Effective phytoremediation depends on plant species that combine high biomass production with efficient P accumulation and tolerance to elevated nutrient loads. Therefore, this study aimed to compare the P removal efficiency (PRE), uptake capacity, and toxicity threshold among four Azolla samples from three species (A. pinnata, A. caroliniana, and A. filiculoides) grown under in high-P media. Growth responses, P, Fe, N, and Zn content, and PRE were measured. All species showed similar growth and P uptake responses up to 5 mM P. Beyond this concentration, species-specific responses were observed: A. pinnata became toxic and died while A. filiculoides (Utr.) tolerated up to 25 mM. In contrast, A. caroliniana and A. filiculoides (Can) maintained stable growth even under higher P exposure conditions, despite no further increase in tissue P concentration. This pattern suggests a regulated response to P accumulation, rather than dilution or luxury consumption (nutrient uptake and accumulation beyond required levels without further increase in biomass). P removal efficiency decreased significantly at concentrations above 5 mM and remained unchanged at higher P supplies, indicating that the contaminant concentration significantly affects the removal efficiency. Overall, the results indicate significant inter- and intra-specific variation in P toxicity, uptake and removal in Azolla. Therefore, this highlights the importance of selecting the appropriate species and considering contaminant concentration for efficient phytoremediation.

Glycyrrhiza glabra L., belonging to the Fabaceae family, is an important source of pharmacologically active compounds, especially glycyrrhizin. Hairy root culture is an efficient approach for the stable biosynthesis of secondary metabolites. In this study, three experimental sets were performed to optimize hairy root establishment. Initially, the effect of explant type and Agrobacterium rhizogenes strain on the effectiveness of hairy root induction was evaluated. The maximum transformation frequency (86 Not applicable.

Wheat streak mosaic disease, caused by wheat streak mosaic virus (WSMV), is considered a serious cereal disease that threatens wheat yield worldwide. To date, only a limited number of genes related to WSMV resistance have been characterized. Identification of novel sources of resistance is essential for the development of resistant varieties. In this study a genome-wide association study (GWAS) and expression analysis of candidate QTLs through RT-qPCR were implemented on a set of 175 globally diverse wheat genotypes. A GWAS of 21,773 high-quality DArTseq markers revealed 17 significant markers (p-value < 10− 4, and FDR < 0.05) on chromosomes 1B, 2 A, 2B, 2D, 3 A, 3B, 4B, 5 A, 5B, 6 A, 6B, 6D and 7 A. GWAS results revealed some potential candidate genes for WSMV resistance, including several nucleotide binding site-leucine-rich repeats (NBS-LRR)-type resistance genes, different types of kinases such as serine-threonine/tyrosine-protein kinase and defense-related proteins such as F-box proteins (FBPs), GroEL-like heat shock protein 60 and cytochrome P450. Moreover, comparisons of the expression profiles of eight candidate genes between two accession, resistant (the landrace IPK41079) and susceptible (the cultivar Alamut), using RT-qPCR revealed higher relative expression levels in resistant than susceptible accessions. These candidate genes and associated QTLs represent promising targets for marker-assisted selection (MAS) following independent validation in additional wheat populations and field environments.

Milk thistle (Silybum marianum), a medicinal plant from the Asteraceae family, is widely known for its high-value secondary metabolite, silymarin, a flavonolignan with potent hepatoprotective and antioxidant properties. This study aimed to enhance silymarin production by eliciting cell suspension cultures with methyl jasmonate (MeJA) and salicylic acid (SA). Initially, callus induction was optimized using leaf explants treated with kinetin, 2,4-Dichlorophenoxyacetic acid (2,4-D), and picloram, achieving maximum proliferation with 0.8 mg/L kinetin, 0.1 mg/L 2,4-D, and 2 mg/L picloram. Subsequent elicitation of suspension cultures revealed that 0.05 mM MeJA and 0.25 mM SA resulted in the highest silymarin accumulation, as confirmed by High-performance liquid chromatography (HPLC) analysis. Additionally, quantitative polymerase chain reaction-based gene expression profiling demonstrated that MeJA and SA differentially regulated the transcription of Phenylalanine ammonia-lyase (PAL), Cinnamyl Alcohol Dehydrogenase (CAD), and Chalcone Isomerase (CHI), key genes involved in the phenylpropanoid pathway, with distinct temporal expression patterns. These findings underscore the efficacy of MeJA and SA as potent elicitors for enhancing silymarin biosynthesis, offering a promising biotechnological strategy for optimizing secondary metabolite production in medicinal plants.

Kelussia odoratissima Mozaff (celery) is a valuable endemic spice and aromatic plant of the Apiaceae family, rich in secondary metabolites. This study aimed to optimize in vitro regeneration methods and LEDs to enhance the phenolic compounds and chemical composition of Kelussia. Various combinations and concentrations of plant growth regulators (PGRs) were tested using three types of explants: cotyledons, hypocotyls, and zygotic embryos. In the second part of the study, five light treatments were tested: viz. red, blue, red‒blue, white, and control. Secondary volatile oil compounds were analyzed using solid‒phase microextraction (SPME) arrow to assess changes under each light condition. HPLC analysis identified the principal phenolic and flavonoid compounds in the different explants, such as caffeic acid, chlorogenic acid, and rutin. In particular, the highest concentration of phenolic compounds (caffeic acid: 43.09 µg/g) was detected in zygotic embryo explants treated with 2–4-D at 0.5 mg/L and BAP at 0.25 mg/L. The SPME analysis revealed that (E)-farnesene (32.09

Rhynchosporium commune is a fungal pathogen responsible for causing scald disease in barley, leading to significant yield losses and reduced grain quality in susceptible cultivars. Effector proteins secreted by R. commune play crucial roles in manipulating host defenses and facilitating infection. Hence, this study aimed to identify and characterize effector candidates (ECs) in R. commune using a comprehensive bioinformatics approach combined with experimental validation. Initially, a dataset of 12,211 genes from the R. commune strain UK7 genome was analyzed to identify potential ECs, resulting in the selection of 48 candidate proteins. These candidates were further validated using RNA-Seq analysis, which confirmed significant expression of 27 ECs during infection. Our analysis re-identified key effectors, including CZT06923 and CZT13833, with 100% identity to NIP3 and NIP2, respectively, in R. commune. Novel ECs, such as CZT07600, CZT13755, and CZT13375, were identified with lower identity to NIP2, suggesting potential variants. Additionally, structural analysis revealed that CZT07873 EC indicates significant structural similarity to known fungal effector. qRT-PCR validation confirmed the differential expression of CZS93219 and CZT13755, with peak expression at 9 and 12 dpi, respectively. This comprehensive approach enhances our understanding of R. commune's pathogenic mechanisms and provides insights into potential targets for developing disease management strategies in barley cultivation.

In this study, two cultivars of strawberry (Fragaria × ananassa Duch.) were compared for their response to different levels of heat stress (30, 35, and 40 °C, categorized as mild, moderate, and severe heat stress, respectively) with controls growing at 25 °C. At temperatures of 25 °C and mild heat stress, there were no obvious differences in symptoms between the cultivars Camarosa and Kurdistan. At 40 °C, Camarosa exhibited more severe damage compared to Kurdistan, indicating that Kurdistan had greater heat stress tolerance. No significant difference in γ-aminobutyric acid (GABA) content was observed in Camarosa until 35 °C, where GABA content significantly decreased compared to the control. In contrast, GABA levels in Kurdistan steadily increased as the heat stress intensified from 25 to 40 °C. The concentration of total soluble sugars (TSS) and activities of catalase, ascorbate peroxidase, and superoxide dismutase in both cultivars initially increased under heat stress but declined at 40 °C in Camarosa. In Kurdistan, elevated temperatures triggered the expression of GABA shunt-related genes, including glutamate decarboxylase (GAD1) and two catabolic enzymes (GABA-T1, GABA-T3, and SSADH), suggesting that under heat stress, GABA and succinate act as temporary storage metabolites to supply the tricarboxylic acid cycle when the stress is mitigated.

Heavy metal contamination in aquatic ecosystems poses serious environmental and health risks. Azolla caroliniana, a promising candidate for phytoremediation, has the potential to absorb heavy metals like lead (Pb). However, limited information is available on the enzymatic and genetic responses of A. caroliniana under Pb stress. This study investigates the plant's phytoremediation capacity by analyzing antioxidant enzyme activity and gene expression under lead (II) acetate [Pb(C2H3O2)2] concentrations (0, 500, 750, 1,000 µM) over three time points (days 2, 4, and 6). The results showed that with increasing Pb concentration, antioxidant enzyme activity increased. Chlorophyll content increased by 25% at 1,000 µM Pb, whereas carotenoid and anthocyanin levels decreased by 233% and 30%, respectively. Total protein content declined by 90%. Additionally, SOD and CAT activities increased by 28%, while APX activity rose by 25%. Gene expression analysis revealed that genes associated with antioxidant enzymes CAT (94% decrease), APX (64% decrease), SOD (40% decrease), GR (8% increase), and PPO (93% decrease) as well as anthocyanin biosynthesis genes C4H (56% decrease) and CHS (87% decrease) were significantly downregulated at the highest Pb concentration in the later stages, indicating a critical adaptation phase. Observed gene expression fluctuations in the later stages may result from A. caroliniana's dynamic stress response, where initial upregulation of antioxidant defense genes suggests an attempt to mitigate oxidative stress, followed by metabolic adjustments leading to variations in gene expression levels. Lead uptake peaked on day 2 but significantly declined by 42% on day 6, likely due to cellular saturation, activation of detoxification mechanisms, or lead translocation into the growth medium. These findings highlight the potential of A. caroliniana as an effective phytoremediator for Pb-contaminated water bodies.

As the world's most valuable spice, saffron holds significant economic importance in Iran. Rhizoglyphus robini Claparede (Acari: Astigmata: Acaridae) is one of the most critical and damaging pests affecting corm plants globally, including saffron fields in Iran. The repeated use of acaricides has led to the development of resistance in pest populations. Bacterial communities play a crucial role in the various physiological processes of their insect hosts, including the metabolism involved in detoxification. Bioassays against R. robini were performed with two acaricides, abamectin, and propargite, using a filter paper method. Based on the results, the LC50 values of 2.3 and 25 mg a.i./L were estimated for abamectin and propargite, respectively. The impact of antibiotic pretreatment on acaricide toxicity was assessed using six antibiotics: tetracycline, azithromycin, penicillin, cefalexin, cefixime, and streptomycin. The antibiotics (1.5 mL of 100 mg/L) were added to Petri dishes with a layer of filter paper. Mortality was significantly increased in the tetracycline pretreatment group, whereas the other antibiotics showed negligible effects. A bioassay comparing tetracycline pretreatment with a mixture of the other five antibiotics revealed that the antibiotic mixture also significantly enhanced toxicity. Pretreatment with the antibiotic mixture led to a 5.6-fold increase in abamectin toxicity and a 10.2-fold increase in propargite toxicity. To estimate the density of bacterial community in different treatments, total DNA was extracted, and 16S rRNA gene amplification was performed using a general bacterial primer pair. The semiquantitative PCR results indicated reduced bacterial density in mites treated with tetracycline or an antibiotic mixture compared with the control. Enzymatic assays showed that the activities of detoxification enzymes, including glutathione S-transferases, carboxyl/cholinesterases, and cytochrome P450 monooxygenases, were significantly reduced in mites pretreated with tetracycline or antibiotic mixture. These findings suggest that bacterial community may influence acaricide metabolism by modulating detoxification enzyme activities in their hosts. This study provides a basis for further research into the mechanisms of symbiont-mediated detoxification in pest management.

Greenhouses located at high latitudes and in cloudy areas often experience a low quality and quantity of light, especially during autumn and winter. This low daily light integral (DLI) reduces production rate, quality, and nutritional value of many crops. This study was conducted on Sakhiya RZ F1 tomato plants to evaluate the impact of LED lights on the growth and nutritional value of tomatoes in a greenhouse with low daily light due to cloudy weather. The treatments included LED growth lights in three modes: top lighting, intra-canopy lighting, and combined top and intra-canopy lighting. The results showed that although the combined top and intra-canopy lighting reached the maximum increase in tomato yield, exposure to intra-canopy LED lighting alone outperformed in tomato fruit yield increase (28.46%) than exposure to top LED lighting alone (12.12%) when compared to no supplemental lighting during the entire production year. Intra-canopy exposure demonstrated the highest increase in tomato lycopene (31.3%), while top and intra-canopy lighting exhibited the highest increase in vitamin C content (123.4%) compared to the control. The LED light treatment also had a very positive effect on the expression of genes responsible for metabolic cycles, including Psy1, LCY-β, and VTC2 genes, which had collinearity with the increase in tomato fruit production.

Glycyrrhizin is a valuable secondary metabolite with high medicinal properties, which is known as the most important compound in the licorice (Glycyrrhiza glabra L.). Considering the problems in growing plants in the field, the use of tissue culture techniques, especially hairy root culture, makes the production of glycyrrhizin simpler and more affordable. The influence of Agrobacterium rhizogenes strains on the efficiency of hairy root induction showed that the highest hairy roots were observed using MSU strain (80%). Also, the effect of explant type (leaf, stem and petiole) and age (two-week-old, three-week-old and four-week-old), light conditions (24 hours of darkness and 16 hours of light-8 hours of darkness) and carbohydrate source (3% glucose and 3% sucrose) showed that the production of hairy roots from this medicinal plant depends on the type and age of explant, light treatment and the composition of the culture medium and the highest hairy roots induction was observed in leaf explant (80%), three-week-old leaf (76.66%) and MS medium containing 3% sucrose (86.66%) and treatment of 24 hours of darkness (86.66%). The amount of glycyrrhizin in hairy root lines treated by 100 µM methyl jasmonate (MJA) after 24 hours increased in the no cutting treated line and decreased in the cutting treated lines compared to the control line. In conclusion, elicitation of G. glabra hairy root culture is a suitable platform for achieving high glycyrrhizin yields.

In this research, a HPLC analysis, along with transcriptomics tools, was applied to evaluate chitosan and water stress for the prediction of phenolic flavonoids patterns and terpenoid components accumulation in Salvia abrotanoides Karel and S. yangii. The results indicated that the tanshinone contents under drought stress conditions increased 4.2-fold with increasing drought stress intensity in both species. The rosmarinic acid content in the leaves varied from 0.038 to 11.43 mg/g DW. In addition, the flavonoid content was increased (1.8 and 1.4-fold) under mild water deficit conditions with a moderate concentration of chitosan (100 mg L−1). The application of foliar chitosan at 100 and 200 mg L−1 under well-watered and mild stress conditions led to increases in hydroxyl cryptotanshinone (OH-CT) and cryptotanshinone (CT) contents as the major terpenoid components in both species. The expressions of the studied genes (DXS2, HMGR, KSL, 4CL, and TAT) were also noticeably induced by water deficit and variably modulated by the treatment with chitosan. According to our findings, both the drought stress and the application of foliar chitosan altered the expression levels of certain genes. Specifically, we observed changes in the expression levels of DXS and HMGR, which are upstream genes in the MEP and MVA pathways, respectively. Additionally, the expression level of KSL, a downstream gene involved in diterpenoid synthesis, was also affected. Finally, the present investigation confirmed that chitosan treatments and water stress were affected in both the methylerythritol phosphate pathway (MEP) and mevalonate (MVA) pathways, but their commitment to the production of other isoprenoids has to be considered and discussed.

Improving flower yield through lengthening flowering duration is a primary breeding objective in saffron (Crocus sativus L.). Asexual reproduction in saffron limits biodiversity and conventional breeding. Hence, eliciting flowering-related gene expression by plant growth regulators is one way to achieve this aim. The phytohormones methyl jasmonate (MeJA) and 6-benzyl amino purine (BAP) signals are received by the MADs-box gene family. In this study, to elucidate the role of phytohormones on flower development, plant were treated with BAP (0 and 5 mg L−1), and methyl jasmonate (MeJA) (0, 20, and 100 mM) at three developmental stages of the saffron life cycle. Then, the expression of the SHORT VEGETATIVE PHASE (CsSVP) gene as a MADS-box gene family was assessed in the saffron corm. The activities of antioxidant enzymes, soluble sugar, starch content, and soluble protein content were also measured in corm, leaf, and root tissues. The application of MeJA and BAP treatments resulted in down-regulation of CsSVP expression in the corm during dormancy. At the dormancy stage, catalase, peroxidase activity decreased, and ascorbate peroxidase activity increased following MeJA treatment. In contrast, an increment in catalase and peroxidase activity and reduction of ascorbate peroxidase activity were observed after treatment with MeJA during the flowering stage. This change in enzyme activity is most likely due to flowering, which demands the re-allocation of resources. As flowering is a process heavily influenced by the environment, plants treated with MeJA, which may mimic environmental stress, showed changes in antioxidant enzyme activity. Overall, these results suggested that MeJA and BAP treatments play a significant role in the vegetative-to-reproductive phase change in saffron.

Perovskia species are considered as valuable ornamental plants. In the present study, the enzymatic and non-enzymatic antioxidants were evaluated in P. atriplicifolia, and P. abrotanoides in response to water deficit stress. The root harvesting was performed after 0, 3, 5, 7, and 9 days exposure to stress. In both species, total phenolics content, total flavonoids, enzymatic antioxidant activities, total tanshinones, tanshinone IIA, cryptotanshinone, hydroxy-cryptotanshinone, and proline substantially increased with the severity of stress. In the current study, the variations in tanshinone profile and the expression of genes (DXS1, HMGR, KSL) related to tanshinones biosynthesis were also investigated. The results revealed the negative trend between the concentration of malondialdehyde, and hydrogen peroxide as well as the harmonized augmentation in activities of enzymatic antioxidants including guaiacol peroxidase, and ascorbate peroxidase, exclusively on 7th day of stress. The expression ratios of all studied genes were markedly induced by the drought stress. The content of major oxidative stress-related indicators suggested that P. atriplicifolia should be better pre-adapted to water deficit physiological tolerance than P. abrotanoides. Finally, the experimental results can provide further insight into differential responses to imposed water-limited stress along with choice of the optimal eustress treatment to obtain the desired composition of pharmacologically useful diterpenoids.

Several Salvia species are among the most valuable aromatic herbs used for industrial and pharmaceutical applications. Hence, under greenhouse trial conditions, the effects of chitosan treatment (0, 100, and 200 mg L-1) and water deficiency stress on the morphological, physiological, and biochemical features of two Salvia species were examined. Significant changes were seen in chlorophyll a, root volume, dry and fresh weight, and H2O2 concentration as a result of drought stress. Significant influence of chitosan was found for all studied parameters except root length and malondialdehyde (MDA) content. Hydrogen peroxide (H2O2), proline, and MDA were elevated, while photosynthetic pigments decreased under drought stress. The highest essential oil (EO) content (2.20% d.b.) was recorded under moderate stress condition in the absence of chitosan treatment. Using chitosan topically, it is possible to offset the impact of water scarcity on EO content decline and enhance EO compositions. The compensatory effects of chitosan application under stress conditions were observed on the abundance of EO constituents, such as 1,8-cineol, camphor, bornyl acetate, alpha-bisabolol, alpha-cadinol, and alpha-humulene. Moreover, present results suggested that chitosan application can alleviate the drought damage in studied Salvia species.

Lime is an important commercial product in tropical and subtropical regions, where drought stress is becoming one of the most severe environmental challenges in the agricultural sector. Melatonin is an antioxidant molecule that helps plants regulate their development and respond to a variety of stresses. In this research, the effects of exogenous melatonin treatments were evaluated at different concentrations (0, 50, 100, and 150 μM) on biochemical aspects and gene expression in two species of lime plants ("Mexican lime" and "Persian lime") under normal (100% field capacity (FC)) and drought stress conditions (75% and 40% FC). The experiments were factorial and based on a completely randomized design (CRD) with four replicates. Drought stress caused electrolyte leakage (EL) as well as accumulations of hydrogen peroxide (H2O2) and malondialdehyde (MDA), indicating the occurrence of damage to cellular membranes. In contrast, the melatonin pretreatment at various concentrations reduced the levels of EL, H2O2 and MDA while mitigating the negative effects of drought stress on the two lime species. The application of melatonin (100-μM) significantly increased the level of proline content and activity of antioxidant enzymes in plants under drought stress compared to control plants. According to real-time PCR analysis, drought stress and melatonin treatment enhanced the expression of genes involved in ROS scavenging, proline biosynthesis, and cell redox regulation in both species, as compared to their respective controls. According to these findings, melatonin is able to detoxify ROS and regulate antioxidant systems, thereby protecting lime plants from drought stress-induced damages.

Quince is known as an iron (Fe)-deficiency sensitive fruit tree, showing chlorosis symptoms when grown in calcareous soils. Arbuscular mycorrhizal (AM) fungi occurring widely in soils are able to increase plant growth and mineral uptake. An experiment was conducted to examine whether inoculation with AM fungi species would enhance Fe uptake in quince seedlings. The greenhouse experiment was arranged as a factorial experiment with two factors, including three AM fungi inoculation regimes (non-AM, Funneliformis mosseae, and Rhizophagus intraradices) and two Fe levels (50 mu M representing Fe-sufficiency and 5 mu M as Fe-deficiency). Fe-deficiency reduced biomass, chlorophyll concentration, and the chlorophyll fluorescence (F-v/F-m) ratio, but increased root colonization. Inoculation of seedlings with AM fungi, especially R. intraradices, led to significant enhancements in shoot and root dry weights, leaf chlorophyll content, and leaf F-v/F-m ratio in Fe-deficient quince when compared with the non-AM control. Under Fe-deficiency, AM-inoculated seedlings, compared to the non-AM plants, exhibited a higher root phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) activity and a greater root PAL1 gene expression. A similar result was noted for root phenolic compounds. AM colonization significantly promoted root and shoot Fe concentrations compared with the non-AM plants, in parallel with the increase in ferric chelate reductase (FCR, EC 1.16.1.7) enzyme activity and up-regulate FRO2 gene expression, under Fe-deficiency. These results suggest that enhancements in the phenolic compound content and, as well as PAL and FCR activities along with their co-regulation at transcriptional levels, could play key roles in AM-mediated mitigation of Fe stress in quince seedlings.

An experiment was conducted to examine whether application of sodium nitroprusside (SNP), a donor of NO, can improve thermo-tolerance of strawberry (Fragaria x ananassa) plants through inducing antioxidant system, and up-regulating heat stress transcription factors (HSFs) and heat shock proteins (HSPs) genes. Ventana strawberry plants were exposed to various temperatures (25, 35, and 40 degrees C) for 24 h after pre-treatment with 0, 50, and 100 mu M SNP. Heat stress significantly induced malondialdehyde and hydrogen peroxide (H2O2) contents, and increased accumulation of proline, whereas reduced relative water content (RWC), leaf chlorophyll fluorescence, and carotenoid content. In addition, heat stress enhanced superoxide dismutase and guaiacol peroxidase activities, increased glutathione and ascorbic acid contents, and reduced catalase and ascorbate peroxidase activities. Pre-treatment with SNP, especially at 100 mu M, ameliorated heat injury by controlling the overaccumulation of H2O2, reducing lipid peroxidation, improvement of RWC, and increasing the enzymatic and non-enzymatic antioxidants. Transcriptomic profiling analysis showed that the expression of FaTHSFA2a, FaTHSFB1a, HSP70, and HSP90 in SNP pre-treated plants was significantly higher than non-treated plants after 2 h of heat stress at 40 degrees C. These results suggested that NO alleviates heat-induced oxidative damage by modulating antioxidant pathways and fast inducing the expression of heat-stress related genes.

Purpose: Modern onion breeding is almost completely based on the production of hybrid seed. This project was performed to evaluate the effectiveness of marker-assisted selection (MAS) in identification of the cytoplasmic types and Ms locus in 123 onion accessions. Research method: Three cytoplasmic markers cob, accD and MK were used to identify the sterility (S) from the fertility (N) cytoplasm and four nuclear molecular markers (OPT, PsaO, Jnurf-13 and AcSKP1) were used for genotyping of Ms alleles. Findings: The results showed that the two accD and cob markers were quite similar in the detection of the type of cytoplasm with 100% male sterility for male sterile lines and 100% fertility for maintainer lines. The MK marker was able to distinguish T-type cytoplasm as well. Based on the results, the frequency of fertility (N) was much more than the frequency of sterility (S and T) cytoplasm found to be 90% in Dorche (pop.1), 100% in Dorche (pop.2) and Kashan based on marker cob and accD and with MK marker, was found to be 80%, 90% and 82% in Dorche (pop.1), Dorche (pop.2) and Kashan, respectively. Limitations: In this study, nuclear markers were not successful due to not finding linkage disequilibrium with the Ms locus, suggested more markers to be evaluated. Originality/Value: Molecuar markers were very suitable for the indentification of S or N lines. Cytotype (N/S) determination of plants by usingmolecular markers (cob, accD and MK), could easily reduce the population size required for the production of onion hybrid seeds.

Melatonin is a signaling molecule that is involved in inducing plantsʼ abiotic stress tolerance. To determine the possible effects of the melatonin pre-treatment on thermotolerance in strawberry (Fragaria × ananassa Duch.), the heat-sensitive cultivar Ventana was subjected to high temperatures (35 °C and 40 °C) for 10 h after pre-treatment with 0, 50, and 100 μM melatonin. High temperature increased malondialdehyde and H2O2 contents and reduced relative water content, carotenoid content, and catalase and ascorbate peroxidase activities, which led to a marked reduction in chlorophyll fluorescence. However, pre-treatment with melatonin at 100 μM decreased heat injury symptoms and induced antioxidant mechanisms in heat-sensitive cultivar Ventana, increasing heat tolerance. The results showed that when the melatonin pre-treated strawberry plants were exposed to high temperature (40 °C) for 2 h, the levels of FaTHsfA2a and HSP90 mRNA significantly increased, but after heat treating at 40 °C for 5 and 10 h, their mRNA levels were as similar as the control. The results support the hypothesis that melatonin acts as an important signaling molecule during heat stress to induce protective mechanisms via up-regulating the expression of defense HSF (FaTHsfA2a, FaTHSFB1a) and HSP (HSP90) genes.