WPM Medium Research Articles

OPTIMIZATION OF THE HORMONAL STATUS OF THE CULTURE MEDIUM FOR H. RHAMNOIDES IN VITRO CULTIVATION

Sea buckthorn (Hippophae rhamnoides L.) is an ancient crop that has traditionally been used as a medicinal plant, health promotion agent and dietary supplement. The fruits of sea buckthorn, which are a source of carotenoids, which had been collected since ancient times and was introduced into cultivation only at the beginning of the 20th century. Currently, sea buckthorn berries are harvested on an industrial scale, as due to the high content of biologically active substances in them, consumer interest in sea buckthorn products has increased significantly, and their use in the food industry and medicine is expanding. Due to its biologically active compounds, high content of vitamin C, flavonoids, carotenoids and tocopherols, sea buckthorn is an excellent raw material for functional foods. The purpose of this work is to select conditions for cultivating explants of H. rhamnoides L. plants and obtaining micro-shoots for subsequent microclonal reproduction. The material for initiating a sterile culture was the seeds H. rhamnoides. The samples were introduced from natural populations in the RSE “Altai Botanical Garden” of the SC of MoES of the Republic of Kazakhstan (Ridder). Solutions of 0.1% sulema, 34% hydrogen peroxide, and 10% Domestos solution were used for seed sterilization, the exposure period was 20 minutes. Next, the seeds were planted on the surface of the WPM and ½ MS nutrient medium with the addition of phytohormones 6-benzylaminopurine (BA) and gibberellic acid (GA3) in various concentrations. Activated carbon in an amount of 2 g/l was used to reduce the accumulation of polyphenols in the medium. The beginning of germination was noted on days 7-8, depending on the genotype of sea buckthorn. The minimum number of infected seeds was observed in the variant using 0.1% sulema. When using hydrogen peroxide, the contamination of seeds with fungal and bacterial infections was at the level of 40.8-45.5%. The largest number of germinated seeds were observed when using WPM medium. The maximum values of seedling length were noted on WPM media with the addition of 1 mg/l BA + 1 mg/l GA3, where the average shoot length was 8.6±0.9 cm. In this variant, sterile seedlings were characterized by an intense green color and well-developed cotyledon leaves. In some genotypes, intensive growth and the appearance of a second internode were noted. In other variants, height indicators varied from 3.2 cm. up to 4.2 cm. Thus, we have found that WPM medium supplemented with 1 mg/l 6-benzylaminopurine and 1 mg/l gibberellic acid is better suited for obtaining sterile shoots from H. rhamnoides seeds. The obtained sterile seedlings of H. rhamnoides will be used in vitro culture for subsequent microclonal reproduction.

Research on the rapid tissue breeding technology of the endangered plant Cibotium barometz (L.) J. Sm.

Cibotium barometz (L.) J. Sm., a fern, holds significant value in traditional Chinese medicine. This research aimed to establish a rapid tissue breeding technology for Cibotium barometz (L.) and provide a theoretical basis for its artificial breeding and industrial planting. The optimum conditions for spores germination were selected, including both the best sterilization time and the ideal spore germination medium. Subsequently, the optimal medium for proliferation and differentiation were chosen, and the optimal concentration of plant hormones was screened to determine the optimal medium. The rooting experiment was performed in two single-factor experiments by using differentiated sporophytes as materials. These experiments showed that the optimal sterilization time was 11 min and the best medium for germination was 1/8MS + 0.02 mg/L IAA. MS medium was suitable for proliferation, while WPM medium was suitable for sporophyte differentiation. The best medium for growth was MS + 1.0 mg/L IAA + 0.5 mg/L 6-BA. In the absence of sucrose, the seedlings barely grew and failed to differentiate into sporophytes. They showed optimal growth and differentiation at a sucrose concentration of 20 g/L. The plant growth regulators plant growth regulators used, including IAA, NAA, 6-BA, and GA3, showed more effective differentiation, wherease KT had a slightly weaker effect. The rooting rate reached the maximum when the concentrations of ABT and IBA were at 1.5 mg•L− 1 and IAA was at 1.0 mg•L− 1. The IBA had a significant effect on the average and the longest root length, while the three PGRs had no obvious effect on the average or maximum diameter. Plant tissue culture seedlings still have good genetic stability after subsequent generation. In this study, the optimal cultivation conditions for rapid breeding technology in tissue culture, covering stages from germination and growth to differentiation and rooting, were obtained. Moreover, sporophytes were successfully transplanted to the external environment. This study provided a theoretical reference for the industrial planting of C. barometz.

Micropropagation of Vaccinium corymbosum L.‘Bluecrop’ in Rocker Temporary Immersion System (TIS) Bioreactor

Blueberries are high-value fruits. The traditional method of propagation by cuttings cannot supply the modern market with large quantities of seedlings. The method of micropropagation of plants in vitro makes it possible to bring the production of blueberry seedlings to the highest level. Blueberries have not been sufficiently studied in in vitro culture, so the search for the simplest and most cost-effective methods of micropropagation remains relevant. The problem of accelerated micropropagation of blueberries can be solved using rocker-type bioreactors, which differ from other models in terms of simplicity of design and low cost. A study was carried out to evaluate the effectiveness of micropropagation of Vaccinium corymbosum 'Bluecrop' in rocker bioreactors. Two types of bioreactors were compared: the bioreactor of the Platform system and the TIS rocker bioreactor modified by the author. As a control, blueberries were grown on a semi-solid medium. The effectiveness of blueberry micropropagation was evaluated by the following indicators: multiplication coefficient, shoot length, and proportion of vitrified shoots. Experiments were conducted on WPM medium, with zeatin supplementation at a concentration of 1.0 mg/l, resulting in optimal results. It is shown that the rocker bioreactor is slightly inferior to the plantform bioreactor in micropropagation but outperforms the method of micropropagation on semisolid media. The rocker bioreactor can be fully utilized for production purposes. In order to reduce costs and increase technical reliability, the working principle of the mechanical drive of the author's model of a rocker-type bioreactor was changed.

Plant regeneration capacity in seeds of three species of Miconia (Melastomataceae) may be related to endogenous polyamine profiles.

In plant tissue culture, differences in endogenous levels of species-specific plant growth regulators (PGRs) may explain differences in regenerative capacity. In the case of polyamines (PAs), their dynamics and distribution may vary between species, genotypes, tissues, and developmental pathways, such as sexual reproduction and apomixis. In this study, for the first time, we aimed to assess the impact of varying endogenous PAs levels in seeds from distinct reproductive modes in Miconia spp. (Melastomataceae), on their in vitro regenerative capacity. We quantified the free PAs endogenous content in seeds of Miconia australis (obligate apomictic), Miconia hyemalis (facultative apomictic), and Miconia sellowiana (sexual) and evaluated their in vitro regenerative potential in WPM culture medium supplemented with a combination of 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BAP). The morphogenic responses were characterized by light microscopy and scanning electron microscopy and discussed regarding the endogenous PAs profiles found. Seeds of M. sellowiana presented approximately eight times more putrescine than M. australis, which was associated with a higher percentage of regenerated calluses (76.67%) than M. australis (5.56%). On the other hand, spermine levels were significantly higher in M. australis. Spermine is indicated as an inhibitor of auxin-carrying gene expression, which may have contributed to its lower regenerative capacity under the tested conditions. These findings provide important insights into in vitro morphogenesis mechanisms in Miconia and highlight the significance of endogenous PA levels in plant regeneration. These discoveries can potentially optimize future regeneration protocols in Miconia, a plant group still underexplored in this area.

Micropropagação de Nolana intosa como ferramenta para sua domesticação e conservação

Abstract A complete protocol of Nolana intonsa I. M. Johnst, micropropagation was developed. The culture media used were WPM, DKW, and MS as control. DKW medium produced the best results over in vitro development of N. intonsa, generating a significant increase in the multiplication rate, lateral shoots formation, height, and general quality of the plantlets. In the case of fresh weight, dry weight, and water content, no differences were observed between MS and DKW, but a significant decrease in these parameters was produced when the WPM medium was used. Subsequently, when DKW was defined as basal medium, the effect of auxin supplementation was also evaluated. The addition of IBA generated a desirable effect over the in vitro plantlets. The addition of 0.05 mg L-1 of IBA improve the multiplication rate, the shoot's development, plant's height, and reduced in a significant way the damage to the plantlets. Fresh weight, dry weight, and water contents also showed a significant increase when IBA supplementation was added to the DKW medium. The plants where acclimatization of the plantlets was possible, obtaining finished pot plants capable of growth under greenhouse conditions. The development of a micropropagation protocol of N. intonsa could help the conservation and sustainable utilization of this endemic Chilean species.

Estabelecimento in vitro de Sideroxylon obtusifolium (Roem. & Schult.) T. D. Penn

ABSTRACT Sideroxylon obtusifolium is a native species recognized by traditional communities for its versatility, as it is used to treat various diseases, in fence construction, furniture manufacturing, and tool handles. It is also used for both human and animal consumption. However, extractive use combined with environmental impacts such as habitat loss and wildfires can cause a significant reduction in this species. Therefore, the adoption of biotechnological techniques such as plant tissue culture has been recognized as a significant resource to support the preservation of species with economic and medicinal importance and endangered. Thus, this study aimed to determine an efficient protocol for the in vitro establishment of S. obtusifolium. To achieve this, the seeds were disinfected using different chemical agents (carbendazim, chlorine dioxide, and sodium hypochlorite) for varying lengths of time to establish an efficient disinfection method. Additionally, MS ½ and WPM media, with and without the addition of activated charcoal, were tested to determine the most efficient medium composition for germination. The results indicated that sodium hypochlorite at 2% for 25 minutes was effective for seed asepsis. For germination, the most suitable medium was WPM containing activated charcoal, resulting in healthy and uniform seedlings that can serve as plant material for in vitro propagation of the species.

Use of rocker bioreactor for propagation of the Vaccinium corymbosum L.

Plant biotechnology has the potential to meet the market demand for a significant number of seedlings. The current state of the industry is characterised by exemplary results in the field of micropropagation, with notable achievements observed in the cultivation of diverse plant crops, particularly berries. Nevertheless, certain aspects of this technology remain imperfect at the industrial level. The multiplication of microshoots of berry crops remains a costly process. The transition of numerous laboratories from semi-solid agar medium to liquid has resulted in a reduction in the costs associated with propagation. However, the majority of standard bioreactors are costly and frequently challenging to maintain. In the present study, a rocker-type bioreactor system for micropropagation of blueberries was tested using Vaccinium corymbosum L. ‘Pink Lemonade’ as an example. In comparison to the traditional method of micropropagation on a gel medium, the rocker-type bioreactor demonstrates superior outcomes. The multiplication coefficient of blueberry shoots was found to be approximately twofold higher when the liquid WPM medium was supplemented with 0.2 mg/l zeatin within the bioreactor, in comparison to the control variant cultivated on a semi-solid medium of identical composition. The shoots obtained in the bioreactor successfully completed the stages of rooting and acclimatisation to post-aseptic conditions.

In vitro culture of nodal cuttings in kiwifruit

This study aimed to determine the effects of plant growth regulators and different medium on in vitro propagation of ˈHaywardˈ and ˈZespri Goldˈ kiwifruits. Micro-cuttings were used as explant sources and cultured in MS and WPM medium containing different concentrations of BA and GA3. Subcultures were carried out at intervals of 4-6 weeks. Contamination rate (%), blackening rate (%), callus development rate (%), shoot rate (%), and propagation coefficient (plantlet/explant) were determined. The micropropagation experiment was carried out according to the randomized plot design. The arc-sin transformation was applied to the percentage values before analysis. Significance levels of the means were compared with the LSD test. It was determined that 0.1% mercury chloride application increased the sterilization efficiency. As the BA concentration in the medium increased, the rate of callus formation of the explants increased. While there was no difference in shoot rates of explants cultured on MS and WPM medium, the propagation rate was higher in MS medium. The propagation coefficient of the ˈHaywardˈ kiwi cultivar was 3.08 in MS medium containing 1.0 mgL-1 BA + 0.5 mgL-1 GA3. MS medium can be recommended as a basic medium for in vitro kiwif propagation.

Respon Eksplan Buku Durian Lahung (Durio dulcis) terhadap Konsentrasi BAP (Benzil Amino Purin) pada Media WPM (Woody Plant Medium)

Lahung is a genus of endemic Durio in Kalimantan which currently has vulnerable status and is rare. Therefore, ex-situ conservation of this plant has begun using tissue culture techniques. Several things that need to be considered in in vitro propagation are the right type of explant, planting mediun and PGR. Stem nodes are generally chosen as explant because their availability does not depend on the season and has a fast response in bud induction. WPM medium is e medium intended for woody plants such as durian lahung. BAP is a PGR from the cytokinin group which is quite avtive and the most widely used. This research aimed to determine the best response of the durian lahung stem node culture to the BAP concentration on WPM medium. This research was designed using a rancomized block design (RBD) with one factor in the form of BAP concentration consisting of six levels, i.e. 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 ppm. Each experimental unit was repeated four times and consisted of ten planting bottles for e total of 240 planting bottles. The variables observed were the percentage of live explant aged 1-8 WPP, callus growth time, percentage of explant forming callus aged 1-8 WAP, callus and texture callus, shoot growth time and number of shoots. The results showed that callus appeared in response of the durian lahung stem node to the BAP concentration treatments.

Fruit and Seed Morphometry and in Vitro Germination of Hollyhock Seeds

Alcea rosea L. is an ornamental shrubs that has many possible uses, including medical purposes. This species is mainly propagated by seeds, however, there are few studies that describe their morphometric characteristics, in addition, previous reports show that they have dormancy that makes the germination difficult. Therefore, this work aimed to determine the morphological characteristics of the fruit and seeds of A. rosea and to evaluate its in vitro seeds germination under different pregerminative methods in different culture media. For the morphological description, 25 fruits or seeds were evaluated. For the in vitro germination in the MS and WPM culture media, the pregerminative treatments were: T1 - untreated seeds (control); T2 - mechanical scarification (cut in the seed coat); T3 - thermal scarification (immersion of the seeds in water at 60 ºC for 16 min). The experimental design was completely randomized, in a 3x2 factorial scheme (pregerminative treatments x culture media), with eight replications and twenty seeds per replication. A visual scale was proposed to classify the seedlings vigor. The schizocarp hollyhock fruit is flattened and its diameter is greater than its height, and each fruit contains 33 seeds, on average. The seeds have approximately 4.2 mm in length and 100 seeds weight, on average, 0.89 g. The culture medium does not influence the seeds germination and the pregerminative treatments are not necessary for the germination. However, the mechanical scarification promoted the best germination speed index and the production of more vigorous plants.

The Response of Moringa oleifera Lam. Nodes to Multiply on MS and WPM Media Supplemented with Different Concentrations of BA and Kin

The study was conducted at the laboratory of Plant Cells and Tissue Culture/Department of Forestry Sciences in the College of Agriculture and Forestry/the University of Mosul, during the year 2021-2022 AD on Moringa oleifera Lam. to spread the In vitro propagation. The effect of the type of nutrient medium (MS and WPM) and the type of cytokinin 6-Benzyladenine (BA) at the concentrations (0, 0.25, 0.5, 0.75, 1) mg.l−1 and Kinetin (Kin) at concentrations (0, 1, 2, 3, 4) mg.l−1 In the growth and multiplication of single nodes prepared from seedlings at 21 day. After eight weeks of cultivation, the results showed that there was a significant effect of the type of nutrient medium on the growth and multiplication of single nodes, as the MS medium was superior to the WPM medium in the number of shoots and leaves per single node. The best result was (6.4 and 4.7 shoot/node and 34.5 and 27.3 leaf/node) on the leaves, respectively, BA was also significantly superior to Kin in the number of shoots and the number of leaves per node which achieved (10.4 and 2.7 shoots/node and 52.1 and 19.5 leaves/node), respectively. On the other hand, the interaction (0.75 mg.l−1 BA with 4 mg.l−1Kin) in MS media caused the highest rate of the number of shoots and number of leaves achieved (19.6 shoots/node and 82.9 leaves/node), respectively.

Morphogenesis features of <i>Hedysarum alpinum</i> L. in <i>in vitro</i> culture

The plants of Hedysarum alpinum L. in the North are characterized by a long pregenerative period, the laboriousness of seed propagation, low field germination of seeds, rare self-sowing, and the impossibility of vegetative propagation. In connection with this, it seemed relevant to introduce this rare species (included in the Red Book of the Komi Republic) into aseptic culture to preserve and maintain the gene pool, as well as to further develop the technology of its cultivation to obtain medicinal raw materials. The morphogenesis was studied, and the peculiarities of the regeneration of adventitious shoots of Hedysarum alpinum in in vitro culture were revealed. During three subcultivations, the influence of two cytokinin growth regulators, 6-benzylaminopurine (BAP) and kinetin (KIN), at concentrations from 0,5 to 1,0 mg/l, on the regeneration potential of different explants of Hedysarum alpinum in in vitro culture was determined on the WPM environment. A high frequency of regeneration of shoots from single-node segments and cotyledon nodes was obtained 79% and 65%, respectively. In the second and third passages, there was an increase in the regenerative activity of the cotyledon node explants and an increase in the multiplication factor to 5 shoots per explant. It was shown that relatively high concentrations (1,0 mg/l) of BAP and CIN increase the number of shoots per explant but inhibit their growth and development. For the reproduction stage proper, the medium containing BAP 0,5 + CIN 0,5 + IAA 0,1 mg/l is optimal. It was shown that the initiation of rhizogenesis actively took place on the WPM medium supplemented with IAA 0,5 and IBA 0,5 mg/l, on which the proportion of rhizogene explants was 77%. The maximum values for the length and number of roots were obtained on the medium with IAA 1,0 mg/l and with the combined use of two auxins (IAA with IBA at 0,5 mg/l). The regenerated plants were transplanted into non-sterile conditions, and their survival rate under ex vitro conditions was 50%.

Effects of parental genotypes on embryo rescue of seedless grape hybrid

ABSTRACT The success of seedless grape embryo rescue depends on many factors. To study the effects of parental genotypes on embryo rescue, we conducted 11 hybridisation combinations using nine stenospermocarpic seedless grapes as female parents and three seedless or seeded grapes as male parents. At the optimal sampling time of each mother plant, the hybrid ovules were inoculated and cultured on a solid–liquid biphasic MM3 medium. Then, the bare embryos were removed and inoculated on a WPM medium for germination and seedling formation. The results showed that when ‘Jupiter’ (seedless) was the male parent, ‘Perlette’ had the highest rates of embryo development, germination and seedling formation, followed by ‘Kunxiang Seedless’; when ‘Su-67’ (seedless) was the male parent, ‘FZ42’ had the highest embryo development rate; when ‘Beichun’ (seeded) was the male parent, ‘Fresno Seedless’ had the best embryo rescue results, followed by ‘Qinhong No.10’. These suggest that ‘Perlette’, ‘Kunxiang Seedless’, ‘Fresno Seedless’ and ‘Qinhong No.10’ are suitable female parents for embryo rescue. When ‘FZ42’ was the female parent, ‘Su-67’ was better than ‘Jupiter’ as the male parent; when ‘Perlette’ was the female parent, ‘Jupiter’ and ‘Su-67’ as male parents had no significant difference, indicating that paternal genotype has a certain effect on embryo rescue. HIGHLIGHTS The maternal genotype has a significant effect on the embryo rescue of seedless grapes. The paternal genotype has a certain effect on embryo rescue of seedless grapes. ‘Perlette’, ‘Kunxiang Seedless’, ‘Fresno Seedless’ and ‘Qinhong No.10’ are suitable female parents. A total of 345 hybrids from 11 cross-combinations were obtained by embryo rescue.

GERMINATION IN VITRO OF SEEDS OF A THREATENED ARBOREAL SPECIE IN THE MUNICIPAL DISTRICT OF ABAÍRA (BA)

The aim of the present study was to evaluate the effect of culture media and disinfestation treatments on germination and the contamination in vitro of Zeyhera montana seeds. The trial was comprised of two experiments: in the first, the seeds were surface sterilized with alcohol 70% (1 min) + NaOCl 0.25, 0.5 or 1% active chlorine (5 or 10 min). The seeds were placed in flasks containing MS, MS rooting, Knudson B, Knudson C, Agar or WPM culture media. In the second experiment, the seeds were inoculated on the culture media which showed the best results in the previous experiment. Germination was slow and disuniform. The best results were 75% and 40% germination on Knudson C and MS rooting media, respectively.

Dormancy break induced by gibberellic acid and in vitro germination of seeds and zygotic embryos of Prunus campanulata Maxim

Prunus campanulata is a species largely adopted for landscape composition in Brazil with limited seedling production by seed dormancy, lacking studies about in vitro propagation. This study aims to evaluate different P. campanulata seed pretreatments on germination, and the effect of GA3 on dormancy break and seedlings biometry. Seeds were processed in three treatments: complete seeds, seeds without endocarp, and isolated zygotic embryos incubated in a WPM medium containing different GA3 concentrations (0.0, 2.0, and 4.0 mg L-1). After 30 days of in vitro incubation were evaluated the germination percentage, mean germination time, percentage of normal seedlings, percentage of seedlings with leaves, and survival percentage were. Seedlings greater than 3.0 cm were selected for ex vitro adaptation, evaluating after 32 days the biometric variables: total length, aerial part length, root length, and the number of leaves. Complete seeds do not germinate, suggesting dormancy associated with the endocarp, whereas seeds without endocarp and isolated zygotic embryos showed the same germination rate, with no effect on GA3. The GA3 promoted greater seedling growth at concentrations between 1.89 mg L-1 for the total length of the isolated zygotic embryo and 2.24 mg L-1 for the length of the aerial part of seeds without endocarp. In conclusion, seed processing, i.e., removing the endocarp or isolating the zygotic embryo can overcome dormancy, improving germination and seedling production of P. campanulata in vitro.

Somatic Embryogenesis Induction and Genetic Stability Assessment of Plants Regenerated from Immature Seeds of Akebia trifoliate (Thunb.) Koidz

Akebia trifoliata is a perennial woody plant with considerable potential in nutrition, food, and health, and the production of seedlings with high quality is critical for its economic utilization. Plant regeneration through somatic embryogenesis is a powerful alternative for propagating many plant species. In this study, a simple and practicable protocol was developed for plant regeneration from immature seeds of A. trifoliata via somatic embryogenesis, and the genetic stability of regenerated plants was also assessed. In the somatic embryo (SE) induction stage, the highest frequency of somatic embryogenesis (35.2%) was observed on the WPM medium containing 1.0 mg L−1 of thidiazuron (TDZ) and 1.0 mg L−1 of 6-benzyladenine (6-BA). The concentration of 6-BA was optimized at 1.0 mg L−1 for the proliferation and maturation of the induced SEs, and the combination of 2.0 mg L−1 of indole-3-butyric acid (IBA) and 0.5 mg L−1 of TDZ was the most responsive for root development and plant growth. The leaf morphological characteristics greatly varied among the established plants, and they could be grouped into three plant types, namely the normal type, Type Ι, and Type ΙΙ. Remarkable differences in the number, size, shape, and color of the leaflets were observed among the three types, while their ploidy level was the same via flow cytometry analysis. The Type ΙΙ and the Type Ι plants had the highest and the lowest net photosynthesis rate, transpiration rate, and stomatal conductance among the three groups, respectively, and both had a smaller size of stomatal guard cells than the normal type. Simple sequence repeat (SSR) analysis detected that 41 bands (43.62%) were different from those observed in the wild, indicating a high degree of polymorphism between the regenerants and their donor parent. The obtained plants might hold potential for future genetic improvement and breeding in A. trifoliata, and the established regeneration protocol might serve as a foundation for in vitro propagation and germplasm preservation of this crop.

Investigation of Growth Factors and Mathematical Modeling of Nutrient Media for the Shoots Multiplication In Vitro of Rare Plants of the Rostov Region

Micropropagation is an effective way to preserve the gene pool of threatened plants. This study is devoted to the mathematical modeling of nutrient media and the study of the effect of mT (meta-topoline) on the multiplication of shoots of Hedysarum grandiflorum, Hyssopus cretaceus, and Matthiola fragrans in vitro in comparison with benzylaminopurine (BAP) and kinetin (KT). Initiation was performed on an MS medium with 0.5 mg/L BAP. For shoots multiplication, MS, B5, and WPM media were used with the addition of mT, BAP, KT. For H. grandiflorum, the multiplication coefficient of shoots was highest on medium B5 with the addition of mT at a concentration of 1 mg/L—2.90 shoots per plant, for H. cretaceus—B5 + 0.5 mg/L mT, and for M. fragrans—B5 + 1 mg/L KT. A positive effect of mT on H. grandiflorum and M. fragrans in vitro was found. The efficiency of using KT for H. cretaceus shoot multiplication is shown. The effectiveness of the B5 nutrient medium for H. grandiflorum and M. fragrans was determined. The positive effect of WPM for H. cretaceus micropropagation has been demonstrated. It is not recommended to use the MS media for micropropagation of these plant species.

Effect of <i>seed priming</i> with NaCl on the induction of salinity tolerance in <i>Myracrodruon urundeuva</i> Allemão <i>in vitro</i>

Soil salinization is an environmental factor that frequently occurs in semi-arid regions around the world and seed priming technique is one of the alternatives to obtain the greatest establishment of seedlings in the field, through the induction of tolerance to environmental stresses. This research aimed to evaluate the effect of seed priming with NaCl on the induction of salinity tolerance in Myracrodruon urundeuva Allemão in vitro. The research was carried out at the Center for Strategic Technologies of the Northeast, in Recife / PE-Brazil M. urundeuva seeds were disinfected and submitted to two treatments: water (control) or NaCl (2mM), and inoculated in WPM medium at three saline concentrations (0.0; 25.0 and 50.0 mM NaCl) for 45 days. Plant height, number of leaves, fresh biomass (total, shoot, and root), shoot/root ratio, sodium and potassium and Na/K ratio, antioxidant enzyme activity, and peroxide content were evaluated malondialdehyde hydrogen. The data were subjected to variance analysis and the results were compared using the Student-Newman-Keuls test at 5% probability, using the R software. Seed priming with NaCl promoted a beneficial effect on the height of seedlings exposed to salinity. On the other hand, height was inversely proportional to saline concentrations, regardless of seed priming. The shoot/root ratio was also lower in seedlings cultivated under 25 and 50 mM NaCl. Despite being favorable for most growth variables, seed priming with NaCl induced an increase in lipid peroxidation in seedlings that were not exposed to salinity, which is linked to a decrease in the activity of antioxidant enzymes. The antagonistic response to NaCl stimulation between growth parameters and plant defense observed in the present research raises the need for further complementary studies that make it possible to delineate the metabolic alterations of M. urundeuva against a chemical stimulus to induce tolerance to a given stress.

Effects of pre-bloom spraying thidiazuron and different embryo development media on seedless grape embryo rescue

ABSTRACT Embryo rescue technology has been widely applied in seedless grape breeding, but its success depends on many factors. Here, two Vitis vinifera seedless varieties ‘Qinhong No.2’ and ‘Qinhong No.10’ were used as research objects, the inflorescences were sprayed with 0.5 mg·L−1 thidiazuron 10 days before flowering, and then the ovules from open- and self-pollination of them were cultured in solid–liquid biphase MM3 media to investigate the effect of thidiazuron on embryo rescue. Under natural condition, the ovules of open- and self-pollination were inoculated onto three solid–liquid biphase media NN, ER, and MM3 to compare the efficiency of embryo rescue. The results showed that pre-bloom spraying thidiazuron significantly promoted ovule development and further improved the effect of embryo rescue in vitro. After applying thidiazuron, the embryo development rate, germination rate, and seedling rate of the four combinations reached 30.77%–42.62%, 29.36%–41.64%, and 22.02%–40.33%, respectively. Open-pollination of the two varieties provided better effects for culturing than their self-pollination, and the MM3 medium was always more suitable for embryo development than either the ER or NN medium. Furthermore, the germination rate of bare embryos of ‘Qinhong No. 10’ open-pollination on solid WPM medium surpassed that of ovules (without embryo stripping) on solid NN medium. HIGHLIGHTS Pre-bloom spraying TDZ could improve the effect of embryo rescue of seedless grape. The embryo rescue effect was better in open- than self-pollinated seedless grapes. Solid–liquid biphase MM3 was more suitable for embryo rescue than an ER or NN medium. The seedling rate of bare embryos on WPM medium exceeded that of ovules on NN medium. Overall, 2312 hybrids from the four combinations were obtained via embryo rescue.

Effect of Actisil (Hydroplus™), organic supplements, and pH of the medium on the micropropagation of Vaccinium corymbosum

The effect of commercial Hydroplus™ Actisil, coconut water, coconut milk, and pH of the WPM mediumon the micropropagation of V. corymbosum ‘Liberty’ was studied. Three experiments were performed withdifferent concentrations of silicon Hydroplus™ Actisil (Si), coconut water (CW), coconut milk (CM), anddifferent pH as a stress factor. Si was applied at a concentration of 50, 100, 200 and 500 mg dm–3. The highest explant (2.02 cm) with the highest number of new shoots (1.91) and fresh weight (55.16 g) was obtained on WPM medium with the addition of Si in concentration 200 mg dm–3. In experiment 2, similar to 0.1 mg dm–3 zeatin explant growth was achieved when 15% CW was added to the WPM medium (2.13 cm). The use of CM did not have a positive effect on blueberry growth in vitro. The results of experiment 3 indicated that explants of blueberry better developed when pH was lower (5.0) with the highest number of new shoots (2.85) and fresh weight (95.67g). However, there were no significant differences in plant height between pH used. The application of 200 mg dm–3 Actisil benefits the negative effect of higher pH of the WPM medium on micropropagation of blueberry in case of plant height, fresh weight, and biochemical parameters (proline, malondialdehyde – MDA and catalase – CAT activity).