Type Of Elicitor Research Articles

Responses to exogenous elicitor treatment in lead-stressed Oryza sativa L.

Heavy metal toxicity adversely affects plants by changing physiological, biochemical, and molecular mechanisms. Lead (Pb) is one of the most common heavy metal pollutants. Hence this study investigated changes caused by exogenous methyl jasmonate (MeJA; 20 and 100 µM) and salicylic acid (SA; 2 and 20 mM) elicitors in local Karacadağ rice exposed to Pb stress (0, 100, and 400 ppm). The effects of elicitors on photosynthetic pigment content (chlorophyll a, chlorophyll b, and total carotenoid), proline, malondialdehyde (MDA), total phenolic and flavonoid, Pb, and total protein contents in stressed plants were evaluated. All parameters studied increased and decreased at varying rates in the treatment groups compared to the Pb-free group (control), indicating that rice plants were affected by Pb stress. The elicitors (MeJA, SA, and MeJA + SA) were applied by foliar spraying. The elicitor treatments increased photosynthetic pigment content, total protein, proline, total flavonoid, and phenolic contents depending on the elicitor type and concentration. MDA and Pb contents, increasing with Pb toxicity, decreased with elicitor treatments, and the stress degree was reduced. When the elicitors were compared, SA was more effective than MeJA in total flavonoid content at 400 ppm Pb toxicity. However, MeJA was more effective in photosynthetic pigment contents, MDA, total protein, Pb, total phenolic, and proline contents. The best results for all parameters examined in rice plants exposed to Pb toxicity were obtained from the 400 ppm Pb + 2 mM SA + 20 µM MeJA treatment group. In conclusion, this study showed that the combined application of MeJA + SA alleviated the harmful effects of Pb by reducing MDA and increasing photosynthetic pigments, total protein, proline, and secondary metabolites, especially at high Pb concentrations. Consequently, this study demonstrated that the combined use of MeJA and SA in rice plants eliminated the negative effects of stress quite effectively, even at high Pb concentrations. Therefore, future studies should focus on the synergistic application of different elicitors to better understand the effects of heavy metal toxicity on plant growth and development.

Associations between the medial olivocochlear reflex, middle-ear muscle reflex, and sentence-in-noise recognition using steady and pulsed noise elicitors

The middle-ear muscle reflex (MEMR) and medial olivocochlear reflex (MOCR) modify peripheral auditory function, which may reduce masking and improve speech-in-noise (SIN) recognition. Previous work and our pilot data suggest that the two reflexes respond differently to static versus dynamic noise elicitors. However, little is known about how the two reflexes work in tandem to contribute to SIN recognition. We hypothesized that SIN recognition would be significantly correlated with the strength of the MEMR and with the strength of the MOCR. Additionally, we hypothesized that SIN recognition would be best when both reflexes were activated. A total of 43 healthy, normal-hearing adults met the inclusion/exclusion criteria (35 females, age range: 19–29 years). MEMR strength was assessed using wideband absorbance. MOCR strength was assessed using transient-evoked otoacoustic emissions. SIN recognition was assessed using a modified version of the QuickSIN. All measurements were made with and without two types of contralateral noise elicitors (steady and pulsed) at two levels (50 and 65 dB SPL). Steady noise was used to primarily elicit the MOCR and pulsed noise was used to elicit both reflexes. Two baseline conditions without a contralateral elicitor were also obtained. Results revealed differences in how the MEMR and MOCR responded to elicitor type and level. Contrary to hypotheses, SIN recognition was not significantly improved in the presence of any contralateral elicitors relative to the baseline conditions. Additionally, there were no significant correlations between MEMR strength and SIN recognition, or between MOCR strength and SIN recognition. MEMR and MOCR strength were significantly correlated for pulsed noise elicitors but not steady noise elicitors. Results suggest no association between SIN recognition and the MEMR or MOCR, at least as measured and analyzed in this study. SIN recognition may have been influenced by factors not accounted for in this study, such as contextual cues, warranting further study.

Enhancement of Plumbagin Production through Elicitation in In Vitro-Regenerated Shoots of Plumbago indica L.

Plumbago indica L. contains a valuable bioactive compound called plumbagin. Elicited regenerated shoots grown in vitro could be another source of high-yielding plumbagin. The purpose of this investigation was to examine the effects of elicitor type and concentration, as well as elicitation period, on plumbagin content in in vitro-regenerated shoots of P. indica. Nodal explants were cultured on Murashige and Skoog (MS) medium containing 1 mg/L benzyladenine (BA) in combination with 0-150 mg/L yeast extract or 50-150 µM salicylic acid for four weeks. Plumbagin levels of 3.88 ± 0.38% and 3.81 ± 0.37% w/w g dry extract were achieved from the 50 and 100 mg/L yeast extract-elicited shoots, which were higher than the value obtained for the control. However, the addition of salicylic acid did not increase the plumbagin content. In the elicitation period experiment, nodal explants were cultured on MS medium supplemented with 1 mg/L BA and 50 mg/L yeast extract for durations of three, four and five weeks. The 4-week yeast extract-elicited shoot had a maximum plumbagin content of 3.22 ± 0.12% w/w g dry extract, greater than that of the control. In summary, the plumbagin content of the in vitro P. indica shoots was enhanced by 4-week elicitation using 50 mg/L yeast extract.

El ADN extracelular: un elicitor novedoso en la agricultura

Plants, being sessile organisms, use the recognition of molecules called elicitors to act in different stress situations. These elicitors are a diverse group of molecules of biogenic origin that include proteins, polysaccharides, and lipopolysaccharides, among others. These molecules are capable of modifying physiological, metabolic, and genetic responses to achieve an appropriate response to events that cause a cellular imbalance such as physical damage, infections, or other alterations. Extracellular DNA (eDNA) has been recognized as a relevant plant elicitor in recent years due to the effect caused when it is applied in different doses, so its study has become a priority issue. For this reason, this work includes an overview of the different types of elicitors used in the agricultural industry, emphasizing studies that include eDNA as a plant elicitor. In addition, a perspective of using eDNA as a possible elicitor of beneficial microorganisms is included, which generates new research areas that will benefit the development of this technology.

Quantitative Measurement of Pattern-Triggered ROS Burst as an Early Immune Response in Tomato.

The rapid accumulation of extracellular "reactive oxygen species" (ROS), also known as the "oxidative burst", is an early plant immune response triggered by pathogen-derived microbe-associated molecular patterns and by endogenous plant signaling molecules. The oxidative burst is often used as a readout for the activation of defense signaling. Here, we present a detailed protocol for the continuous measurement of ROS production in leaf discs of tomato plants, using a chemiluminescence-based assay in a microtiter plate format. We also include recommendations for data analysis and for the quantitative assessment of differences in ROS burst dynamics, as caused by different types of elicitors, or in different tomato genotypes.

Application of chitosan lactate, selenite, and salicylic acid as an approach to induce biological responses and enhance secondary metabolism in Melissa officinalis L.

Given the beneficial aspects of elicitation, plant elicitors are being extensively used in recent years to increase the production of desired secondary metabolites in vitro. However, the potential of elicitors to be used in vivo is still limited due to the insufficient knowledge of their biological activity and the dependence on a number of factors, especially the elicitor type and the duration of the elicitation. For this reason, further in vivo studies are still needed to unravel the biological basis of the elicitation process. Therefore, the aim of the study was to compare the effect of three chemically different substances (150 mg/L chitosan lactate, ChL; 10 mg/L selenium as selenite, Se; 100 mg/L salicylic acid, SA; a mixture of ChL+Se+SA in the proportion of 1:1:1) on some aspects of primary and secondary metabolism in Melissa officinalis L. The main objective of the research was to determine the potential of these foliar-applied compounds in the elicitation of phenolic metabolites in vivo. The strongest elicitation effect was found after the use of ChL and SA, and a slightly weaker effect was noted after the application of Se; in turn, the mixture of the elicitors generally did not cause changes in the level of phenolic metabolites. Moreover, regardless of the elicitor type, their highest concentrations were recorded on the 8th day of elicitation, while no significant increase was generally observed on the 4th day. Among the analyzed metabolites, rosmarinic acid hexoside was most strongly induced by the elicitation, and its level increased even several times compared with the control. A very effective increase in the accumulation of rosmarinic and lithosperimic acids was detected as well. The elicitors also increased the antioxidant activity of the plant extracts. No visual signs of toxicity of these compounds or their effect on plant biomass were found, although there were some elicitor-induced changes in parameters related to oxidative stress (increase in H2O2 and O2-˙ accumulation and lipid peroxidation) and photosynthesis (reduction of chlorophyll fluorescence indicators and photosynthetic pigment concentrations). We recommend that ChL or SA alone should be applied for effective and successful elicitation of intact lemon balm in controlled pot cultivation. This method can be an easy and cost-effective alternative to in vitro, suspension, or hydroponic cultures of M. officinalis and can be widely used for acquisition of high-quality plant raw material with improved nutraceutical and pro-health values.

Epigenetics: an innovative lever for grapevine breeding in times of climatic changes

Climate change imposes numerous threats to viticulture. Different strategies have been developed to mitigate these effects that range from innovative vineyard management methods and precision viticulture to the breeding of new varieties and rootstocks better adapted to environmental challenges. Epigenetics refer to heritable changes in genome functioning that are not mediated by DNA sequence variations. The recent discovery that epigenetic memories can mediate acclimation and adaptation of plants to their environment now provides new levers for plant improvement facing climate changes without significant impact on the genetic information. This can be mediated either by using the epigenetic memories of stresses and/or by creating epigenetic diversity in the form of new epialleles without changing the genetic information. Indeed, grapevine is a perennial grafted clonally propagated plant, and as such, presents epigenetic specificities. These specificities require adapting strategies that have already been developed in model plants but also offer opportunities to explore how epigenetic memories and diversity can be a major source of rapid adaptation to the environment for plants bearing similar properties. Among these strategies, both annual and trans-annual plant priming with different types of elicitors might provide efficient ways to better face (a)biotic stresses. The use of epigenetic exchanges between scion and rootstocks and/or the creation of non-targeted epigenetic variations at a genome-wide scale, or targeted using epigenetic editing, may provide innovative and promising avenues for grapevine improvement to face challenges imposed by climate changes.

Developing an in vitro elicitation strategy for specialized secondary metabolites production in adventitious root cultures of Primula veris subsp. veris

The demand for new sources of bioactive plant secondary metabolites (SMs) with importance as pharmaceutical and food additives, cosmetics and flavors, have emerged as rising scientific topic in parallel to the protection of natural habitats due to overexploitation and decreasing of biodiversity. Cowslip (Primula veris L. subsp. veris) is a perennial medicinal plant in which pharmaceutically important SMs such as phenolic acids glycosides (primulaverin, primeverin) and triterpene saponins (primulic acid I and II) are produced in the roots and aerial parts. These metabolites serve as quality markers for the evaluation of raw materials used for the production of expectorant and diuretic drugs. Alternatively to traditional soil-cultivation of whole plants, in vitro adventitious root production systems have the potential for elevated and stable production of plant SMs through elicitation processes. Additionally, these systems have an advantageous perspective from ecological and economical aspect comparing with conventional method for mass production of valuable compounds. In the present study eight abiotic elicitors [salicylic acid (SA), cazeine hydrolysate (CH), L-proline, silver nitrate (AgNO3), cobalt chloride (CoCl2), sucrose, jasmonic acid (JA) and putrescine], under a 60-day culture period into 250 mL flasks were tested. Afterwards, the following three elicitors applied in single (100 mg/L CH, 100 mg/L L-proline, 25 μM JA) or combinations (JA + CH, JA + L-proline), under two exposure times (30 and 60 days). The results showed that primeverin [35.7 mg/g dry weight (DW)], and cumulative phenolic acids glycosides (52.9 mg/g) content, yield index (YI) of primeverin (97.4 mg of pure dry extract), cumulative phenolic acids glycosides (144.4 mg), primulic acid I (37.2 mg), primulic acid II (9.1 mg) and cumulative saponins (45.4 mg), as well as root fresh biomass growth rate (× 10.2-fold), and root DW (2.7 g) were promoted after elicitation with 100 mg/L L-proline for 60 days. Primulaverin (23.6 mg/g), primeverin (14.4 mg/g) and the cumulative phenolic acids glycosides (38.1 mg/g) content was considerably maximized after treatment with 25 μM JA for 30 days. Combined elicitation of roots with 25 μM JA + 100 mg/L L-proline for 30 days, indicated the highest content in primulic acid II (5.9 mg/g), cumulative saponins (22 mg/g), while primulic acid I represented the highest content under 100 μM JA for 60 days (27 mg/g). Among the eight elicitors tested, L-proline, JA, and L-proline + JA proved to be the most beneficial treatments for SMs production. Following that, root fresh biomass growth rate (× 8.1), content, and YI of primulaverin (14.3 mg/g, 149.1 mg), primeverin (0.3 mg/g, 3.2 mg), cumulative phenolic acids glycosides (14.6 mg/g, 152.3 mg), primulic acid I (10.3 mg/g, 93.3 mg), primulic acid II (2.5 mg/g, 19.2 mg), and cumulative saponins (12.8 mg/g, 112.5 mg) were considerably higher after 90 days of culture in a 2 L balloon bubble type bioreactor system than after 60 days. Elicitor type, elicitor concentration, and elicitation exposure duration are factors that play a key role in the production of SMs. In the present study, the importance of abiotic elicitation strategies, and bioreactor systems which are novel in the scale-up process, on adventitious root in vitro cultures of P. veris subsp. veris have been discussed in detail and are highlighted for the first time. The production systems applied herein lay the possibilities for the large-scale manufacturing of specialized plant-derived SMs including triterpene saponins and phenolic acid glycosides, presenting commercial applications due to higher root biomass and bioactive compounds productivity obtained.

Methyl jasmonate and salicylic acid as powerful elicitors for enhancing the production of secondary metabolites in medicinal plants: an updated review.

Plant secondary metabolites are bioactive scaffolds that are crucial for plant survival in the environment and to maintain a defense mechanism from predators. These compounds are generally present in plants at a minimal level and interestingly, they are found to have a wide variety of therapeutic values for humans. Several medicinal plants are used for pharmaceutical purposes due to their affordability, fewer adverse effects, and vital role in traditional remedies. Owing to this reason, these plants are exploited at a high range worldwide and therefore many medicinal plants are on the threatened list. There is a need of the hour to tackle this major problem, one effective approach called elicitation can be used to enhance the level of existing and novel plant bioactive compounds using different types of elicitors namely biotic and abiotic. This process can be generally achieved by in vitro and in vivo experiments. The current comprehensive review provides an overview of biotic and abiotic elicitation strategies used in medicinal plants, as well as their effects on secondary metabolites enhancement. Further, this review mainly deals with the enhancement of biomass and biosynthesis of different bioactive compounds by methyl jasmonate (MeJA) and salicylic acid (SA) as elicitors of wide medicinal plants in in vitro by using different cultures. The present review was suggested as a significant groundwork for peers working with medicinal plants by applying elicitation strategies along with advanced biotechnological approaches.

Impact of elicitors on essential oil compositions and phytochemical constituents in Lavandula stoechas L.

Lavandula stoechas L. (LS) is an aromatic evergreen herb used broadly in the food, pharmaceutical, and perfume industries. However, the inducer effect of elicitors on secondary metabolites (SMs) biosynthesis in LS is nebulous. In addition, the precise mechanism of elicitors in cells remains unexplored. Hence, the primary objective of this study was to analyze the changes in phytochemical compositions of LSs treated with a biotic elicitor (chitin) and an abiotic one (copper nanoparticle) under in vitro and greenhouse conditions, with the aim of choosing an appropriate elicitor type, concentration, and exposure time for this species. In this study, the biochemical function of four chitin concentrations (i.e. 0, 50, 100 & 200 mg L−1) and four copper oxide nanoparticle concentrations (i.e. 0, 25, 50, & 100 mg L−1) at two exposure times (i.e. 5 & 10 days) was investigated in LS so as to compare with the un-elicited explants and the original plant materials. The analysis showed that the highest contents of the total phenolic (4.68 mg g−1 FW), flavonoids (0.68 mg g−1 FW), anthocyanins (36.51 mg g−1 FW), and flavonols (0.29 mg g−1 FW) compounds were observed in the elicited LSs. Besides, the role of elicitors in augmenting the percentage of SMs was intelligible, especially ‘lavandulol’, ‘1,8-cineole’, ‘germacrene D’, and ‘(E)-nerolidol’, which increased by 21.68%, 17.21%, 9.33%, and 8.11%, respectively. In conclusion, these findings indicate that utilizing elicitors at optimal concentrations and with timely durations of exposure can largely assist in improving the biotechnological production of SMs in LS, so that their potential for industrial use can be actualized.

Biotechnological intervention in genetic improvement and regulation of secondary metabolites production in Ocimum sanctum L

Ocimum sanctum L. is the most significant wellspring of medications utilized in the pharmaceutical industries and in the field of medicine. O. sanctum has a distinctive combination of pharmacological actions that support resilience and wellbeing. The secondary metabolites of O. sanctum show beneficial effects in the treatment of various diseases. This plant contains anti-oxidant properties and high amount of phenolic compounds which protect the body from toxin-induced damage. Due to its very high demand and less yield of the pharmaceutical content or secondary metabolites, there has been a persistent need to improve the productivity of the plant by using modern technology. There are various biotechnological methodologies which are utilized for the genetic improvement of this therapeutic plants viz micropropagation, direct or indirect in vitro regeneration, secondary metabolite enhancement by different types of elicitors, somatic embryogenesis and genetic transformation by various gene transfer approaches like Agrobacterium tumefiaciens, particle bombardment, etc. Genetic engineering for improvement of production of secondary metabolite and its biosynthesis pathways by overexpressing vital genes involved in the metabolite biosynthesis were reviewed. Omics techniques were also studied for understanding the genome structure, candidate genes and candidate proteins involved in secondary metabolites production. Overall, this review paper discusses the application of biotechnological techniques for enhancement of secondary metabolites production in O. sanctum.

Effect of explant type (leaf, stem) and 2,4-D concentration on callus induction: influence of elicitor type (biotic, abiotic), elicitor concentration and elicitation time on biomass growth rate and costunolide biosynthesis in gazania (Gazania rigens) cell suspension cultures

Gazania rigens (L.) Gaertn. (Asteraceae) is a medicinal plant with high ornamental potential and use in landscaping. The therapeutic potential of sesquiterpene lactones (SLs) as plant natural products for pharmaceutical development has gained extensive interest with costunolide (chemical name: 6E,10E,11aR-6,10-dimethyl-3-methylidene-3a,4,5,8,9,11a-hexahydrocyclodeca[b]furan-2-one) used as a popular herbal remedy due to its anti-cancer, antioxidant, anti-inflammatory, anti-microbial, anti-allergic, and anti-diabetic activities, among others. In the present study, two explant types (leaf, stem) and four 2,4-dichlorophenoxy acetic acid (2,4-D) concentrations (0, 0.5, 1 and 2 mg/L) were tested for callusing potential. The results showed that stem explants treated with 1.5 mg/L 2,4-D exhibited higher callus induction percentage (90%) followed by leaf explants (80%) with 1 mg/L 2,4-D, after a 4-week period. Cell suspension cultures were established from friable callus obtained from stem explants following a sigmoid pattern of growth curve with a maximum fresh weight at 20 days of subculture and a minimum one at 5 days of subculture. In the following stage, the effects of elicitation of cell suspension cultures with either yeast extract (YE) or methyl jasmonate (MeJA), each applied in five concentrations (0, 100, 150, 200 and 250 mg/L) on cell growth (fresh and dry biomass) and costunolide accumulation were tested. After 20 days of culture, YE or MeJA suppressed cell growth as compared to the non-elicited cells, while costunolide accumulation was better enhanced under the effect of 150 mg/L MeJA followed by 200 mg/L YE, respectively. In the subsequent experiment conducted, the optimal concentration of the two elicitors (200 mg/L YE, 150 mg/L MeJA) was selected to investigate further elicitation time (0, 5, 10, 15 and 20 days). The results revealed that YE biotic elicitation stimulated cell growth and costunolide production, being maximum on day 20 for fresh biomass, on day 5 for dry biomass and on day 15 for the bioactive compound. Accordingly, cell growth parameters were maximized under the effect of abiotic elicitation with MeJA for 15 days, while highest costunolide content was achieved after 10 days. Overall, MeJA served as a better elicitor type than YE for biomass and costunolide production. Irrespective of elicitor type, elicitor concentration and elicitation time, maximal response was obtained with 150 mg/L MeJA for 10 days regarding costunolide accumulation (18.47 ppm) and 15 days for cell growth (fresh weight: 954 mg and dry weight: 76.3 mg). The application of elicitors can lead the large quantity of costunolide to encounter extensive range demand through marketable production without endangering of G. rigens.Graphical

Elicitor-Induced VOC Emission by Grapevine Leaves: Characterisation in the Vineyard.

The present study is aimed at determining whether leaf volatile organic compounds (VOCs) are good markers of the grapevine response to defence elicitors in the field. It was carried out in two distinct French vineyards (Burgundy and Bordeaux) over 3 years. The commercial elicitor Bastid® (Syngenta, Saint-Sauveur, France) (COS-OGA) was first used to optimise the VOCs’ capture in the field; by bagging stems together with a stir bar sorptive extraction (SBSE) sensor. Three elicitors (Bastid®, copper sulphate and methyl jasmonate) were assessed at three phenological stages of the grapevines by monitoring stilbene phytoalexins and VOCs. Stilbene production was low and variable between treatments and phenological stages. VOCs—particularly terpenes—were induced by all elicitors. However, the response profiles depended on the type of elicitor, the phenological stage and the vineyard, and no sole common VOC was found. The levels of VOC emissions discriminated between weak (Bastid® and copper sulphate) and strong (methyl jasmonate) inducers. Ocimene isomers were constitutively present in the overall blends of the vineyards and increased by the elicitors’ treatments, whilst other VOCs were newly released throughout the growing seasons. Nonetheless, the plant development and climate factors undoubtedly influenced the release and profiles of the leaf VOCs.

Research progress on culture technologies,chemical components,and pharmacological activities of Saussurea involucrata cells

Saussurea involucrata,a traditional Chinese medicinal material,is effective in the treatment of rheumatoid arthritis with cold-dampness blockage syndrome,cold pain in lower abdomen,and menstrual irregularities. However,due to the specific habitat,low natural reproduction rate,slow growth,and overexploitation,it is at the high risk of extinction. S. involucrata cells can be obtained through callus culture,suspension culture,and hairy root culture. This study highlighted the influences of reactor type,culture system,precursor,elicitor type, and light wavelength on the suspension culture of S. involucrate cells. The chemical components of S. involucrata cells mainly include phenylpropanoids,flavonoids,lignans,and steroids,among which phenylpropanoids are the most abundant. S. involucrata cells have multiple pharmacological activities of anti-inflammation,analgesia,activating blood and resolving stasis,immunoregulation,increasing bone density,lowering blood lipids,anti-hypoxia,anti-exercise fatigue,anti-radiation,anti-obesity,and anti-oxidation. Moreover,it has the potential of treating aplastic anemia. This study reviews the cell culture technologies,chemical components,and pharmacological activities of S. involucrata cells,laying a basis for the further research,development,and utilization.

Three Types of Elicitors Induce Grapevine Resistance against Downy Mildew via Common and Specific Immune Responses.

Three recognized plant defense stimulators (PDS), methyl jasmonate (MeJA), benzothiadiazole (BTH) and phosphonates (PHOS), were sprayed on grapevine Vitis vinifera cuttings and conferred resistance to the biotrophic pathogen Plasmopara viticola. The effects on molecular defense-related genes and polyphenol content (stilbenes and flavanols) were revealed at 6 and 8 days post-elicitation. The transcript accumulation was consistent with the signaling pathway specific to the elicitor, salicylic acid for BTH, and jasmonic acid for MeJA, with some cross-talks. PHOS tended to modulate the defense responses like BTH. Moreover, in response to a downy mildew inoculation, the leaves pre-treated with PHOS and BTH overproduced pterostilbene, and after MeJA treatment, piceids and ε-viniferin, compared to uninoculated elicitor-treated leaves. These results provide evidence of the different modes of action of PDS and their role in sustainable viticulture.

Effect of methyl jasmonate and salicylic acid on the production of metabolites in cell suspensions cultures of Piper cumanense (Piperaceae)

Elicitation of cell suspensions culture is a strategy that could increase the production of secondary metabolites under controlled conditions. This research evaluated the effect of methyl jasmonate-MeJA and salicylic acid-SA as elicitors on the production of metabolites in cell suspensions of P. cumanense. The type of elicitor (MeJA or SA), the concentration of elicitor (10 μM and 100 μM), and time of exposition (3, 12, 24 h) on cell suspension were evaluated. Metabolic profiles of intracellular and extracellular extracts were analyzed by UHPLC-DAD and GC–MS. Differential production of metabolites was dependent on the type of elicitor, its concentration, and the time of exposition. Treatments with 100 μM SA were conducted to high production of 5-hydroxymethylfurfural (6.3 %), phenol (6.5 %), and (Z)-9-octadecenamide (8.8 %). This is the first report of elicitation on cell suspensions in the Piper genus and contributes to understanding the effect of MeJA and SA on metabolite production in plant cell culture.

Fungal Cell Wall and Methyl-\u03b2\u2013Cyclodextrin Synergistically Enhance Paclitaxel Biosynthesis and Secretion in Corylus avellana Cell Suspension Culture

Paclitaxel is the top-selling chemotherapeutic drug used for the treatment of lung, ovarian and breast cancer as well as Kaposi’s sarcoma. Cell suspension culture (CSC) of Corylus avellana has been addressed as a promising alternative for producing paclitaxel. In this study, endophytic fungus strain YEF33 was isolated from Taxus baccata and identified as Coniothyrium palmarum. The effects of the elicitors derived from this fungus including cell extract, culture filtrate and cell wall (CW) and also chitin, alone or in combination with Methyl-β-Cyclodextrin (MBCD), on paclitaxel biosynthesis in C. avellana CSC were assayed for the first time. CW of C. palmarum was the most efficient fungal elicitor for paclitaxel biosynthesis in C. avellana CSC. The results revealed that MBCD affected paclitaxel biosynthesis differently depending on fungal elicitor type and vice versa. MBCD, either alone or in combination with fungal elicitors, induced a high secretion of paclitaxel, suggesting the decrement of toxicity and retro-inhibition processes of paclitaxel for cells. The joint effects of C. palmarum CW (2.5% (v/v) on 17th day) and 50 mM MBCD synergistically enhanced paclitaxel biosynthesis (402.4 µg l−1; 5.8-fold), 78.6% of which (316.5 µg l−1) were secreted into culture medium, a level 146% higher than that in control.

Elicitation: A biotechnological tool for enhanced production of secondary metabolites in hairy root cultures.

Elicitation is a possible aid to overcome various difficulties associated with the large-scale production of most commercially important bioactive secondary metabolites from wild and cultivated plants, undifferentiated or differentiated cultures. Secondary metabolite accumulation in vitro or their efflux in culture medium has been elicited in the undifferentiated or differentiated tissue cultures of several plant species by the application of a low concentration of biotic and abiotic elicitors in the last three decades. Hairy root cultures are preferred for the application of elicitation due to their genetic and biosynthetic stability, high growth rate in growth regulator-free media, and production consistence in response to elicitor treatment. Elicitors act as signal, recognized by elicitor-specific receptors on the plant cell membrane and stimulate defense responses during elicitation resulting in increased synthesis and accumulation of secondary metabolites. Optimization of various parameters, such as elicitor type, concentration, duration of exposure, and treatment schedule is essential for the effectiveness of the elicitation strategies. Combined application of different elicitors, integration of precursor feeding, or replenishment of medium or in situ product recovery from the roots/liquid medium with the elicitor treatment have showed improved accumulation of secondary metabolites due to their synergistic effect. This is a comprehensive review about the progress in the elicitation approach to hairy root cultures from 2010 to 2019 and the information provided is valuable and will be of interest for scientists working in this area of plant biotechnology.

Species‐specific elicitors induce tea leaf to arrest the endoparasitoid Ascogaster reticulata (Hymenoptera: Braconidae)

AbstractAscogaster reticulata Watanabe (Hymenoptera: Braconidae) is an egg‐larval endoparasitoid of the smaller tea tortrix, Adoxophyes honmai Yasuda. Recent studies have examined tritrophic interactions among Camellia sinensis, A. honmai and A. reticulata, but the effect of non‐host insects on the induction of tea plant that may affect foraging behaviour of A. reticulata remains unclear. In this study, we selected two non‐host insects, Homona magnanima Diakonoff and Ostrinia furnacalis (Guenée), as representative species in our bioassays. Tea leaves were treated with homogenized female reproductive tissues of a non‐host insect in comparison with untreated leaves in a choice test. Residence times of parasitoids on both leaves were recorded. The parasitoids seemed to prefer walking on leaves treated with homogenates of H. magnanima over untreated leaves, but the difference in residence times was not significant. In contrast, its residence time on leaves treated with homogenates of O. furnacalis was significantly shorter than that on untreated leaves. Thus, the induction of tea leaf surface chemicals may differ among moth species, which may produce different types of elicitors. This difference may, in turn, affect the host‐searching behaviour of A. reticulata.

Efficient enhancement of gallic acid accumulation in cell suspension cultures of Barringtonia racemosa L. by elicitation

This study was conducted to evaluate the effects of elicitation process on gallic acid accumulation in the cell suspension cultures of Barringtonia racemosa L. Gallic acid was acknowledged as the main bioactive compound from phenolic group in this species. Two types of elicitors at various concentrations from biotic (10, 150 and 300 mg/l chitosan) and abiotic (1, 15 and 30 mg/l silver nitrate) origins were added into the cell suspension cultures of B. racemosa and were further harvested after 24, 48 and 72 h of elicitor feeding for gallic acid content analysis by using high performance liquid chromatography (HPLC). Elemental composition of the treated cultures which showed the greatest accumulation of gallic acid were further examined through elemental differential x-ray (EDX) analysis. The results revealed that the cultures treated with 30 mg/l silver nitrate and harvested after 24 h of culture recorded the greatest fresh weight of cell biomass (325.77 ± 2.46 g/l), meanwhile the greatest dry weight (DW) was identified in the cultures treated with 150 mg/l chitosan harvested after 72 h of culture (17.81 ± 0.82 g/l). After 72 h of elicitation, the cultures treated with 30 mg/l silver nitrate accumulated the highest gallic acid content up to 2.64 folds higher (193.83 ± 25.96 µg/g DW) than that of control. Besides, this analysis showed that the deficiency and depletion of certain mineral elements in the optimally elicited cell cultures could be attributed to the increased accumulation of gallic acid. The study suggested the effectiveness of elicitation process in enhancing the accumulation of gallic acid in the cell suspension cultures of B. racemosa.