This study aims to address the effects of different concentrations (0, 0.1, 1.0, 10, 100 or 1000 mg L−1) of engineered zinc oxide (ZnO) nanoparticles (34 nm in size) on growth parameters, steviol ...glycosides (rebaudioside A and stevioside) production and antioxidant activities in the tissue culture grown shoots of Stevia rebaudiana Bertoni. The highest percentage of shoot formation (89.6%) at 1 mg L−1 of ZnO nanoparticles concentration suggests a positive influence of ZnO nanoparticles on S. rebaudiana growth as compared to other treatments with or without ZnO nanoparticles. Additionally, HPLC results illustrate a significant enhancement of steviol glycosides (almost doubled as compared to the control) in micropropagated shoots grown under an oxidative stress of 1 mg L−1 of ZnO nanoparticles. This finding is further affirmed by an increased 2,2-diphenyl-1-picryl hydrazyl (DPPH) scavenging activity, total anti-oxidant capacity, total reducing power, total flavonoid content and total phenolic content, with an ascending oxidative pressure and generation of reactive oxygen species (ROS). However, the antioxidant activities, formation of secondary metabolites and the physiological parameters showed a sudden decline after crossing a threshold of 1 mg L−1 concentration of ZnO nanoparticles and falls to a minimum at 1000 mg L−1, elucidating maximum phytotoxic effect of ZnO nanoparticles at this concentration. This is the first study evaluating both the favorable and adverse effects of ZnO nanoparticles employed to a highly valuable medicinal plant, S. rebaudiana.
•Maximum rebaudioside-A and stevioside at 1 mg/L concentration of ZnO nanoparticles.•ZnO nanoparticles affects physiological parameters and steviol glycoside content.•ROS as a key factor for physiology and biochemical aspects of Stevia rebaudiana.
Copper oxide (CuO) nanoparticles (NPs) synthesized through co-precipitation method were employed in MS media during in vitro culture of
Stevia rebaudiana
. Physiological characteristics, production ...of steviol glycosides, and antioxidative parameters were investigated in regenerated plants. CuO NPs had crystalline monoclinic cubic cuprous oxides with average size 47 nm. The NPs were applied at 0, 0.1, 1.0, 10, 100 and 1000 mg/L in MS media for direct organogenesis of
S. rebaudiana
from nodal segments. Shoot organogenesis was found highest (88.5%) at 10 mg/L CuO and average shoot length, mean number of shoot per explant, and fresh weight were also found significantly higher at the same concentration. High performance liquid chromatography (HPLC) illustrated significant rise of bioactive major steviol glycosides (rebaudioside A and stevioside) at 10 mg/L CuO NPs in MS media. The oxidative stress produced by CuO nanoparticles on
S. rebaudiana
was affirmed by antioxidant activities i.e. total antioxidant activity (TAC), total reducing power (TRP) and 2,2-diphenyl-1-picryl hydrazyl (DPPH)-free radical scavenging activity. The oxidative stress generated by NPs involved production of antioxidative molecules total phenolic content (TPC), total flavonoid content (TFC) depending on NPs concentration. The study concludes that copper oxide nanoparticles functions as a stimulator of bioactive components productions, and can be employed in in vitro batch cultures.
The present paper describes a detailed study of a highly efficient protocol to multiply the number of haploids in sugar beet production and subsequent chromosome doubling. The protocol involves an ...experiment investigating factorial interactions between cold pretreatment, seven genotypes of sugar beet, and kinetin to improve haploid embryo induction. In addition, the effects of color of ovules and flower bud position on haploid embryo induction were investigated. After subjecting the data to analysis of variance or Student’s
t
test (
P
< .05), the effect sizes of the independent variables were also estimated. Cold pretreatment was effective in stimulating the ovules. The haploid embryo induction rate for 1-week cold pretreated ovules (9.01%) was higher than that of freshly cultured ones (6.15%). In comparison with hormone-free medium (5.16%), the gynogenesis rate for the media supplemented with 0.05 or 0.5 mg L
−l
kinetin increased to 7.58 and 10.05%, respectively. The genotype responses were significantly different. Interactions of kinetin × cold pretreatment, genotype × hormonal treatment, genotype × cold pretreatment, and the three-way interaction were statistically significant. Moreover, the main effects of flower bud position, ovule color, and comma-form ovule on gynogenic response were significant. After investigating the effect of 5 g L
−l
colchicine for 3, 5, or 7 min on one genotype’s (SG2) specimens, all the haploid plantlets from the other genotypes were treated for 5 min as the best treatment. The paper discusses interactions of the factors, which may be interesting for others aiming to breed doubled haploid sugar beet or possibly other related plant species.
For sugar beet (
Beta vulgaris
) breeding, producing homozygous lines through haploid and doubled haploid techniques are preferred over conventional and time-consuming methods. Doubled haploid sugar ...beet production necessitates inducing ovules to develop into haploid plants, referred to as gynogenesis. The protocol involves an interaction between cold pretreatment of six genotypes of sugar beet inflorescences at 4 °C for 1 week or more and 6-benzylaminopurine (BAP) concentrations (1 or 2 mg L
−1
) to increase the response rate of haploid embryo induction. Compared with freshly cultured ovules (6.49%), cold pretreatment for 1 week almost doubled the mean of haploid plantlet induction rate (11.3%), whereas pretreatment for more than 1 week was not as effective as the control. Addition of 2 mg L
−1
BAP to the culture medium nearly doubled the induction rate of the cultured ovules (10.75%), followed by 1 mg L
−1
BAP (7.78%) in comparison with hormone-free medium (5.69%). The highest gynogenesis rate (37.8%) was achieved when ovules were cultured on medium containing 2 mg L
−1
BAP following 1-week cold pretreatment. This combination approximately tripled the mean total haploid embryo induction rate of all the genotypes to 16.3% in comparison with the control (5.74%). However, the addition of BAP resulted in vitrification proportionately. As a result, 2 mg L
−1
BAP decreased the normal plantlet emergence (NPE) to one-third (7.59%) while 1 mg L
−1
BAP had a moderate effect (NPE: 18.98%) in comparison with hormone-free treatment (NPE: 24.35%). The results indicate that the combination of cold pretreatment and BAP is very effective in inducing haploid plants from recalcitrant genotypes of sugar beet, but BAP can have both advantages and disadvantages.
Nanoparticles are known to play remarkable role as abiotic stress elicitors in plants. This study reports the comparative analysis of effects produced by capped zinc oxide (ZnO)-polyethylene glycol ...(PEG), ZnO-polyvinyl pyrrolidone (PVP), copper oxide (CuO)-PEG, CuO-PVP and uncapped (ZnO and CuO) nanoparticles on the medicinal plant, Stevia rebaudiana raised in vitro for the production of commercially important sweetener compounds. In context of shoot organogenesis, ZnO-PEG, ZnO-PVP, CuO-PEG, CuO-PVP were employed to the growth medium that resulted in increased growth parameters, and larger content of steviol glycosides as compared to the shoots raised in medium containing ZnO and CuO, revealed by high-performance liquid chromatography. In the meanwhile, non-enzymatic antioxidant activities including total phenolic content, total flavonoid content, total antioxidant capacity, total reducing power and 2,2-diphenyl-1-picryl hydrazyl-free radical scavenging activity were calculated and showed comparatively greater amounts in shoots grown in medium containing capped ZnO or CuO nanoparticles. Furthermore, the ZnO and its derivatives revealed to be more reactive at 1 mg/l of concentration. Whereas, the CuO and its derivatives produced greater response on Stevia at 10 mg/l concentration of nanoparticles. This study paves the way for more such studies encompassing capped and uncapped nanoparticles and their ultimate effect on in-vitro grown plant tissues for the production of active metabolites on industrial scale.
The short-chain dehydrogenase/reductase (SDR) gene family is widely distributed in all kingdoms of life. The
genes, 3β-hydroxysteroid dehydrogenase (
) and progesterone 5-β-reductases (
,
) play a ...crucial role in cardenolide biosynthesis pathway in the
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
,
and
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
,
and
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
genes leading to enhanced salt tolerance, which opens a window for developing saline-tolerant plants via plastid genetic engineering.
•This study provides: Very simple, practical, and cost effective propagation for Stevia rebaudiana.•A knowledge of some crop management technics to enhance leaf quantity and quality: for the best ...time of harvest.•A clear understanding of the influence of traditional and innovative methods of vegetative propagation: in terms of high quality leaf production having high Reb-A/Stevioside ratio and comparing seedlings (seed-derived) and regenerants (node-derived) plants in field.•This report is directly applicable to the industrial production of Stevia plants.•Synseed protocol was developed for Stevia in case of scarcity of stock plant, and seed material.
Stevia rebaudiana Bertoni is a self-incompatible and the pollination is an entomophilous short-day plant. Rebaudioside A, as an individual steviol glycoside, is of particular interest in global sweetener market due to its most desirable flavour profile as compared to stevioside having aftertaste bitterness. In the present investigation, regenerant formation was performed for 6 weeks, in which randomly selected nodes excised from in vitro germinated seedlings were cultured on solid Murashige and Skoog medium (MS) with or without growth regulators (6-benzylaminopurine- BAP or kinetin- KIN) at various concentrations (ranging from 0.1 to 2.0mg/L). Irrespective of the medium composition, the results showed that all treatments were effective for shoot induction, producing an average of 2 shoots per explant after three weeks of culture. Following subsequent sub-culturing on MS medium at 3-week intervals, all the shoots regenerated from the nodes were transferred to MS medium with or without indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) or naphthalene acetic acid (NAA) at two different concentrations (0.25 or 0.50mg/L) for root formation for 3 weeks. IAA was more effective for root formation, producing 7.6 roots per shoot with 100% rooting frequency. All the regenerants (∼13.5cm in length) were potted and successfully acclimatized in a greenhouse for 2 weeks, and then transferred to the field for 14 weeks with a high survival rate (>99%). Similarly, seedlings (8 weeks-old) derived from seed germination in pots were also transferred to the same field in a different plot. There was no significant difference in terms of morphological, yield performance and steviol glycoside compositions between regenerants and seedlings sampled from two developmental periods (late vegetative and flowering period). It was clearly shown that clonal propagation using nodal explants was effective for superior stock plant production with high Reb-A content (11.7% w/w).
Display omitted
•Synthesis and characterization of alpha and beta substituted phthalocyanines.•Study of photophysical and photochemical properties of these compounds.•The effects of the substituent ...positions and metal differences in phthalocyanine.•Investigation of spectroscopic properties of the novel phthalocyanines.
The synthesis of novel peripheral or non-peripheral tetra-mesityloxy substituted metal-free, zinc and indium phthalocyanines, which are highly soluble in organic solvents, has been achieved. The phthalocyanines have been characterized by UV–vis, IR, MALDI-TOF Mass, 1H NMR, 13C NMR spectroscopies and elemental analysis. On their spectroscopic, photochemical and photophysical properties, the effects of the substituent position and the variety of central metal ions in phthalocyanine cavity are also investigated. Photodegradation, singlet oxygen and fluorescence quantum yields, and fluorescence lifetimes in dimethylformamide for the phthalocyanines are described. These properties of the compounds are very useful for photodynamic therapy applications and their high singlet oxygen quantum yields are very important for Type II mechanisms. The phthalocyanines can be appropriate candidates as Type II photosensitizers.
PDF
