In silico designing and characterization of outer membrane protein K (OmpK) from Vibrio anguillarum and its expression in Nicotiana tabacum for the development of a plant-based vaccine against fish vibriosis

Vibriosis is caused by Vibrio anguillarum in various species of aquaculture. A novel, secure, and stable vaccine is needed to eradicate vibriosis. Here, for reverse vaccinology and plant-based expression, the outer membrane protein K (OmpK) of V. anguillarum was chosen due to its conserved nature in all Vibrio species. OmpK, an ideal vaccine candidate against vibriosis, demonstrated immunogenic, non-allergic, and non-toxic behavior by using various bioinformatics tools. Docking showed the interaction of the OmpK model with TLR-5. In comparison to costly platforms, plants can be used as alternative and economic bio-factories to produce vaccine antigens. We expressed OmpK antigen in Nicotiana tabacum using Agrobacterium-mediated transformation. The expression vector was constructed using Gateway® cloning. Transgene integration was verified by polymerase chain reaction (PCR), and the copy number via qRT-PCR, which showed two copies of transgenes. Western blotting detected monomeric form of OmpK protein. The total soluble protein (TSP) fraction of OmpK was equivalent to 0.38% as detected by ELISA. Mice and fish were immunized with plant-derived OmpK antigen, which showed a significantly high level of anti-OmpK antibodies. The present study is the first report of OmpK antigen expression in higher plants for the potential use as vaccine in aquaculture against vibriosis, which could provide protection against multiple Vibrio species due to the conserved nature OmpK antigen.

Isolation of the 3β-HSD promoter from Digitalis ferruginea subsp. ferruginea and its functional characterization in Arabidopsis thaliana

BACKGROUND

Although members of the SDR gene family (short chain dehydrogenase) are distributed in kingdom of life, they have diverse roles in stress tolerance mechanism or secondary metabolite biosynthesis. Nevertheless, their precise roles in gene expression or regulation under stress are yet to be understood.

METHODS

As a case study, we isolated, sequenced and functionally characterized the 3β-HSD promoter from Digitalis ferruginea subsp. ferruginea in Arabidopsis thaliana.

RESULTS

The promoter fragment contained light and stress response elements such as Box-4, G-Box, TCT-motif, LAMP element, ABRE, ARE, WUN-motif, MYB, MYC, W box, STRE and Box S. The functional analysis of the 3β-HSD promoter in transgenic Arabidopsis seedlings showed that the promoter was expressed in cotyledon and root elongation zone in 2 days' seedlings. However, this expression was extended to hypocotyl and complete root in 6 days' seedlings. In 20 days-old seedlings, promoter expression was distributed to the whole seedling including hydathodes aperture, vascular bundle, shoot apical meristem, trichomes, midrib, leaf primordia, hypocotyl and xylem tissues. Further, expression of the promoter was enhanced or remained stable under the different abiotic stress conditions like osmotic, heat, cold, cadmium or low pH. In addition, the promoter also showed response to methyl jasmonate (MeJA) application. The expression could not be induced in wounded cotyledon most likely due to lack of interacting elements in the promoter fragment.

CONCLUSIONS

Taken together, the 3β-HSD promoter could be a candidate for the development of transgenic plants especially under changing environmental conditions.

AB0495 SERUM AND URINE GALECTIN-9, IP-10 AND SIGLEC-1 AS BIOMARKERS OF DISEASE ACTIVITY IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS

Background

Galectin-9, interferon-inducible protein-10 (IP-10) and sialoadhesin (SIGLEC-1) are proteins associated with interferon signature, and considered as potential biomarkers reflecting disease activity in patients with systemic lupus erythematosus (SLE).

Objectives

In this study, we aimed to investigate the association of serum and urine levels of galectin-9, IP-10 and SIGLEC-1 with disease activity in patients with SLE.

Methods

Sixty-three patients with active SLE (31 renal and 32 extrarenal) were included in the study. Thirty inactive patients with SLE (15 renal and 15 extrarenal) and 32 healthy volunteers were selected as control groups. Serum (s) and urine (u) levels of galectin-9, IP-10 and SIGLEC-1 were tested using ELISA. Urine levels of biomarkers were normalized by urine creatinine.

Results

Groups were comparable with regard to sex and age distribution. Of 125 participants, 102 (81.6%) were female and median age was 33 (28-44.5) years. Proliferative lupus nephritis (LN) (class III/III+V and IV/IV+V) were found in 22 patients with active renal SLE (70.9%), while 6 patients (19.3%) had pure class V and 3 (9.7%) had class II LN. Levels of sIP-10, uIP-10, sGalectin-9 and uSIGLEC-1 were significantly higher in the active SLE group compared to the inactive SLE group (sIP-10 p=0.046, uIP-10 p<0.001, sGalectin-9 p=0.031 and uSIGLEC-1 p=0.006); however, no differences were detected in the comparison of uGalectin-9 and sSIGLEC-1 between the groups (uGalectin-9 p=0.180 and sSIGLEC-1 p=0.699) (Table 1). Serum and urine levels of galectin-9, IP-10 and SIGLEC-1 did not differ between patients with active renal and extrarenal SLE. Levels of sIP-10, uIP-10 and uSIGLEC-1 were correlated with SLE Disease Activity Index (SLEDAI). Serum and urine levels of all biomarkers were re-tested in 41 of 63 patients (65%) with active SLE after a median treatment of 8 (5-22.5) months. At the time of the second tests, there was a significant decrease in disease activity as measured by SLEDAI [2 (0-4)] compared to the time of the first tests [10 (6-15.5)]. Comparison of sGalectin-9 levels between the serum at the time of active disease and remission showed a very significant decline (p<0.001) as shown in Figure 1. uGalectin-9, sIP-10 and uSIGLEC-1 also decreased after treatment; however, the difference was not statistically significant.

Table 1.

Serum and urine levels of biomarkers across study groups.

BiomarkerActive SLE(n=63)Inactive SLE(n=30)Healthy Control(n=32)sGalectin-9 (ng/ml)11.73 (7.52-14.15)8.66 (7.51-10.02)5.61 (4.56-6.6)sIP-10 (pg/ml)279.4 (147.5-430.3)173.4 (142.2-247.9)74.3 (58.8-103)sSIGLEC-1 (pg/ml)181.2 (157.8-213.9)182.5 (169.9-203.1)258.3 (179-602)uGalectin-9 (ng/ml)8.83 (4.07-18.11)11.54 (7.03-15.07)10.63 (5.55-17.4)uIP-10 (pg/ml)34.4 (15.9-73,9)20.8 (9.9-53.3)12.2 (1.8-25.7)uSIGLEC-1 (pg/ml)321 (236.3-370.9)297.6 (247.7-371)290 (205.1-323.5)uGalectin-9 (ng/mgCre)15.50 (9.60-32.05)11.41 (8.78-19.54)13.57 (11.27-22.08)uIP-10 (pg/mgCre)73.4 (40.9-136.9)26.1 (18.1-55.1)16.4 (5-32.5)uSIGLEC-1 (pg/mgCre)619.6 (389.4-1056.5)393.2 (248.6-715.8)425.6 (264.7-925.9)Figure 1.

Serum levels of galectin-9 before and after the treatment in 41 patients with active SLE.

Conclusion

sIP-10, uIP-10, sGalectin-9 and uSIGLEC-1 are associated with disease activity in SLE. None is able to discriminate active renal from active extrarenal disease. sGalectin-9 may be a valuable biomarker to monitor response after treatment for active disease (Funded by Scientific Research Projects Coordination Unit of Istanbul University. Project number: TSA-2019-34218).

Disclosure of Interests

None declared

Plastidial Expression of 3β-Hydroxysteroid Dehydrogenase and Progesterone 5β-Reductase Genes Confer Enhanced Salt Tolerance in Tobacco

The short-chain dehydrogenase/reductase (SDR) gene family is widely distributed in all kingdoms of life. The SDR genes, 3β-hydroxysteroid dehydrogenase (3β-HSD) and progesterone 5-β-reductases (P5βR1, P5βR2) play a crucial role in cardenolide biosynthesis pathway in the Digitalis species. However, their role in plant stress, especially in salinity stress management, remains unexplored. In the present study, transplastomic tobacco plants were developed by inserting the 3β-HSD, P5βR1 and P5βR2 genes. The integration of transgenes in plastomes, copy number and transgene expression at transcript and protein level in transplastomic plants were confirmed by PCR, end-to-end PCR, qRT-PCR and Western blot analysis, respectively. Subcellular localization analysis showed that 3β-HSD and P5βR1 are cytoplasmic, and P5βR2 is tonoplast-localized. Transplastomic lines showed enhanced growth in terms of biomass and chlorophyll content compared to wild type (WT) under 300 mM salt stress. Under salt stress, transplastomic lines remained greener without negative impact on shoot or root growth compared to the WT. The salt-tolerant transplastomic lines exhibited enhanced levels of a series of metabolites (sucrose, glutamate, glutamine and proline) under control and NaCl stress. Furthermore, a lower Na+/K+ ratio in transplastomic lines was also observed. The salt tolerance, mediated by plastidial expression of the 3β-HSD, P5βR1 and P5βR2 genes, could be due to the involvement in the upregulation of nitrogen assimilation, osmolytes as well as lower Na+/K+ ratio. Taken together, the plastid-based expression of the SDR genes leading to enhanced salt tolerance, which opens a window for developing saline-tolerant plants via plastid genetic engineering.

POS0766 CLUSTER ANALYSIS AND COMPARISON OF CUMULATIVE DAMAGE BY DIAPS IN A SINGLE CENTER COHORT OF APS PATIENTS

Background:

Antiphospholipid syndrome (APS) is a chronic autoimmune disease with significant morbidity and mortality. The recently developed damage index for APS (DIAPS) considers thrombotic APS specific damage.

Objectives:

Herein we aimed to identify disease clusters based on clinical characteristics and compare DIAPS between these clusters in a single center cohort of patients with APS ± systemic lupus erythematosus (SLE).

Methods:

This retrospective study included 237 consecutive patients with APS [114 primary APS (PAPS) and 123 SLE+APS]. Data regarding demographics, clinical and laboratory characteristics and cardiovascular risk factors were retrieved from the existing database and revised. Two-step cluster analysis was performed. Cumulative damage was calculated for all patients by applying DIAPS as described previously.

Results:

237 patients were classified into 4 subgroups by cluster analysis. Cluster 1 (n=74) consisted of older patients with arterial-predominant VT, livedo reticularis and increased cardiovascular risk, cluster 2 (n=70) of SLE+APS patients with thrombocytopenia and heart valve disease, cluster 3 (n=59) of patients with venous-predominant VT, less extra-criteria manifestations and cluster 4 (n=34) of patients with only PM with a lower frequency of extra-criteria features and cardiovascular risk (table 1).

Table 1.

Demographic, clinical and laboratory characteristics of clusters

All (n=237)Cluster 1 (n=74)Cluster 2 (n=70)Cluster 3(n=59)Cluster 4 (n=34)PAge (years), median (range)43 (20-81)51 (20-81)40 (27-72)42 (24-69)40.5 (26-65)<0.001Duration of disease (years), median (range)9.5 (1-37.7)13.1 (1-37.7)10.4 (1-28.7)8.5 (1-32.8)7 (1-22.4)0.028Female, n (%)198 (83.5)56 (75.7)61 (87.1)47 (79.7)34 (100)<0.05SLE, n (%)123 (51.9)31 (41.9)46 (65.7)32 (54.2)14 (41.2)<0.05Vascular thrombosis, n (%)191 (80.6)73 (98.6)59 (84.3)59 (100)0 (0)<0.001Arterial thrombosis, n (%)109 (46)50 (67.6)31 (44.3)28 (47.5)0 (0)<0.001Venous thrombosis, n (%)112 (47.3)36 (48.6)37 (52.9)39 (66.1)0 (0)<0.001Pregnancy morbidity, n (%)117 (49.4)22 (29.7)46 (65.7)15 (25.4)34 (100)<0.001Livedo reticularis, n (%)38 (16)21 (28.4)10 (14.3)5 (8.5)2 (5.9)<0.01Thrombocytopenia, n (%)81 (34.2)4 (5.4)65 (92.9)4 (6.8)8 (23.5)<0.001Heart valve disease, n (%)92 (38.8)32 (43.2)46 (65.7)8 (13.6)6 (17.6)<0.001Arterial hypertension, n (%)101 (42.6)49 (66.2)34 (48.6)18 (30.5)0 (0)<0.001Hyperlipidemia, n (%)103 (43.5)69 (93.2)26 (37.1)0 (0)8 (23.5)<0.001Smoking, n (%)58 (24.5)31 (41.9)7 (10)17 (28.8)3 (8.8)<0.001Lupus anticoagulant, n (%)156 (65.8)53 (71.6)48 (68.6)35 (59.3)20 (58.8)0.36Anticardiolipin IgG/IgM, n (%)155 (65.4)46 (62.2)46 (65.7)38 (64.4)25 (73.5)0.71Anti-β2-glycoprotein I IgG/IgM, n (%)93 (39.2)25 (33.8)33 (47.1)26 (44.1)9 (26.5)0.13Triple aPL positivity, n (%)45 (19)12 (16.2)16 (22.9)13 (22)4 (11.8)0.46

Cluster 2 had the highest cumulative damage (mean DIAPS 2.48 ± 1.67) followed by cluster 1 (2.24 ± 1.44), cluster 3 (1.69 ± 1.27) and cluster 4 (0.32 ± 0.68). Comparison of DIAPS (total and major domains) between the clusters is shown in figure 1.

Patients with SLE+APS had a higher mean DIAPS compared to those with PAPS (2.10 ± 1.61 vs 1.69 ± 1.47, P=0.046). Cardiovascular domain was the most frequently affected DIAPS domain in both groups. Proteinuria and avascular necrosis were significantly more frequent in SLE+APS (9.8% vs 2.2%, P=0.02 and 5.7% vs 0%, P=0.009, respectively). DIAPS was positively correlated with disease duration (r=0.192, P=0.003).

Conclusion:

Elder APS patients with arterial thrombosis and increased cardiovascular risk and SLE+APS patients with extra-criteria manifestations had higher cumulative DIAPS. Longer disease duration, higher frequency of major organ involvement and higher immunosuppressive usage may have contributed to this difference. Therefore, control of cardiovascular risk factors, prevention and effective treatment of SLE flares may help to reduce damage in these subgroups.

Figure 1.

Comparison of mean DIAPS (total and major domains) between the clusters

Disclosure of Interests:

None declared

Production of Doubled Haploid Sugar Beet (Beta vulgaris L.) Plants Through Gynogenesis

Haploid and doubled haploid plant production through unpollinated ovule culture, with diverse benefits and applications, is considered among the most effective and advantageous breeding method for sugar beet (Beta vulgaris L.). It is known that sugar beet is not responsive to androgenesis, which is widely used for most plant species. Sugar beet is a recalcitrant plant in vitro due to the very low spontaneous chromosome doubling and low gynogenesis rate. Thus, a steadily increasing gynogenesis efficiency has always been an important target for an efficient sugar beet breeding program. Given the scarcity of published papers focusing on gynogenesis in sugar beet, this chapter describes haploid and doubled haploid production through ovule culture of unfertilized flowers as a practical method.

Applications of carbon nanomaterials in the plant system: A perspective view on the pros and cons

With the remarkable development in the field of nanotechnology, carbon-based nanomaterials (CNMs) have been widely used for numerous applications in different areas of the plant system. The current understanding about the CNMs' accumulation, translocation, plant growth responses, and stress modulations in the plant system is far from complete. There have been relentless efforts by the researchers worldwide in order to acquire newer insights into the plant-CNMs interactions and the consequences. The present review intends to update the reader with the status of the impacts of the different CNMs on plant growth. Research reports from the plant biotechnologists have documented mixed effects (which are dependent on CNMs' concentration) of the CNMs' exposure on plants ranging from enhanced crop yield to acute cytotoxicity. The growth and yield pattern vary from species to species and are dependent on the dosage of the CNMs applied. Studies found an increase in vegetative growth and yield of fruit/seed at lower concentration of CNMs, but a decrease in these observables were also noted when higher concentrations of CNMs were used. In general, at lower concentrations, CNMs were found to be effective in enhancing (water uptake, water transport, seed germination, nitrogenase, photosystem and antioxidant activities), activating (water channels proteins) and promoting (nutrition absorption); all these change when concentrations are raised. All these aspects have been reviewed thoroughly in this article, with a focus on the recent updates on the role of the CNMs in augmenting or retarding plant growth. Sections have been devoted to the various features of the CNMs and their roles in inducing plant growth, phytotoxic responses of the plants and overall crop improvement. Concluding remarks have been added to propose future directions of research on the CNMs-plant interactions and also to sound a warning on the use of CNMs in agriculture.

An Overview of Cardenolides in Digitalis - More Than a Cardiotonic Compound

The genus Digitalis L. containing species, commonly known as the "foxglove", is the main source of cardenolides, which have various pharmacological properties effective against certain pathological conditions including myocardial infarction, arterial hypertension, cardiac dysfunction, angina, and hypertrophy. Togehter with a prime effect of controlling the heart rhythm, many workers demonstrated that lanatoside C and some other cardiac glycosides are effective in several cancer treatments such as prostate and breast cancers. Due to digoxigenin derivatives of cardenolides, which are mainly used for medicinal purposes, such as digoxigenin, D. lanata as a main source is of great interest for commercial scale production of cardenolides in Europe. Phytochemical studies on cardenolides, naturally occurring plant secondary metabolites, have mainly focused on the species of the genus Digitalis L., as the members of this family have a high level and diverse content of cardenolides. During the last few decades, plant tissue culture techniques have been optimised for many plant species including Digitalis, however, the production capacity of cardenolides somehow failed to reach a commercially desired extent. In this review paper, the genus Digitalis is evaluated in terms of its main botanical and physiological features, traditional uses, molecular genetics and metabolomics, cellular mechanism of action, medicinal uses, clinical pharmacology, drug interactions, therapy in the management of cardiovascular disorders, potential utility of therapy in extracardiac conditions, and toxicity.

Influence of auxin and its polar transport inhibitor on the development of somatic embryos in Digitalis trojana

The present study reports the role of auxin and its transport inhibitor during the establishment of an efficient and optimized protocol for the somatic embryogenesis in Digitalis trojana Ivan. Hypocotyl segments (5 mm long) were placed vertically in the Murashige and Skoog medium supplemented with three sets [indole-3-acetic acid (IAA) alone or 2,3,5-triiodobenzoic acid (TIBA) alone or IAA-TIBA combination] of formulations of plant growth regulators, to assess their differential influence on induction and proliferation of somatic embryos (SEs). IAA alone was found to be the most effective, at a concentration of 0.5 mg/l, inducing ~ 10 SEs per explant with 52% induction frequency. On the other hand, the combination of 0.5 mg/l of IAA and 1 mg/l of TIBA produced significantly fewer (~ 3.6 SEs) and abnormal (enlarged, oblong, jar and cup-shaped) SEs per explant with 24% induction frequency in comparison to that in the IAA alone. The explants treated with IAA-TIBA exhibited a delayed response along with the formation of abnormal SEs. Our study revealed that IAA induces high-frequency SE formation when used singly, but the frequency gradually declines when IAA was coupled with increasing levels of TIBA. Eventually, our findings bring new insights into the roles of auxin and its polar transport in somatic embryogenesis of D. trojana.

CRISPR/Cas9-Mediated Immunity in Plants Against Pathogens

Global crop production is highly threatened due to pathogen invasion. The huge quantity of pesticides application, although harmful to the environment and human health, is carried out to prevent the crop losses worldwide, every year. Therefore, understanding the molecular mechanisms of pathogenicity and plant resistance against pathogen is important. The resistance against pathogens is regulated by three important phytohormones viz. salicylic acid (SA), jasmonic acid (JA) and ethylene (ET). Here we review possible role of CRISPR technology to understand the plant pathogenicity by mutating genes responsible for pathogen invasion or up-regulating the phytohormones genes or resistant genes. Thus hormone biosynthesis genes, receptor and feeding genes of pathogens could be important targets for modifications using CRISPR/Cas9 following multiplexing tool box strategy in order to edit multiple genes simultaneously to produce super plants. Here we put forward our idea thatthe genes would be either mutated in case of plant receptor protein targets of pathogens or up-regulation of resistant genes or hormone biosynthesis genes will be better choice for resistance against pathogens.

Effects of salicylic acid on thermotolerance and cardenolide accumulation under high temperature stress in Digitalis trojana Ivanina

Long periods of high temperature or transitory increased temperature, a widespread agricultural problem, may lead to a drastic reduction in economic yield, affecting plant growth and development in many areas of the world. Heat stress causes many anatomical and physiological changes in plants. Its unfavorable effects can be alleviated by thermotolerance induced by exogenous application of plant growth regulators and osmoprotectants or by gradual application of temperature stress. Digitalis trojana Ivanina is an important medicinal plant species well known mainly for its cardenolides. The production of cardenolides via traditional agriculture is commercially inadequate. In this study, elicitation strategies were employed for improving crop thermotolerance and accumulation of cardenolides. For these purposes, the effects of salicylic acid (SA) and/or high temperature treatments in inducing cardenolide accumulation and thermotolerance were tested in callus cultures of D. trojana. Considerable increases in the production of cardenolides (up to 472.28 μg.g(-1) dry weight, dw) and induction of thermotolerance capacity were observed when callus cultures were exposed to high temperature for 2 h after pretreating with SA. High temperature treatments (2 h and 4 h) caused a marked reduction in superoxide dismutase (SOD; EC 1.15.1.1) and catalase (CAT; EC 1.11.1.6) activities, while SA pretreatment increased their activities. High temperature and/or SA appeared to increase the levels of proline, total phenolic, and flavonoid content. Elevated phenolic accumulation could be associated with increased stress protection. These results indicated that SA treatments induced synthesis of antioxidants and cardenolides, which may play a significant role in resistance to high temperature stress.

Influence of nutrient media on callus induction, somatic embryogenesis and plant regeneration in selected Turkish crocus species

Callus induction, somatic embryogenesis and plant regeneration were initiated in selected five species of Turkish crocus using three diffrent explants (leaf, stem and corm) cultured on four different media (MS, GB5, LS and CHE). The highest frequencies of callus induction (100%) and shoot regeneration (70%, with 7.2 shoots/callus) were found in the crocus species Crocus oliveri ssp. Oliveri, using the MS medium containing 5% (w/v) sucrose supplemented with (4 mg/L NAA + 4 mg/L TDZ) and (2 mg/L IAA + 2 mg/L TDZ + 2 mg/L BAP). When the embryogenic calli were transferred into the four nutrient media containing (2 mg/L IAA + 2 mg/L TDZ) and 100 mg/L ABA, these further developed into cotyledonary embryos. Maximum number of somatic embryos (2.9 embryos per leaf explant, with a frequency 46.6%) was obtained in C. oliveri ssp. Oliveri. During subculture using the half strength media, cotyledonary embryos gradually developed into plantlets.

Somatic embryogenesis, pigment accumulation, and synthetic seed production in Digitalis davisiana Heywood

Digitalis davisiana, commonly called Alanya foxglove, from Turkey, is an important medicinal herb as the main source of cardiac glycosides, cardenolides, anthraquinones, etc. It is also known in the Indian Medicine for treatment of wounds and burns. It has ornamental value as well. Overexploitation of D. davisiana has led this species to be declared protected, and thereby encouraged various methods for its propagation. In this study, an optimized and efficient plant tissue culture protocol was established using cotyledonary leaf, hypocotyl and root explants of D. davisiana. Callus tissues were obtained from the cotyledonary leaf, hypocotyl and root segments cultured on Murashige and Skoog's (MS) medium containing different plant growth regulators. The maximum number of somatic embryos were achieved by the MS medium containing 6-benzyladenine (1.0 mg/L BAP) or 2,4-dichlorophenoxy acetic acids (0.1 mg/L 2,4-D), which produced an average of 8.3 ± 1.5 or 5.3 ± 1.5 embryos per cotyledonary leaf, respectively. After 3 wk of culture in MS medium supplemented with 1.0 mg/L 2,4-D, callus showed a clear accumulation of orange pigmentation. Shoot regeneration was remarkably higher (14.3 indirect shoots) in a combination of α-naphthalene acetic acid (0.25 mg/L NAA) plus 3.0 mg/L BAP than 2.0 mg/L zeatin (10.3 ± 0.5 direct shoots) alone. The shoots were successfully rooted on MS medium supplemented with NAA (0.1-1.0 mg/L). In addition, synthetic seeds were produced by encapsulating shoot tips in 4% sodium alginate solution. Maximum conversion frequency of 76.6% was noted from encapsulated shoot tips cultured on 0.25 mg/L NAA with 1.0 mg/L BAP. The encapsulated shoot tips could be stored up to 60 days at 4 °C. Regenerated plantlets of D. davisiana were successfully acclimatized and transferred to soil. This study has demonstrated successful preservation of elite genotypes of D. davisiana.

Hydrogen peroxide-induced antioxidant activities and cardiotonic glycoside accumulation in callus cultures of endemic Digitalis species

The effect of hydrogen peroxide (H2O2) on callus cultures of four Digitalis species (Digitalis lamarckii, Digitalis trojana, Digitalis davisiana and Digitalis cariensis) increased catalase (CAT), superoxide dismutase (SOD), total phenolic, proline activity and cardiotonic glycoside production. Callus derived from hypocotyl explants was cultured on Murashige and Skoog medium supplemented with 0.25 mg L(-1) indole-3-acetic acid (IAA) and 0.5 mg L(-1) thidiazuron (TDZ). After a month of culture, callus was transferred to MS medium containing 10 mM H2O2 and then incubated for 6 h. The amount of five cardenolides (Lanatoside C, Digitoxin, Digoxigenin, Gitoxigenin and Digoxin) as well as CAT, SOD, total phenolic, proline activity from Digitalis species were compared. No digoxin was detected in all treatments and control groups. The total cardenolides estimated were in the order of D. lamarckii (586.65  μg g(-1) dw), D. davisiana (506.79 μg g(-1) dw), D. cariensis (376.60 μg g(-1) dw) and D. trojana (282.39 μg g(-1) dw). It was clear that H2O2 pre-treatment resulted in an increase in enzymatic and nonenzymatic antioxidants. However, a significant negative relationship between cardenolides production and overall activities of CAT, SOD, total phenolic and proline was evident. The described protocol here will be useful for the development of new strategies for a large-scale production of cardenolides.

Calcium and magnesium elimination enhances accumulation of cardenolides in callus cultures of endemic Digitalis species of Turkey

Elimination of calcium (Ca), magnesium (Mg) or both from the medium of callus cultures of Digitalis davisiana Heywood, Digitalis lamarckii Ivanina, Digitalis trojana Ivanina and Digitalis cariensis Boiss. ex Jaub. et Spach increased cardenolides production. Callus was induced from hypocotyl segments from one-month old seedlings were cultured on MS medium containing 0.5 μg ml(-1) thidiazuron (TDZ) and 0.25 μg ml(-1) indole acetic acid (IAA). After 30 days of culture, callus was transferred in hormone-free MS medium (MSO) as well as Ca or Mg or both were completely eliminated from same medium. The amount of five cardenolides from D. davisiana Heywood, D. lamarckii Ivanina, D. trojana Ivanina and D. cariensis Boiss. ex Jaub. et Spach were compared. Higher amounts of five cardenolides and total cardenolides were obtained when callus of four Digitalis species were incubated on MS medium lacking both Ca and Mg. The mean contents of total cardenolides obtained were in the order of D. lamarckii (2017.97 μg g(-1))>D. trojana (1385.75 μg g(-1))>D. cariensis (1038.65 μg g(-1))>D. davisiana (899.86 μg g(-1)) when both Ca and Mg were eliminated from the medium, respectively. This protocol is useful for development of new strategies for the large-scale production of cardenolides.

Agrobacterium-mediated transformation of Sorghum bicolor using immature embryos

Successful efforts describing in vitro culturing, regeneration, and transformation of grain sorghum were reported, using particle bombardment, as early as 1993, and with Agrobacterium tumefaciens in 2000. Reported transformation efficiencies via Agrobacterium routinely range from 1 to 2%. Recently, such efficiencies via Agrobacterium in several plant species were improved with the use of heat and centrifugation treatments of explants prior to infection. Here, we describe the successful use of heat pretreatment of immature embryos (IEs) prior to Agrobacterium inoculation to increase routine transformation frequencies of a single genotype, P898012, to greater than 7%. This reproducible frequency was calculated as numbers of independently transformed IEs, confirmed by PCR, western, and DNA hybridization analysis, that produced fertile transgenic plants, divided by total numbers of infected IEs.

Efficient, reproducible Agrobacterium-mediated transformation of sorghum using heat treatment of immature embryos

A number of parameters related to Agrobacterium-mediated infection were tested to optimize transformation frequencies of sorghum (Sorghum bicolor L.). A plasmid with a selectable marker, phosphomannose isomerase, and an sgfp reporter gene was used. First, storing immature spikes at 4 degrees C before use decreased frequency of GFP-expressing calli, for example, in sorghum variety P898012 from 22.5% at 0 day to 6.4% at 5 days. Next, heating immature embryos (IEs) at various temperatures for 3 min prior to Agrobacterium infection increased frequencies of GFP-expressing calli, of mannose-selected calli and of transformed calli. The optimal 43 degrees C heat treatment increased transformation frequencies from 2.6% with no heat to 7.6%. Using different heating times at 43 degrees C prior to infection showed 3 min was optimal. Centrifuging IEs with no heat or heating at various temperatures decreased frequencies of all tissue responses; however, both heat and centrifugation increased de-differentiation of tissue. If IEs were cooled at 25 degrees C versus on ice after heating and prior to infection, numbers with GFP-expressing cells increased from 34.2 to 49.1%. The most optimal treatment, 43 degrees C for 3 min, cooling at 25 degrees C and no centrifugation, yielded 49.1% GFP-expressing calli and 8.3% stable transformation frequency. Transformation frequencies greater than 7% were routinely observed using similar treatments over 5 months of testing. This reproducible frequency, calculated as numbers of independent IEs producing regenerable transgenic tissues, confirmed by PCR, western and DNA hybridization analysis, divided by total numbers of IEs infected, is several-fold higher than published frequencies.

Site-directed mutagenesis of five conserved residues of subunit i of the cytochrome cbb3 oxidase in Rhodobacter capsulatus

Cytochrome cbb(3) oxidase is a member of the heme-copper oxidase superfamily that catalyses the reduction of molecular oxygen to the water and conserves the liberated energy in the form of a proton gradient. Comparison of the amino acid sequences of subunit I from different classes of heme-copper oxidases showed that transmembrane helix VIII and the loop between transmembrane helices IX and X contain five highly conserved polar residues; Ser333, Ser340, Thr350, Asn390 and Thr394. To determine the relationship between these conserved amino acids and the activity and assembly of the cbb(3) oxidase in Rhodobacter capsulatus, each of these five conserved amino acids was substituted for alanine by site-directed mutagenesis. The effects of these mutations on catalytic activity were determined using a NADI plate assay and by measurements of the rate of oxygen consumption. The consequence of these mutations for the structural integrity of the cbb(3) oxidase was determined by SDS-PAGE analysis of chromatophore membranes followed by TMBZ staining. The results indicate that the Asn390Ala mutation led to a complete loss of enzyme activity and that the Ser333Ala mutation decreased the activity significantly. The remaining mutants cause a partial loss of catalytic activity. All of the mutant enzymes, except Asn390Ala, were apparently correctly assembled and stable in the membrane of the R. capsulatus.

Common mullein (Verbascum thapsus L.): recent advances in research

Common mullein (Verbascum thapsus L.) is a medicinal plant readily found in roadsides, meadows and pasture lands and has been used to treat pulmonary problems, inflammatory diseases, asthma, spasmodic coughs, diarrhoea and migraine headaches. Although it has been used medicinally since ancient times, the popularity of common mullein has been increasing commercially for the past few years. Today, the dried leaves and flowers, swallow capsules, alcohol extracts and the flower oil of this plant can easily be found in health stores in the United States. The use of common mullein extracts in folk medicine begun recently to be supported by an increasing number of research studies. This paper thoroughly reviews all the scientific research related to Verbascum thapsus L. including plant tissue cultures and the biological properties of this plant.