasma membrane H+-ATPase family members (P3A ATPases) in various plant genomes of varying quality, we tested the hypothesis that the number of P3A ATPases correlates with the ability of the plant to tolerate saline conditions. In 19 genomes of glycophytes and halophytes, the total number of P3A ATPase genes was found to vary from 7 to 22, but no significant difference was found between the two groups. The method successfully identified P-type ATPase family members in raw genomes that are poorly assembled.

Reactive oxygen species- and nitric oxide-dependent regulation of ion and metal homeostasis in plants.

Deterioration and impoverishment of soil, caused by environmental pollution and climate change, result in reduced crop productivity. To adapt to hostile soils, plants have developed a complex network of factors involved in stress sensing, signal transduction, and adaptive responses. The chemical properties of reactive oxygen species (ROS) and reactive nitrogen species (RNS) allow them to participate in integrating the perception of external signals by fine-tuning protein redox regulation and signal transduction, triggering specific gene expression. Here, we update and summarize progress in understanding the mechanistic basis of ROS and RNS production at the subcellular level in plants and their role in the regulation of ion channels/transporters at both transcriptional and post-translational levels. We have also carried out an in silico analysis of different redox-dependent modifications of ion channels/transporters and identified cysteine and tyrosine targets of nitric oxide in metal transporters. Further, we summarize possible ROS- and RNS-dependent sensors involved in metal stress sensing, such as kinases and phosphatases, as well as some ROS/RNS-regulated transcription factors that could be involved in metal homeostasis. Understanding ROS- and RNS-dependent signaling events is crucial to designing new strategies to fortify crops and improve plant tolerance of nutritional imbalance and metal toxicity.

Effects of iron oxide nanoparticles (Fe3O4) and salinity on growth, photosynthesis, antioxidant activity and distribution of mineral elements in wheat (Triticum aestivum).

Soil salinisation is one of the main abiotic stresses decreasing crop productivity. Here, we show that the plant treatment with iron oxide (Fe3 O4 ) nanoparticles (NPs) may be a promising solution for reducing the negative impact of soil salinity on plant performance. For this purpose, effects of the NPs on growth, photosynthesis, pro-/antioxidant, redox balance and the content of mineral elements in 19-day-old wheat (Triticum aestivum ) plants under soil salinity were studied. Seed treatment with NPs (200 and 500mg L-1 ) enhanced growth and photosynthetic rate in leaves. Moderate salinity stress (150mMNaCl) led to a decrease in plant biomass as well as the rate of photosynthesis and PSII activity; leaf photosynthetic characteristics were also suppressed by lower (75mMNaCl) salinity treatment. However, seed pre-treatment with the NPs partially eliminated the negative effect of the salt on growth, PSII activity and photosynthesis. Also, we observed a decrease in the content of malondialdehyde (MDA) and an increase in ascorbate and total peroxidase activity in the plant leaves upon combined treatment with NaCl and the NPs compared with treatment with NaCl alone. The combined treatment with the NPs and salinity also led to a noticeable increase in the content of Fe and Mn in the shoot. It was concluded that Fe3 O4 NPs can enhance plant growth by improving photosynthetic characteristics, antioxidant balance and the availability of iron and manganese ions, under conditions of soil salinisation.

The biomineralization of silica induced stress tolerance in plants: a case study for aluminum toxicity.

Biomineralization in plant roots refers to the process of cell-induced self-assembly to form nanostructures on the root surface. Silicon (Si) is the second most abundant element in soils, and beneficial to plant growth. Meanwhile, silicon is shown to participate in the process of biomineralization, which is useful for improving mechanical strength and alleviating biotic and abiotic stress, for example silicic acid polymerizes to form amorphous silica (SiO2-nH2O) in the process of growing to resist fungi and environmental stress. This process alters physical and chemical properties of cell wall. However, the mechanistic basis of this process remains unclear. Aluminum toxicity is a major constraint affecting plant performance in acid soil. This paper summarizes recent research advances in the field of plant biomineralization and describes the effects of silicon biomineralization on plant aluminum tolerance and its adaptive significance, using aluminum toxicity as a case study.

Boron supply restores aluminum-blocked auxin transport by the modulation of PIN2 trafficking in the root apical transition zone.

The supply of boron (B) alleviates the toxic effects of aluminum (Al) on root growth; however, the mechanistic basis of this process remains elusive. This study filled this knowledge gap, demonstrating that boron modifies auxin distribution and transport in Al-exposed Arabidopsis roots. In B-deprived roots, treatment with Al induced an increase in auxin content in the root apical meristem zone (MZ) and transition zone (TZ), whereas in the elongation zone (EZ) the auxin content was decreased beyond the level required for adequate growth. These distribution patterns are explained by the fact that basipetal auxin transport from the TZ to the EZ was disrupted by Al-inhibited PIN-FORMED 2 (PIN2) endocytosis. Experiments involving the modulation of protein biosynthesis by cycloheximide (CHX) and transcriptional regulation by cordycepin (COR) demonstrated that the Al-induced increase of PIN2 membrane proteins was dependent upon the inhibition of PIN2 endocytosis, rather than on the transcriptional regulation of the PIN2 gene. Experiments reporting on the profiling of Al3+ and PIN2 proteins revealed that the inhibition of endocytosis of PIN2 proteins was the result of Al-induced limitation of the fluidity of the plasma membrane. The supply of B mediated the turnover of PIN2 endosomes conjugated with indole-3-acetic acid (IAA), and thus restored the Al-induced inhibition of IAA transport through the TZ to the EZ. Overall, the reported results demonstrate that boron supply mediates PIN2 endosome-based auxin transport to alleviate Al toxicity in plant roots.

Integration of Transcriptome and Metabolome Analyses Reveals the Mechanistic Basis for Cadmium Accumulation in Maize.

Cadmium (Cd) pollution in soil has become a major environmental issue worldwide. However, the underlying molecular mechanism of low grain-Cd accumulation (GCA) in maize is still largely unknown. Herein, we report the mechanistic basis for low GCA in maize by a multiomics approach. The low GCA genotype L63 showed normal vacuolar formation and a lower capacity of xylem loading of Cd than the high-accumulator L42 under Cd stress. Transcriptomic sequencing identified 84 low-GCA-associated genes which are mainly involved in the S-adenosylmethionine (SAM) cycle, metal transport, and vacuolar sequestration. A metabolome analysis revealed that L63 plants had a more active SAM cycle and a greater capacity for terpenoid synthesis and phenylalanine metabolism than L42. Combining the analysis of transcriptome and metabolome characterized several genes as key genes involved in the determination of Cd accumulation. Our study identifies a mechanistic basis for low Cd accumulation in maize grains and provides candidate genes for genetic improvement of crops.

The evolution of plant proton pump regulation via the R domain may have facilitated plant terrestrialization.

Plasma membrane (PM) H+-ATPases are the electrogenic proton pumps that export H+ from plant and fungal cells to acidify the surroundings and generate a membrane potential. Plant PM H+-ATPases are equipped with a C­terminal autoinhibitory regulatory (R) domain of about 100 amino acid residues, which could not be identified in the PM H+-ATPases of green algae but appeared fully developed in immediate streptophyte algal predecessors of land plants. To explore the physiological significance of this domain, we created in vivo C-terminal truncations of autoinhibited PM H+­ATPase2 (AHA2), one of the two major isoforms in the land plant Arabidopsis thaliana. As more residues were deleted, the mutant plants became progressively more efficient in proton extrusion, concomitant with increased expansion growth and nutrient uptake. However, as the hyperactivated AHA2 also contributed to stomatal pore opening, which provides an exit pathway for water and an entrance pathway for pests, the mutant plants were more susceptible to biotic and abiotic stresses, pathogen invasion and water loss, respectively. Taken together, our results demonstrate that pump regulation through the R domain is crucial for land plant fitness and by controlling growth and nutrient uptake might have been necessary already for the successful water-to-land transition of plants.

Computational modeling and quantitative physiology reveal central parameters for brassinosteroid-regulated early cell physiological processes linked to elongation growth of the Arabidopsis root.

Brassinosteroids (BR) are key hormonal regulators of plant development. However, whereas the individual components of BR perception and signaling are well characterized experimentally, the question of how they can act and whether they are sufficient to carry out the critical function of cellular elongation remains open. Here, we combined computational modeling with quantitative cell physiology to understand the dynamics of the plasma membrane (PM)-localized BR response pathway during the initiation of cellular responses in the epidermis of the Arabidopsis root tip that are be linked to cell elongation. The model, consisting of ordinary differential equations, comprises the BR-induced hyperpolarization of the PM, the acidification of the apoplast and subsequent cell wall swelling. We demonstrate that the competence of the root epidermal cells for the BR response predominantly depends on the amount and activity of H+-ATPases in the PM. The model further predicts that an influx of cations is required to compensate for the shift of positive charges caused by the apoplastic acidification. A potassium channel was subsequently identified and experimentally characterized, fulfilling this function. Thus, we established the landscape of components and parameters for physiological processes potentially linked to cell elongation, a central process in plant development.

Effects of Cadmium Stress on Root and Root Border Cells of Some Vegetable Species with Different Types of Root Meristem.

Cadmium is one of the most toxic heavy metals and can be easily absorbed by plants, affecting root growth. Root border cells (RBCs), that are located in the periphery of the root cap and originate from the root cap meristem, represent a convenient tool to study the toxic effects of Cd on root performance. In this work, vegetables with contrasting types of root apical meristem (RAM) organizations were used. The open RAM organizations included pea and cucumber, and the closed RAM organizations included tomato, chili, and eggplant. The number of RBCs were significantly higher in the species possessing open RAM organization: pea (11,330 cells per root) > cucumber (8200) > tomato (2480) > eggplant (1830) > chili (1320). The same trend was observed for cell viability: pea (61%) > cucumber (59%) > tomato (49%) > eggplant (44%) > chili (42%). Pea and cucumber had higher relative radicle elongation rates and a lower increase in stress-induced accumulation of malondialdehyde (MDA), making them more resistant to Cd stress than the vegetables with close RAM organization. Under Cd treatment, the number and viability of RBCs in vegetables with both types of RAM organization were significantly decreased. However, the decreasing ratio of the number and viability of RBCs in pea and cucumber was higher than in tomato, chili, and eggplant. Taken together, the plants with the open-type RAM are more tolerant to Cd, and it can be speculated that the cadmium tolerance of the vegetables may be correlated with the number and viability of RBCs in response to cadmium stress.

Effects of Iron Oxide Nanoparticles (Fe3O4) on Growth, Photosynthesis, Antioxidant Activity and Distribution of Mineral Elements in Wheat (Triticum aestivum) Plants.

Engineered nanoparticles (NPs) are considered potential agents for agriculture as fertilizers and growth enhancers. However, their action spectrum differs strongly, depending on the type of NP, its concentrations, and plant species per se, ranging from growth stimulation to toxicity. This work aimed to investigate effects of iron oxide (Fe3O4) NPs on growth, photosynthesis, respiration, antioxidant activity, and leaf mineral content of wheat plants. Wheat seeds were treated with NP for 3 h and plants were grown in the soil at two light intensities, 120 and 300 µmol (photons) m-2·s-1, followed by physiological assessment at several time points. High NP treatment (200 and 500 mg·L-1) enhanced plant growth, photosynthesis and respiration, as well as increasing the content of photosynthetic pigments in leaves. This effect depended on both the light intensity during plant growth and the age of the plants. Regardless of concentration and light intensity, an effect of NPs on the primary photochemical processes was not observed. Seed treatment with NP also led to increased activity of ascorbate peroxidase and reduced malondialdehyde (MDA) content in roots and leaves. Treatment with Fe3O4 also led to noticeable increases in the leaf Fe, P, and K content. It is concluded that iron oxide (Fe3O4)-based NP could enhance plant growth by improving photosynthetic performance and the availability of Fe and P.

Highly efficient removal of cadmium from aqueous solution by ammonium polyphosphate-modified biochar.

Phosphorus-modified biochars are considered as good materials for the removal of heavy metals from wastewater. However, the efficacy of ammonium polyphosphate-modified biochar in cadmium (Cd(II)) adsorption remains largely unknown. In this work, the biochar was respectively modified with ammonium polyphosphate (PABC), phosphoric acid (PHBC) and ammonium dihydrogen phosphate (PNBC) to enhance its adsorption performance for heavy metals from wastewater. The properties of biochar before and after modification and P speciation on the surface of the modified biochar were investigated with FTIR, SEM-EDS, XPS, XRD and 31P NMR, and the adsorption capacity was evaluated by batch adsorption experiments. The results demonstrated that the optimal adsorption performance could be achieved at the solution pH = 4, and the pseudo-second-order and Langmuir models could well describe the Cd(II) adsorption process. The maximum adsorption capacity of PABC, PHBC and PNBC for Cd(II) was 155, 138 and 99 mg g-1, which were 4.84, 4.32 and 3.10 folds that of original biochar, respectively. The 31P NMR showed that orthophosphate accounted for 82.1%, 62.8% and 54.5% of P in PABC, PHBC and PNBC, respectively, which decreased to 28.24%, 33.51% and 29.34% after Cd(II) adsorption, indicating that the orthophosphate ratio in P-modified biochar surface could significantly affect Cd adsorption by forming phosphate precipitate. This work implies that the PABC has greater potential in the removal of Cd from wastewater relative to PHBC and PNBC.

Melatonin as a regulator of plant ionic homeostasis: implications for abiotic stress tolerance.

Melatonin is a highly conserved and ubiquitous molecule that operates upstream of a broad array of receptors in animal systems. Since melatonin was discovered in plants in 1995, hundreds of papers have been published revealing its role in plant growth, development, and adaptive responses to the environment. This paper summarizes the current state of knowledge of melatonin's involvement in regulating plant ion homeostasis and abiotic stress tolerance. The major topics covered here are: (i) melatonin's control of H+-ATPase activity and its implication for plant adaptive responses to various abiotic stresses; (ii) regulation of the reactive oxygen species (ROS)-Ca2+ hub by melatonin and its role in stress signaling; and (iii) melatonin's regulation of ionic homeostasis via hormonal cross-talk. We also show that the properties of the melatonin molecule allow its direct scavenging of ROS, thus preventing negative effects of ROS-induced activation of ion channels. The above 'desensitization' may play a critical role in preventing stress-induced K+ loss from the cytosol as well as maintaining basic levels of cytosolic Ca2+ required for optimal cell operation. Future studies should focus on revealing the molecular identity of transporters that could be directly regulated by melatonin and providing a bioinformatic analysis of evolutionary aspects of melatonin sensing and signaling.

pH-Dependent mitigation of aluminum toxicity in pea (Pisum sativum) roots by boron.

Boron (B) deficiency and aluminum (Al) toxicity are two major constraints on plants grown in acidic soils. B supply mitigates Al toxicity; however, the underlying mechanisms of this process remain elusive. In this work, Pisum sativum plants were used to address this issue. In the absence of pH buffers, B supply had a better mitigation effect on Al-induced root inhibition at pH 4.0 than pH 4.8. However, in MES buffered solution, mitigating effects of B on Al-induced root inhibition were more pronounced at pH 4.8, indicating a strong pH dependency of this process. Quantification of pH-dependent accumulation of Al in various root zones, modification of root pH by an exogenous addition of rapid alkalization factor (RALF), and measuring changes in the rhizosphere pH by fluorescent dyes have revealed operation of two concurrent mechanisms to explain alleviation of the inhibition of root elongation induced by Al toxicity by boron: (1) via enhancing rhizosphere pH under strong acidic stress (pH4.0), and (2) via stabilizing of cell wall by cross-linking with RGII at relatively higher pH (4.8). These findings provide scientific basis and support for the application of B fertilizers in the regions with inherited soil acidity.

The role of NADPH oxidases in regulating leaf gas exchange and ion homeostasis in Arabidopsis plants under cadmium stress.

NADPH oxidase, an enzyme associated with the plasma membrane, constitutes one of the main sources of reactive oxygen species (ROS) which regulate different developmental and adaptive responses in plants. In this work, the involvement of NADPH oxidases in the regulation of photosynthesis and cell ionic homeostasis in response to short cadmium exposure was compared between wild type (WT) and three RBOHs (Respiratory Burst Oxidase Homologues) Arabidopsis mutants (AtrbohC, AtrbohD, and AtrbohF). Plants were grown under hydroponic conditions and supplemented with 50 µM CdCl2 for 24 h. Cadmium treatment differentially affected photosynthesis, stomatal conductance, transpiration, and antioxidative responses in WT and Atrbohs mutants. The loss of function of RBOH isoforms resulted in higher Cd2+ influx, mainly in the elongation zone of roots, which was more evident in AtrbohD and AtrbohF mutants. In the mature zone, the highest Cd2+ influx was observed in rbohC mutant. The lack of functional RBOH isoforms also resulted in altered patterns of net K+ transport across cellular membranes, both in the root epidermis and leaf mesophyll. The analysis of expression of metal transporters by qPCR demonstrated that a loss of functional RBOH isoforms has altered transcript levels for metal NRAMP3, NRAMP6 and IRT1 and the K+ transporters outward-rectifying K+ efflux GORK channel, while RBOHD specifically regulated transcripts for high-affinity K+ transporters KUP8 and HAK5, and IRT1 and RBOHD and F regulated the transcription factors TGA3 and TGA10. It is concluded that RBOH-dependent H2O2 regulation of ion homeostasis and Cd is a highly complex process involving multilevel regulation from transpirational water flow to transcriptional and posttranslational modifications of K/metals transporters.

Cadmium-induced changes in composition and co-metabolism of glycerolipids species in wheat root: Glycerolipidomic and transcriptomic approach.

Lipids are the structural constituents of cell membranes and play crucial roles in plant adaptation to abiotic stresses. The aim of this study was to use glycerolipidomic and transcriptomic to analyze the changes in lipids metabolism induced by cadmium (Cd) exposure in wheat. The results indicated that Cd stress did not decrease the concentrations of monogalactosyldiacyglycerol (MGDG), phosphatidylcholine (PC), lysophosphatidylcholine (LPC) and phosphatidic acid at 6 h, but decreased digalactosyldoacylglycerol (DGDG), MGDG, PC, phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylserine (PS) and LPC concentrations in wheat root at 24 h. Although the concentrations of highly abundant glycerolipids PC and PE were decreased, the ratios of PC/PE increased thus contributing to wheat adaptation to Cd stress. Cd did not reduce the extent of total lipid unsaturation due to the unchanged concentrations of high abundance species of C36:4, C34:2, C34:3 and C36:6 at 6 h, indicative of their roles in resisting Cd stress. The correlation analysis revealed the glycerolipids species experiencing co-metabolism under Cd stress, which is driven by the activated expression of genes related to glycerolipid metabolism, desaturation and oxylipin synthesis. This study gives insights into the changes of glycerolipids induced by Cd and the roles in wheat adaptation to Cd stress.

Nicotiana tabacum as a dead-end trap for adult Diaphorina citri: A potential biological tactic for protecting citrus orchards.

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a key vector of the causal agents of Huanglongbing (HLB), a devastating disease affecting citrus almost worldwide. Nicotiana tabacum L. is an important commercial crop in China. Field observations suggested that D. citri adults die on N. tabacum leaves when grown nearby citrus orchards. In this study, the preference for and survivorship of D. citri adults on N. tabacum and their feeding behavior were investigated. The results showed that D. citri adults were attracted to N. tabacum and to the green leaf volatiles (GLVs) (Z)-3-hexenol and (E)-2-hexenol. The survival of D. citri adults on N. tabacum was less than 30 h, which was shorter than that for adults without food (35 h) and on a suitable host Murraya exotica L. (29 days). Electrical penetration graph (EPG) recordings revealed that the pathway phase of D. citri on N. tabacum leaves consisted of four waveforms-the non-probing phase (NP), the pathway phase (PP, including intercellular probing of activity in the phloem (C) and phloem penetration (D)), phloem salivation (E1), and phloem ingestion (E2). Diaphorina citri only secreted saliva and ingested sap from phloem on N. tabacum leaves and spent the longest duration in phloem sap ingestion (E2). Moreover, L-nicotine, an important defense compound against insects in N. tabacum plants, was highly toxic to D. citri. These results suggested that N. tabacum plants could help to sustainably control the spread of D. citri and HLB when growing in and around citrus orchards.

Cell surface and intracellular auxin signalling for H+ fluxes in root growth.

Growth regulation tailors development in plants to their environment. A prominent example of this is the response to gravity, in which shoots bend up and roots bend down1. This paradox is based on opposite effects of the phytohormone auxin, which promotes cell expansion in shoots while inhibiting it in roots via a yet unknown cellular mechanism2. Here, by combining microfluidics, live imaging, genetic engineering and phosphoproteomics in Arabidopsis thaliana, we advance understanding of how auxin inhibits root growth. We show that auxin activates two distinct, antagonistically acting signalling pathways that converge on rapid regulation of apoplastic pH, a causative determinant of growth. Cell surface-based TRANSMEMBRANE KINASE1 (TMK1) interacts with and mediates phosphorylation and activation of plasma membrane H+-ATPases for apoplast acidification, while intracellular canonical auxin signalling promotes net cellular H+ influx, causing apoplast alkalinization. Simultaneous activation of these two counteracting mechanisms poises roots for rapid, fine-tuned growth modulation in navigating complex soil environments.

Ionomics analysis provides new insights into the co-enrichment of cadmium and zinc in wheat grains.

Cadmium (Cd) is present in many soils and, when enter a food chain, represents a major health threat to humans. The existent large variation in grain Cd content amongst wheat genotypes opens prospects for genetic improvement for reduced Cd uptake in this species. However, selecting low-Cd-accumulating varieties comes with a possible caveat of affecting uptake other essential nutrients. In this work, we screened 134 wheat varieties in 3 various field studies and selected 15 high- and 15 low-Cd accumulating varieties in grains for ionomics analysis. Our results showed that high-Cd accumulating varieties also possessed an ability to accumulate mineral elements of calcium, magnesium, manganese, iron and zinc, while varieties with low Cd content were deficient in many essential nutrients and, especially, zinc (Zn). The above data was confirmed in an independent trail involving another 97 wheat varieties. Thus, selecting plants for high Zn accumulation (as a part of biofortification programs) resulted in an inadvertent increase in accumulation of the toxic Cd in wheat. Vice versa, selecting low Cd-accumulating varieties comes with a danger of reducing their Zn content, with major consequences to food quality and human health. We suggest that the above conundrum can be resolved by understanding the structure-function relations of various transporters isoforms involved in Zn and Cd transport and issue-specific mode of their operation, via cell-based phenotyping followed by molecular breeding.

Optimizing hydroponic culture media and NO3-/NH4+ ratio for improving essential oil compositions of purple coneflower (Echinacea purpurea L.).

Medicinal plants represent a valuable commodity due to beneficial effects of their natural products on human health, prompting a need for finding a way to optimize/increase their production. In this study, a novel growing media with various perlite particle size and its mixture with peat moss was tested for hydroponic-based production of Echinacea purpurea medicinal plant under greenhouse conditions. The plant growth parameters such as plant height, total fresh leave weight, fresh root weight, total biomass, total chlorophyll, leaf area, and essential oil compositions were assessed. Perlite particle size in the growing media was varied from very coarse (more than 2 mm) to very fine (less than 0.5 mm), and the ratio between perlite and peat moss varied from 50:50 v/v to 30:70 v/v. In addition, two nitrate (NO3-) to ammonium (NH4+) ratios (90:10 and 70:30) were tested for each growing media. The medium containing very fine-grade perlite and 50:50 v/v perlite to peat moss ratio was found to be most optimal and beneficial for E. purpurea performance, resulting in maximal plant height, fresh and dry weight, leaf surface area, and chlorophyll content. It was also found that an increase in NO3-/NH4+ ratio caused a significant increase in plant growth parameters and increase the plant essential oil content. The major terpene hydrocarbons found in extract of E. purpurea with the best growth parameters were germacrene D (51%), myrcene (15%), α-pinene (12%), ß-caryophyllene (11%), and 1-Pentadecene (4.4%), respectively. The percentages of these terpene hydrocarbons were increased by increasing of NO3-/NH4+ ratio. It can be concluded that decreasing the perlite particle size and increasing the NO3-/NH4+ ratio increased the plant growth parameters and essential oil compositions in E. purpurea.