In vitro tuberization in Dioscorea alata L. ‘Brazo fuerte’ and ‘Florido’ and D. abyssinica Hoch

Nodal cuttings of D. alata L. Barzo fuerte and Florido, as well as of D. abyssinica Hoch, were cultured in vitro in order to assess the influence of the photoperiod on the production of microtubers. For both species, the highest number of microtubers was obtained under 16 and 24-h photoperiods, whereas larger microtubers were generally produced at 8-h photoperiod. In D. alata, further increase in microtuber size was observed in a culture medium where NH₄NO₃ was omitted. This effect was less noticeable in D. abyssinica.     

In vitro propagation and cytology of wild yams,Dioscorea abyssinica Hoch. and D. mangenotiana Miège

Two wild yams of West Africa, Dioscorea abyssinica Hoch, and D. mangenotiana Miège were micropropagated from nodal cultures. Both species produced 4–5 nodes per each node cultured. The size of nodal cuttings was critical, segments shorter than 0.5 cm being less suitable for micropropagation. The number of nodes produced was constant even after 5 cycles of subculture; however, D. abyssinica continuous subculture decreased propagation efficiency, resulting in a reduced number of reculturable nodes at each cycle. In D. mangenotiana, the decrease in multiplication efficiency affected both the number of total and reculturable nodes. Large-sized microtubers were induced on nodal segments maintained under 8-h daylength in both species. In D. abyssinica, however, microtubers were induced on media containing 20, 40, 60 and 80 g l^-1 sucrose, whereas in D. mangenotiana only 40 and 60 g l^-1 sucrose favoured tuberization. Cytological studies confirmed that the chromosome number of D. abyssinica was 2n=40, although a high incidence of cytochimerism and cells with 2n=38 were observed in root meristems. In D. mangenotiana clones, the chromosome number was 2n=40, as against 2n=72 and 2n=80 reported in literature. This species also displayed karyological stability.Abbreviations BA benzyladenine - NAA naphthaleneacetic acid - PPF photosynthetic photon flux     

Effects of 4-CPPU on in vitro multiplication and sustainable generation of Hibiscus rosa-sinensis L. ‘White Butterfly’

There are more than nine thousand cultivars of Hibiscus rosa-sinensis L., with a series of flowers with shapes, colors and new cultivars continues as generated through both traditional and modern breeding techniques. In this study, advanced biotech methods of in vitro culture have been used to identify a technique for the efficient mass multiplication of H. rosa-sinensis ‘White Butterfly’, using phenyl urea, N-(2-Chloro-4-pyridyl)-N′-phenylurea (4-CPPU). For the first time, the effects of 4-CPPU for stimulating axillary shoot proliferation and multiple shoot regenerations from nodal explants were evaluated, and the optimal nutrient media deduced. From the diverse concentrations as 0.1, 0.5, 2.5, 5.0 & 10.0 µM of 4-CPPU, the highest frequency of shoots was recorded at 2.5 µM supplied in Murashige and Skoog (MS, pH-5.8) medium. After eight-weeks of culture, on an average of 6.7 shoot were obtained on this media with shoot heights of 4.2 cm from each explant. With the involvement of 0.5 µM-IBA (indole-3-butyric acid) in MS medium the regenerated shoots were rooted and followed by successful acclimation to ex vitro conditions. The ploidy consistency among the micro-plants was analyzed using flow cytometry and compared with ex vitro grown plants. No differences in the ploidy levels were observed among the 4-CPPU induced plants, when compared with the donor plants.     

Micropropagation of Hibiscus moscheutos L. ‘Luna White’: effect of growth regulators and explants on nuclear DNA content and ploidy stability of regenerants

In Vitro Cellular & Developmental Biology - Plant - Hibiscus moscheutos L., also known as hardy hibiscus, is valued for its medicinal and ornamental attributes. It is usually propagated via...     

Influence of meristem-tip size and location on morphological development in Dioscorea cayenensis-D. rotundata complex ‘Grosse Caille’ and one genotype of D. praehensilis

In vitro morphological development of meristem-tips, excised from microshoots, is reported for one clone Grosse Caille of D. cayenensis-D. rotundata complex and for one clone of D. praehensilis. The effects of size and location of meristem-tip on viability and morphological development after 3, 8 and 11 months in vitro culture were studied. The larger size of meristem-tip gave the best rooting and plantlet formation while the smaller size gave the best bud production. Axillary buds were more reactive than apical meristem-tips in callusing and rooting when small-sized meristems of the Grosse Caille clone were used; the use of larger meristem-tips did not induce more differences between apical and axillary buds. The production of plantlets was successful, after 11 months of culture, with a score of 82 and 39 % survivors, for Grosse Caille clone and D. praehensilis genotype, respectively.Abbreviations Ap apical meristem-tips - ApLS large-sized apical meristem-tips - Ax axillary meristem-tips - AxLS large-sized axillary meristem-tips - BA 6-benzyladenine - cv cultivar - LS large-sized meristem-tip - NAA naphthalenacetic acid - SS small-sized meristem-tip     

Genetic and biochemical studies on perchloroethylene ‘in vitro’ and ‘in vivo’

Perchloroethylene (PCE) was tested in a diploid strain (D7) of the yeast Saccharomyces cerevisiae in suspension tests with and without a mammalian microsomal activation system (S9) and ‘in vivo’ by the intrasanguineous host-mediated assay. In addition, enzyme alteration studies were performed in mice non-pretreated or pretreated with phenobarbital + β-naphthoflavone. PCE did not induce any genetic effect either ‘in vitro’ or ‘in vivo’. In the suspension test, PCE was more toxic without metabolic activation and less toxic with mammalian microsomal activation. The enzymatic determinations showed an increase of the aminopyrine demethylase activity and of the level of cytochrome P-450.     

Effects of nutrient addition on growth and rhizosphere pH of Leucadendron ‘Safari Sunset’

A greenhouse experiment was conducted to establish the optimal fertilization management for Leucadendron Safari Sunset (Leucadendron salignum × L. laureolum). Addition of NPK and micronutrient fertilizer or raising phosphorus concentration by itself increased total fresh weight and improved plant growth. Elevating the total nutrients or P concentration increased N and P concentrations. Clusters of proteoid roots were present along the root system of plants irrigated with tap-water, whereas few proteoid roots developed on plants irrigated with complete nutrient solution when only P was omitted, and none developed in any of the other treatments with P present.The pH in leachate of plants irrigated with tap water or with high nutrient levels (100, 20 and 100 mg L^-1 of N, P and K, respectively) was consistently lower compared with leachate without plants. Increasing concentration resulted in a significant change in the pH values (pH in leachate with plant – pH in leachate without plant) from negative to positive. This phenomenon is probably related to rhizosphere effects due to plant and microbial activity.     

The effects of IAA and tetcyclacis on tuberization in potato (Solanum tuberosum L.) shoot cultures in vitro

Potato (Solanum tuberosum cv. Désirée) shoots grown in vitro in continuous darkness or in long days (LDs), were used to investigate indole-3-acetic acid (IAA) effects on stolon initiation and tuber formation, combining IAA with increased or decreased gibberellin levels. An increased gibberellin (GA) level was achieved by the applying 1 μM GA₃, while decreased gibberellin level was presumably realized by the adding 3 μM tetcyclacis (Tc). About 15% of potato shoots developed stolons both in LDs and in darkness. Stolon initiation was stimulated by GA₃ in darkness and by Tc in LDs. Tuber formation was strongly inhibited in LDs and by GA₃ both in light and darkness, but stimulated in darkness at low GA level. Exceptionally, tuber formation occurred in LDs at the highest Tc concentrations, in about 25% of explants. Indole-3-acetic acid alone stimulated stolon formation in LDs, both in the presence or absence of GA₃. IAA alone also stimulated tuber formation in dark-grown shoots, but could not overcome the inhibitory effect of LDs. Indications that, depending on their concentration ratio, IAA may interact with GA₃ in different tuberization phases, have been discussed. Radomir Konjević—Deceased in July 2006.     

In vitro culture of vanhoutte's spirea explants from ‘secondary cultures’ and dormant stems forced in solutions containing plant growth regulators

Explants from new growth of forced dormant stems and secondary cultures of Vanhoutte's spirea were cultured on Linsmaier and Skoog (L.S.) medium containing benzyladenine (BA), indoleacetic acid (IAA), thidiazuron (TDZ), and zeatin. The dormant stems were forced by immersing their basal portions in forcing solutions containing 626 µM 8-hydroxyquinoline citrate (8-HQC) and 2% sucrose. BA and gibberellic acid (GA₃) were also added into the forcing solutions to determine if explants obtained from the new growth will benefit from this treatment when culturedin vitro.L.S. medium supplemented with 5 µM BA alone, 5 µM BA plus 1 or 5 µM IAA, and 0.5 or 0.75 µM TDZ alone produced the best shoot proliferation for both sources of explants. BA and GA₃ appeared to be taken up from the forcing solution by the new softwood growth. BA in the forcing solution stimulatedin vitro shoot proliferation in different degrees depending on the period of treatment, while GA₃ caused lessin vitro shoot proliferation. It is proposed that forcing solutions containing plant growth regulators (P.G.R.) are a useful approach for manipulating responses of plant tissues culturedin vitro.     

Effects of transforming growth factor-β1 and activin-A on in vitro porcine granulosa cell steroidogenesis

The mammalian ovarian cycle is a strictly regulated process that is dependent on the intimate interactions among the 3 cell types in the follicle — theca, granulosa, and oocyte. The cycle has been shown to be controlled by gonadotropins as well as locally produced peptide factors. In this study, an in vitro culture system was used to study the roles of 2 locally produced ovarian peptide factors, transforming growth factor-β₁ (TGF-β₁) and activin-A, on porcine granulosa cell steroidogenesis. Gonadotropin stimulated cultured porcine granulosa cells (from medium-sized follicles) were pretreated with 100 ng/ml follicle-stimulating hormone (FSH) for 48 h and then treated with 1 ng/ml TGF-β₁, 100 ng/ml activin-A, TGF-β₁ plus activin-A, or received no treatment (control) for 48 h, From our previous studies, the concentrations of the 2 growth factors were determined to produce maximal antisteroidogenic effects in porcine granulosa cells. Progesterone (P₄) production, estradiol-17β (E₂) production, and aromatase activity for gonadotropin-stimulated porcine granulosa cells treated with TGF-β₁, activin-A, and TGF-β₁ plus activin-A were significantly (P < 0.05) reduced fromthat of the control. The same procedures were conducted on basal steroidogenesis studies in which no pretreatment with FSH was performed. Both P₄ and E₂ production and aromatase activity for porcine granulosa cells treated with TGF-β₁, activin-A and TGF-β₁ plus activin-A were significantly (P < 0.05) inhibited compared with the control. Our results indicate that both TGF-β₁ and activin-A can inhibit FSH-stimulated and basal steroidogeneses in porcine granulosa cells and, thus, may act as local atretic factors during follicular development. When the 2 growth factors were given in combination at concentrations that would produce maximal steroidogenic inhibition, they were not able to produce a synergistic effect. These results are consistent with the current theory that TGF-β₁ and activin-A may act via the same messenger system, a serine-threonine kinase.     

Effect of potassium humate on apple cv. ‘Golden Delicious’ cultured in vitro

The effects of humic substances on in vitro culture of Golden Delicious apple are reported. Potassium humate (KH) when used in proliferation showed a negative interaction with BA while it enhanced rooting when IBA was not present in the culture medium. In the presence of IBA, KH increased root number and reduced root growth. The highest concentration tested, 500 mg l^-1, caused a drastic reduction in root system development. 50 mg l^-1 KH hastened rooting and plants grew more rapidly when transferred to soil.     

Effects of serial subculture in vitro on the endogenous levels of indole-3-acetic acid and abscisic acid and rootability in microcuttings of ‘Jonathan’ apple

Proliferating axillary shoots of the difficult-to-root apple cultivar Jonathan acquired an enhanced ability to form adventitious roots with increasing number of subcultures in vitro. The transition between the difficult-to-root and the easy-to-root condition occurred at the fourth subculture.Endogenous levels of free IAA and ABA in shoot tissues were analysed by gas chromatography/mass spectrometry/single ion monitoring (GC/MS/SIM) using negative ion chemical ionisation. Tissues from the mother plants grown in the glasshouse contained more IAA and ABA than those from tissue-culture material. After establishment in vitro there was no variation in the IAA content throughout the subcultures but a decrease in ABA content was observed after the fourth transfer. The IAA/ABA ratio increased from 0.2 in difficult-to-root shoots from the initial culture up to 0.7 in easy-to-root shoots from the long-term subculture.     

Effects of plant growth promoting bacteria and mycorrhizal on Capsicum annuum L. var. aviculare ([Dierbach] D’Arcy and Eshbaugh) germination under stressing abiotic conditions

Capsicum annuum var. aviculare to Tarahumara and Papago Indians and farmers of Sonora desert is a promising biological and commercial value as a natural resource from arid and semiarid coastal zones. Traditionally, apply synthetic fertilizers to compensate for soil nitrogen deficiency. However, indiscriminate use of these fertilizers might increase salinity. The inoculation by plant growth promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF) represents an alternative as potential bio fertilizer resources for salty areas. Seeds ecotypes from four areas of Sonora desert (Mazocahui, Baviacora, Arizpe, La Tortuga), in order to inoculate them with one species of PGPB and AMF. Two germination tests were carried out to study the effect of salinity, temperature regime (night/day) and inoculation with PGPB and AMF growth factors measured on germination (percentage and rate), plant height, root length, and produced biomass (fresh and dry matter). The results indicated that from four studied ecotypes, Mazocahui was the most outstanding of all, showing the highest germination under saline and non-saline conditions. However, the PGPB and AMF influenced the others variables evaluated. This study is the first step to obtain an ideal ecotype of C. a. var. aviculare, which grows in the northwest of México and promoting this type of microorganisms as an efficient and reliable biological product. Studies of the association of PGPB and AMF with the C. a. var. aviculare-Mazocahui ecotype are recommended to determine the extent to which these observations can be reproduced under field conditions.     

Effects of Schisandrin B and α-tocopherol on lipid peroxidation, in vitro and in vivo

Effects of Schisandrin B (Sch B) and -tocopherol (-TOC) on ferric chloride (Fe³⁺) induced oxidation of erythrocyte membrane lipids in vitro and carbon tetrachloride (CCl₄) induced lipid peroxidation in vivo were examined. While -TOC could produce prooxidant and antioxidant effect on Fe³⁺-induced lipid peroxidation, Sch B only inhibited the peroxidation reaction. Pretreatment with -TOC (3 mmol/kg/day × 3) did not protect against CCl₄-induced lipid peroxidation and hepatocellular damage in mice, whereas Sch B pretreatment (0.3 mmol/3.0 mmol/kg/day × 3) produced a dose-dependent protective effect on the CCl₄-induced hepatotoxicity. The ensemble of results suggests that the ability of Sch B to inhibit lipid peroxidation, while in the absence of pro-oxidant activity, may at least in part contribute to its hepatoprotective action.Abbreviations ALT alanine aminotransferase - CCl₄ carbon tetrachloride - Fe³⁺ ferric chloride - MDA malondialdehyde - Sch B Schisandrin B - TBA 2-thiobarbituric acid - TBARS thiobarbituric acid reactive substances - -TOC dl--tocopherol     

‘In vitro’ and ‘in situ’ decomposition of nuisance macroalgae Cladophora glomerata and Pilayella littoralis

The decomposition of two macroalgal species Cladophora glomerata (CHLOROPHYTA) and Pilayella littoralis (PHAEOPHYTA) was studied in the laboratory and field conditions. These species are known to cause the extensive macroalgal blooms in the whole coastal range of the Baltic Sea. The objective of the experiments was to determine decomposition rates of the macroalgae, follow the changes in tissue nutrient content and validate the role of benthic invertebrates in this process. In the laboratory conditions, the differences in the decomposition rates of the algae were mainly due to the oxygen conditions. The weight loss of C. glomerata was slightly higher in anaerobic conditions than in aerobic conditions. If 99% of initial dry weight of P. littoralis was lost in aerobic conditions then only 20% was lost in anaerobic conditions. In general, the loss of phosphorus and nitrogen in algal tissues followed the weight loss. As an exception, the amount of nitrogen changed very little during the decomposition of C. glomerata. In field conditions, the photosynthetic activity exceeded the decomposition rate of C. glomerata at lower temperatures in spring. The decomposition of P. littoralis was estimated at 49% of its initial dry weight. The addition of benthic invertebrates had no effect on the decomposition process. In summer, the decomposition rates were estimated at 65% for C. glomerata and 68% for P. littoralis being in the same order of magnitude as observed in laboratory conditions. If the decomposition of C. glomerata was faster at the end of the experiment, the most significant losses of weight of P. littoralis took place during the first 2 weeks of deployment. Idotea baltica significantly contributed to the loss of C. glomerata. The decomposition rate of P. littoralis was reduced by the presence of Mytilus edulis and increased by Gammarus oceanicus.     

Effects of Exogenous Application of Melatonin on Quality and Sugar Metabolism in ‘Zaosu’ Pear Fruit

Melatonin (MT) modulates a wide range of physiological functions with pleiotropic effects in plants. In this study, we studied the effect of exogenous applications of MT to pear trees on indicators of pear fruit quality. The results showed that MT increased the size of pear fruit by improving the net photosynthetic rate and maximal quantum efficiency of photosystem II photochemistry during the late stage of pear fruit development. Overall, MT increased fruit weight by 47.85% compared to the control. During the period of fruit maturation, MT increased the content of soluble sugars, particularly sucrose and sorbitol, likely as a result of improved starch accumulation. Expression levels of the invertase gene Pbinvertase 1/2 were lower in MT-treated fruit that resulted in lower enzyme activity, whereas activity of sucrose phosphate synthase was greater due to enhanced levels of expression of PbSPS1/2/3. Thus, application of melatonin improved sucrose content. This study shows that the application of MT to pear trees may be utilized for the production of larger and sweeter fruit of higher economic value.