In Vitro Morphophysiological Responses of Alternanthera Tenella Colla (Amaranthaceae) to Stress Induced by Cadmium and the Attenuating Action of Silicon

Despite having the ability to bioaccumulate trace elements such as cadmium (Cd), many species also present morphophysiological disorders that can hamper their use as phytoremediation plants. Since it can lead to alterations in biomass accumulation. The employment of elements that mitigate stress, such as silicon (Si), can diminish the deleterious effects caused by trace elements. The objective of this study was to analyze the anatomical and physiological modulations induced by the synergy between Cd and Si in Alternanthera tenella plants, as well as to elucidate whether Si can mitigate the harmful effects caused by Cd under in vitro conditions. Nodal segments were cultured in media containing a concentration gradient of Cd (0, 50, 100, or 200 μM) combined with two levels of Si (0 or 40 μM) for a total of eight treatments. After 34 days, the plants' anatomy, physiology, and tolerance index were analyzed. The plants presented anatomical adjustments (such as lower stomatal index and number of vessel elements), suggesting lower translocation of Cd to the aerial part. When cultured with 200 μM Cd, the plants presented the lowest Chl a/b ratio. In the presence of Si, the decline of this ratio was smaller. Plants exposed to Cd concentrations of 50 μM without Si presented a significant decrease in the performance of the photosynthetic apparatus and tolerance index. The presence of Si in the medium reduced the damages caused by cadmium to the plants' physiology, resulting in greater growth and higher tolerance to this element.

BA and TDZ in the Morphogenesis in Vitro of Passiflora Setacea

Passiflora setacea DC (Passifloraceae) is considered an important species in the genetic breeding of passion fruit. However, its use is limited due to low seed germination. This paper aimed to study the effect of cytokinins 6-benzyladenine (BA) and thidiazuron (TDZ) on the in vitro morphogenesis of P. setacea using three explants: hypocotyl, nodal segment, and root segment. The explants were induced to morphogenesis in MS medium modified and with different concentrations of BA and TDZ. After 55 days, the percentage of calluses and shoots were evaluated, and anatomical characterization was performed. The three explants used in the in vitro morphogenesis of P. setacea showed callus and shoots formation, but in greater numbers in the nodal segments treated with BA. TDZ isolated affected equal to or less than BA on callus and shoots formation for the three explants. Direct and indirect organogenesis was observed in the three types of explants. From the results obtained for plant regeneration via in vitro morphogenesis of P. setacea, it is recommended to use a nodal segment in MSM medium and supplemented with 2.22 μmol L-1 of BA.

Growth regulators and their reflection on different hop genotypes cultivated under in vitro conditions

Hops is a new culture in Brazil. Tissue culture can be an important technique for rapid hop propagation. This paper aims to characterize responses from different genotypes under different growth regulators through the interrelationship of response variables important to hop in vitro growth. Three genotypes were cultivated in six culture media with different combinations of growth regulators, BAP (6-benzylaminopurine), IAA (3-indolacetic acid) and GA3 (gibberellic acid). The means were compared by orthogonal contrasts and the interrelationship of the response variables was performed by path analysis. American genotypes showed favorable root development under the BAP + IAA combination, while the use of IAA improved shoot development. The origin of genotypes was important for defining the best protocol for in vitro cultivation. The path coefficient showed that the variable number of shoots has stronger direct effect on the number of nodal segments. Additionally, in tissue culture assays, the use of a covariable and proper error distribution significantly increased experimental accuracy.

In vitro propagation from nodal segments of Lippia origanoides (chemotype A)

ABSTRACT: This research described an efficient micropropagation protocol for Lippia origanoides (Verbenaceae). Sterile seeds were used to obtain germinated seedlings in Murashige and Skoog medium (MS) supplemented with sucrose and agar. The nodal segments obtained from seedlings were grown on MS medium supplemented with different concentrations of gibberellic acid (GA), benzylaminopurine (BAP) and 1-naphthalenacetic acid (NAA) with BAP. The callus induction, shoots length, shoots number and root length, were analyzed. The treatments showed high percentage of callus formation at 0.5 to 1.5 mg L-1 of BAP alone or in combination with NAA (0.1 mg L-1). The highest value of shoot number per nodal segments was obtained at 1.5 mg L-1 of BAP (4.3 ± 0.8). The obtained plantlets were better rooted in vitro in the absence of plant growth regulators (PGRs) and they showed acclimatization rate of 90%. We reported a protocol for in vitro propagation and acclimatization of L. origanoides for A chemotypes from Colombia.

A fast and effective protocol for obtaining genetically diverse stevia (Stevia rebaudiana Bertoni) regenerants through indirect organogenesis

Plant regeneration through indirect organogenesis allows obtaining genetic variability that can be used in the creation of new cultivars. The study presents a fast and effective protocol of one-step preparation of stevia (Stevia rebaudiana Bertoni) regenerants. To obtain callus tissue and shoot regeneration, leaves and nodal segments were used as primary explants, which were placed on MS (Murashige and Skoog) medium supplemented with plant growth regulators (PGRs): NAA (1-naphthaleneacetic acid – 2.0 mg·dm–3, BA (6-benzylaminopurine – 4.0 mg·dm–3), 2,4‑D (2,4-dichlorophenoxyacetic – 2.0 mg·dm–3). Callus tissue was formed on both types of explants, however, only those derived from nodal segments were proliferating. An average of 3.92 shoots per explant were obtained from leaf explants on the applied medium after 6 weeks of culture. The analysis of the morphogenetic capacity of the obtained regenerants was carried out on MS medium supplemented with PGRs – kinetin (0.25 mg·dm–3), BA (0.5 mg·dm–3). The evaluation of the mean number of shoots, mean shoot length (cm), and the mean number of nodes per shoot indicated phenotypic variability of regenerants. The use of RAPD (randomly amplified polymorphic DNA) markers confirmed the differences also at the DNA level. The proposed one-step indirect organogenesis regeneration protocol induced somaclonal variation of Stevia rebaudiana Bertoni and the obtained regenerants, after selection, could be used in the breeding of this species.

The Response of Vegetable Sweet Potato (Ipomoea batatas Lam) Nodes to Different Concentrations of Encapsulation Agent and MS Salts

As an emerging technology, shoot encapsulation has been employed in germplasm conservation, distribution, and micropropagation of elite plant species. However, the production of synthetic seeds of sweet potato via non-zygotic embryogenesis requires a large number of embryos per cultured callus suspension and is labour-intensive. Here, we reported a simple method of encapsulating in vitro derived vegetable sweet potato nodal segments with sodium alginate, calcium chloride (CaCl2), and Murashige and Skoog (MS) salts. The nodes encapsulated with 4% sodium alginate (w/v) and 100 mM CaCl2 were the most suitable for propagation. They had uniform spherical beads and took the least number of days to shoot and root emergence. These plantlets produced more leaves, roots, and long shoots. Further evaluation of the MS salts concentration revealed that the plantlets encapsulated and grown with ½ MS salts had the least days to shoot and root emergence. They also had a longer shoot, the highest conversion rate (99%), and the least leaf abscission (17%). Thus, the sweet potato nodal segments encapsulated with 4% sodium alginate, 100 mM CaCl2, and ½ MS salts could be used as excellent material for micropropagation, germplasm conservation, and exchange of sweet potato planting materials.

The Accumulation of Essential Oils In Organ Culture of Acinos Graveolens Via Methyl Jasmonate And Salicylic Acid Exertion

The impact of Salicylic acid (SA) and Methyl jasmonate (MJ) on growth, and essential oil quantity and quality in organ culture of Acinos graveolens were investigated. In the present study, nodal segments were used as explants for shoot production using MS media with BA and NAA. Afterward, they were transferred to liquid MS media culture containing SA and MJ with 50, 100, and 150 µM and their combinations (SA25+MJ25, SA50+MJ25, SA25+MJ50, and SA50+MJ50). After three weeks, samples were collected to assess the morphological and some growth parameters, quantitative changes in pigment amounts as well as volatile contents. Accordingly, almost all treatments led to a notable decrease in growth parameters in comparison with control. The highest amount of Chl a, b and carotenoids were achieved by MJ100, SA50, and SA25+MJ50, respectively. In addition, GC-MS results indicated 38 components of volatile products mainly alkane hydrocarbons and sesquiterpenes. The major identified compounds were Decane, Eicosane, and Germacrene D. Altogether, results asserted that SA25+MJ25 and SA100 were more efficient in the enhancement of essential oil content among all treatments.

Regeneration potential of different explants during micropropagation of neem tree (Azadirachta indica A. Juss.)

Azadirachta indica A. Juss., (Neem), a prodigious multipurpose tree, has immense potential to benefit mankind and to protect the environment. In order to investigate the effects of three different explants for its regeneration potential, de embryonated cotyledon, immature zygotic embryo and nodal segments from a 30 year old neem plus tree were used. Half strength MS medium with benzyl amino purine (3 mg/L) and naphthalene acetic acid (0.5 mg/L) and casein hydrolysate (1 g/L) was effective in shoot bud sprouting from both nodes and cotyledons. Half strength MS medium fortified with TDZ (0.2 mg/L) was effective for induction of somatic embryogenesis from zygotic embryos. Shoot buds initiated from the cotyledons produced a maximum number of shoots per explants (4.33) which on further sub culturing induced maximum multiple shoots (15) on half strength MS medium fortified with BAP (1.5 mg/L), NAA (0.5 mg/L) and CH (400 g /L) and the nodal explants induced only 4-5 axillary shoots on further sub culturing. Even though immature zygotic embryos produced more number of somatic embryos per explant (24.97) within a short time (30-45 days), the plantlet conversion was poor (25.52 %). In vitro rooting was observed in half strength MS medium supplemented with IBA (2 mg/L). The regeneration potential of de embryonated cotyledons through a simple regeneration system may be beneficial for efficient mass propagation of selected plus trees of neem.

An Effective Protocol for Carnation (Dianthus caryophyllus L.) cv. 'Geolei' Explants Sterilization for Successful Callusing and Shoot Regeneration

Carnation is a popular floricultural crop grown widely for its attractive cut flowers. Micro-propagation can be used to create large-scale carnation output. For growth and development, plants require some necessary nutrients as well as growth regulators. Due to the importance of carnation, the present work is carried out using leaf and nodal segments to examine the potential of several plant growth regulators for in vitro callus formation and adventitious shoot regeneration. Explants were sterilized properly with bavistin, sodium hypochlorite and mercuric chloride. The minor contaminated cultures were created by consecutively treating the explants with 0.25% bavistin, 0.50% sodium hypochlorite, and 0.1% mercuric chloride for ten, fifteen, and two minutes. MS media with 2.5 mg/l 2,4-dichlorophenoxy acetic acid (2,4-D) in combination with 0.75 mg/l naphthalene acetic acid (NAA) resulted in the maximum callus induction (90.47%) from leaf explants. Maximum shoots (76.47%) were produced in MS media supplemented with 2.0 mg/l Thidiazuron (TDZ) + 0.25 mg/l NAA. NAA at 1.25 mg/l was most efficient for maximum root induction (83.32%). In the present study, an effective protocol of carnation explants sterilization was optimized for successful callusing and shoot regeneration.