Abstract
Amorphophallus konjac (Araceae) a perennial herb, it has high medicinal and industrial value. In this study, a simple and efficient system for direct somatic embryogenesis and plantlet regeneration of Amorphophallus konjac was developed. The floral axis was used as the experimental material. The primary callus, developed from the floral axis grown on Murashige and Skoog (MS) medium supplemented with different hormone combination at different concentrations. The highest rate of embryogenic callus formation was observed on the MS medium containing 9.04 µM 2, 4-dichlorophenoxyacetic acid (2, 4-D) and 5.37 µM naphthalene acetic acid (NAA). The maximum induction rate was 79.8%, and the embryogenic calli were able to subculture on a medium containing similar hormone combination for over 1 year. The calli were also placed on different media for regeneration and it produced complete plants with shoots and root systems simultaneously. The highest differentiation rate of the embryogenic calli grown on differentiation medium supplemented with 8.88 µM 6-benzylaminopurine (6-BA) and 5.37 µM NAA was 95.6%. Flow cytometry analysis showed no ploidy variation in all the regenerate plantlets.
1 Introduction
Amorphophallus konjac (Araceae) belongs to a group of perennial plants characterized by tubers and pinnately compound leaves. This species is widely distributed throughout Southwest Asia and Africa [1,2], and has been used for a long time as a medicinal plant. A. konjac is also utilized for pharmaceutical, chemical industries as well as in agriculture and food source because its tuber contains a high level of water-soluble glucomannan [3]. Although A. konjac demonstrates a great potential for commercial application and offers favorable economic benefits, the poor disease resistance and low-efficiency propagation of A. konjac are hindering its production.
Plant tissue culture technology has been applied to produce healthy seeds and seedlings for many crops, such as potato, corn, and wheat. Apparently, the tissue culture technique could be an important and efficient method to solve the problem in the A. konjac industry. Many studies on A. konjac tissue culture have been reported. These studies used different explants from A. konjac, such as shoot tip and bud [4], anther, corm, leaf, root [5] side-bud, subcutaneous tissue, main-bud, basilartissue, budlet [6], petiole [7], and unpollinated ovaries [8]. In addition, the A. konjac plant regeneration of these studies was almost developed from organogenesis instead of somatic embryogenesis. Plant regeneration during somatic embryo genesis offers certain advantages over organogenesis, given that embryos contain both root and shoot meristems. Somatic embryos are single cells and clonal in origin. Somatic embryogenesis is a powerful tool for genetic improvement of any plant species [9]. Somatic embryogenesis is defined as a process in which a bipolar structure, resembling a zygotic embryo, develops from a non-zygotic cell without vascular connection with the original tissue [10]. In addition, in most cases the somatic embryos or the embryogenic cultures can be cryopreserved, which makes it possible to establish gene banks. Embryonic cultures are an attractive target for genetic modification. [11]. It is also an efficient method for clonal propagation of genetically stable regeneration in many species [12]. However, the induction of somatic embryogenesis in A. konjac is rarely reported worldwide. Hu [7] found that the Murashige and Skoog (MS) medium supplemented with high concentration of auxin alone with of 13.57 μM 2,4-dichlorophenoxyacetic acid (2, 4-D) and 8.88 μM 6-benzylaminopurine (BA) or 21.48 μM naphthalene acetic acid (NAA), and 6.66 μM 6-BA can be used for somatic embryo induction, but no plantlets were regenerated.
We have developed an efficient method for somatic embryogenesis from floral axis of A. konjac. This system will not only improve the production of healthy seed tubers but also contribute to transgenic and functional genome researches on A. konjac.
2 Methods
2.1 Plant materials and culture conditions
Amorphophallus konjac flower buds were gathered from the greenhouse of Life Science College of Wuhan University in China. The floral axes were cut off as the explants for the further treatment. The explants were cut into pieces, surface sterilized with 75% ethyl alcohol for 30 s followed by 0.1% (w/v) HgCl2 for 6-8 min with occasional shaking, and then rinsed thoroughly at least thrice with sterile distilled water. The floral axes were cut into small pieces (approximately 1cm × 1cm) by a sterile knife; 2-3 pieces were placed in 250 ml jars containing 50 ml of medium with various concentrations of plant hormones. These various combinations were used to test the callus induction (Table 1).
Effect of different concentrations of 2, 4-D, 6-BA and NAA on embryogenic callus induction of A. konjac on MS medium
| Growth regulators (µM) | Frequency of explants with embryogenic callus produced (%) | ||
|---|---|---|---|
| 2, 4-D | 6-BA | NAA | |
| 0 | 0 | 0 | 0 | 
| 2.26 | 10.23 ± 1.63cd | ||
| 4.52 | 2.43 ± 0.47ab | ||
| 9.04 | 0 | ||
| 0 | 2.22 | 2.5 ± 0.42ab | |
| 2.26 | 2.22 | 30.20 ± 1.73gh | |
| 4.52 | 2.22 | 33.33 ± 1.93hi | |
| 9.04 | 2.22 | 35.57 ± 1.13i | |
| 0 | 4.44 | 11.37 ± 1.38d | |
| 2.26 | 4.44 | 33.33 ± 1.93hi | |
| 4.52 | 4.44 | 43.67 ± 2.23j | |
| 9.04 | 4.44 | 26.30 ± 0.40fg | |
| 0 | 8.88 | 5.60 ± 1.27bc | |
| 2.26 | 8.88 | 35.57 ± 1.13i | |
| 4.52 | 8.88 | 49.23 ± 2.05k | |
| 9.04 | 8.88 | 46.67 ± 1.93jk | |
| 0 | 2.69 | 3.47 ± 0.50ab | |
| 2.26 | 2.69 | 17.80 ± 1.10e | |
| 4.52 | 2.69 | 24.43 ± 1.13f | |
| 9.04 | 2.69 | 45.57 ± 1.13jk | |
| 0 | 5.37 | 7.50 ± 0.49bcd | |
| 2.26 | 5.37 | 48.87 ± 5.57k | |
| 4.52 | 5.37 | 71.10 ± 1.10m | |
| 9.04 | 5.37 | 79.80 ± 1.10n | |
| 0 | 10.74 | 11.70 ± 0.87d | |
| 2.26 | 10.74 | 45.17 ± 1.00jk | |
| 4.52 | 10.74 | 58.47 ± 0.61l | |
| 9.04 | 10.74 | 62.50 ± 0.96l | 
Values represent the mean of three replicates ± SE. Mean values in a column followed by the same superscript are not significantly different (P = 0.05) based on Duncan’s multiple range test (DMRT).
The explants cultured in the culture bottles with MS (Murashige and Skoog, 1962) medium supplemented with 3% sucrose, 0.2% polyvinyl pyrrolidone and 0.3% phytagel (Sigma) and containing various combinations of plant hormones. The pH of each medium was adjusted to 5.8 by using 0.1 M HCl and 0.1 M NaOH; each medium was then autoclaved at 121°C and 1.2 kg·cm-2 pressure for 20 min. The cultures were incubated in the dark before being put under cool-white fluorescent light (12 h photoperiod and 50 μmol m-2 s-1 irradiance) and then maintained at 28 ± 2°C and 60% relative humidity.
Induction of somatic embryogenesis and plantlet regeneration
The explants were transferred into a fresh induction medium every 2 weeks until the somatic embryos were induced. The embryogenic calli were then detached from the explants. Some of embryogenic calli were subcultured on the primary medium to keep multiplying and maintained under the same conditions. The remaining embryogenic calli were transferred to the regeneration medium (Table 2). Each treatment was replicated thrice.
Effect of auxins (6-BA and NAA) and their concentrations on differentiation of embryogenic callus
| Growth regulators (µM) | Differentiation rate of embryogenic callus (%) | |
|---|---|---|
| 6-BA | NAA | |
| 0 | 0 | 0 | 
| 0 | 5.37 | 42.57 ± 4.45e | 
| 0 | 10.74 | 16.93 ± 0.69c | 
| 4.44 | 0 | 8.87 ± 0.81b | 
| 4.44 | 5.37 | 58.10 ± 0.70f | 
| 4.44 | 10.74 | 59.77 ± 1.5f | 
| 8.88 | 0 | 23.73 ± 0.23d | 
| 8.88 | 5.37 | 95.63 ± 0.73g | 
| 8.88 | 10.74 | 47.13 ± 1.59e | 
Values represent the mean of three replicates ± SE. Mean values in a column followed by the same superscript are not significantly different (P = 0.05) based on Duncan’s multiple range test (DMRT).
2.2 Histological analysis
The calli were obtained for histological examination. The samples were fixed in FAA (formaldehyde/acetic acid/ ethanol=10:5:85 v/v/v) for 48 h, followed by 30 min of dehydration at increasing ethanol gradations [25, 50, 75, 95, 100% (v/v)]; dehydration was performed twice for each step. Ethanol was replaced by gradual dilution with trichloroethane solution. The specimens were infiltrated in a vessel that contained the paraffin wax and kept at 56°C for at least 24 h; finally, the samples were embedded in the paraffin wax. The samples were sectioned into 10 µm-thick slices using a rotary microtome (AO 820, Scientific Instruments) and then mounted on glass slides. The sections were dewaxed in xylene for 5-10 min, stained with Heindenhain’s hematoxylin, mounted using a drop of neutral balsam, and covered by the coverslips before examination under a Nikon ANTI-MOULD microscope (15×40).
2.3 DNA ploidy analysis
Flow cytometry analysis was performed to determine the ploidy level of the regenerated plants by using the leaves of randomly selected 21-month-old regenerated plantlets. The leaves of the mother plant were used as control. Flow measurement was performed as described by [13].
To determine the nuclear DNA content, flow cytometric analysis was performed using the protocol of Arumuganathan and Earle [14] at a laser wavelength of 488nm. Briefly, a sharp razor blade was used to manually scrape the young leaf tissues (typically 30 mg) on ice in 1.5 ml of nucleus extraction buffer containing 5.55 mg of KCl, 3.69 mg MgSO4, 1.8 mg of Hepes, 1.5 mg dithiothreitol, 36.3 µl of 10% Triton X-100 and a little of 5% polyphenol oxidase, which helps prevent polyphenol oxidation in the sample. The nuclear suspensions were filtered through a 30 µm mesh nylon cloth and then placed into a labeled test tube. Following filtration, supernatant was aspirated by centrifuged at 3000 rpm at 4°C for 15 min, and nuclei were resuspended in 450 µl MgSO4·buffer containing 5.55 mg KCl, 3.69 mg MgSO4, 1.8 mg of Hepes and 50 µl RNase A (50 µg/ml) was added to prevent staining of double-stranded RNA. The suspension was subsequently stained with 5 µl of propidium iodide and then incubated in the dark for 15 min at 37°C.
2.4 Statistical analysis
The experiments were set up in a completely randomized design with three replicates for each treatment and each replicate included 10 explants. The number of tissue clumps showing embryogenesis in each petri dish was counted, and percentage induction was calculated as the ratio of the number of clumps showing embryogenesis to the number of total clumps and then expressed as percentage. The data were analyzed using one-way analysis of variance (ANOVA) and the significance of the differences among treatments of each experiment was evaluated by Duncan’s multiple range test at P = 0.05 using SPSS (version 16.0).
3 Results
During the first few days of culture, some small pieces of floral axes swelled and folded on the MS medium supplemented with different hormone combination of various concentrations. Approximately 4 weeks later, the embryogenic calli were obtained from the cut edges of most pieces (Figure 1), these calli formed directly from the explants without an intervening callus phase and can be easily distinguished from the explants’ surface. The calli were induced by all combinations of auxin and cytokinin, although induction percentage varied significantly depending on the hormone combinations. Nearly no callus was induced in hormone-free medium.

Embryogenic calli induction from explants
Induction percentage (%) in different concentrations is presented in Table 1. The optimum callus induction was observed on MS medium supplemented with 9.04 µM 2, 4-D and 5.37 µM NAA among all other auxins and cytokinins combinations and concentrations used. The corresponding highest induction rate was approximately 79.8%. The calluses on this type of medium were friable, semi-transparent and yellowish (Figure 2). In addition, histological examination showed the regularly arranged cells of the callus, and each developmental process of the callus can be observed in the microscopic field (Figure 3). Transferring the compact calli to the differentiation medium resulted in morphogenetic events. Typical features of meristemoid (cluster of organgenic cells) were small in cell size with cytoplasmic density, minimal vacuoles and relatively large nuclei.

Embryogenic callus multiplication

Histochemical analysis during the initiation of the somatic embryogenesis in A. konjac. a Initial phase of proembryo formation with densely stained meristematic cells indicating intensive cell divisions. b Globular embryo (arrow) clearly discernible from the surrounding tissue c Heart-shaped embryo stage. d Further differentiation of heart-shaped resulted in the formation of torpedo stage.
After approximately 25 days, some of the embryogenic calli began to differentiate, part of the calli turned green and small bud-like structure gradually formed (Figure 4a) on the differentiation culture medium containing various concentrations of NAA and 6-BA. Over the subsequent week, the buds could be observed clearly, their numbers increased rapidly and their height increased was visible (Figure 4b). Approximately 40 days later, most of the calli developed into 3.0-5.0 cm long plantlets bearing well-formed roots (Figure 4c). The highest rate of differentiation is 95.6% (Table 2), and the medium supplemented with 8.88 µM 6-BA, 5.37 µM NAA was the most suitable to support normal development. In some differentiation medium, the calli differentiated into malformed buds or took roots only. These calli cannot develop into complete plantlets, almost all of them were dead ultimately. Alteration in the concentrations of the hormones keeping ratios constant remarkably decreased the percentage of differentiation. Few regenerated plantlets were observed in hormone free medium.

The differentiation of embryogenic calli. a Small bud-like structure formed from the calli. b Shoot proliferation from the calli gradually. c Approximately 40 days later, the calli developed into plantlets bearing well-formed roots.
The flow cytometry results shown in Fig. 5 strongly indicate that the analyzed regenerated plants were diploid and all the samples analyzed have the same ploidy level. No polyploidy occurred when somatic embryos were germinated and converted to plantlets.

Flow cytometer analysis of DAPI stained nuclei of A. konjac. Each flow cytometric analysis of the somatic embryo-obtained plants along with the parent grown showed that they all had same peaks.
4 Discussion
Somatic embryogenesis is a complex method of plant regeneration which can be affected by numerous factors: the genetic background of plant material, the manipulation of primary explants initiating culture and culture conditions [12]. Some studies have reported that the culture medium exerts stronger effect on somatic embryogenesis than other factors [15]. The type of hormone used, as well as the corresponding concentration, also significantly influences callus induction. In some plant species, 2, 4-D is the most effective auxin for somatic embryogenesis [16,17], whereas high Cytokinin in concentrations are required to initiate somatic embryogenesis in another species [18]. Our results show that somatic embryogenesis slightly occurred in media containing NAA or 6-BA, whereas embryogenic callus was induced much faster and more frequently when 2, 4-D was used, suggesting that floral axis was much more sensitive to 2, 4-D than to NAA and 6-BA. However, higher concentrations of 2, 4-D could not increase the induction rate nor stimulate callus development. Instead, high concentrations of 2, 4-D can result in soft, slow-growing, and malformed callus cultures, which will eventually turn brown/black [19]. A similar trend was also observed in 6-BA and NAA. Some researchers have reported that most species exhibit a lower frequency of primary than secondary somatic embryos induction [20,21]. Similar results are obtained in the present study.
We also found that the protocol developed by Pinto [22] combined a simple methodology with a low-hormone method reducing the risk of somaclonal variation. Our results strongly indicated that all the samples analyzed exhibited the same ploidy level and that no polyploidy was observed in embryogenic callus tissue. The stability reported here is not described in other species, in which polyploidisation was found during somatic embryogenesis (23-27). Endemann [27] found that tetraploidy occurs 8% of the clones tested over a culture period of 7 years in Quercusrobur. In Q. canariensis, tetraploidy occurred in somatic embryogenesis after 14 months of continuous subculture [23]. Prolonged culture, any unfavorable condition or any substance that affects or blocks plant metabolism, growth or development may result in polyploidization [27].
Somatic embryos are used for studying regulation of embryo development, but also as a tool for large scale vegetative propagation. In some cases, somatic embryogenesis is favored over other methods of vegetative propagation because of the possibility to scale up the propagation by using bioreactors. In grapevine (Vitis vinifera L.) cultivars, the maximum rates of induction and germination were 99.5% and 68%, respectively [28]. Pavlović [29] reported that the highest frequencies of embryogenic calli induction in cabbage (Brassica oleracea var. capitata) and cauliflower (Brassica oleraceavar. botrytis) were 83.3% and 87.5%, correspondingly. Moreover, the development of somatic embryos into plantlets was 56% in cabbage and 79% in cauliflower. Hence, the induction and differentiation rate in these species can satisfy the production needs. A study showed that unpollinated ovaries and petiole of A. konjac can be used as explants to induce development of embryogenic callus. But the embryogenic callus induced from the petiole cannot display normal development, and no plantlets are regenerated except that some adventitious buds have formed [7]. When unpollinated ovaries were utilized as explants, the rate of embryogenic callus induction was 34%, and the highest plantlet formation efficiency was only 35.5%, both of which are too low to be applied in A. konjac production [8]. It is the only report to date that obtains somatic embryogenesis of A. konjac. Given that the reported frequency of somatic embryogenesis is extremely low [7], we developed an efficient and reproducible tissue culture method for A. konjac. This method successfully induced the development of A. konjac embryogenic callus, which developed into healthy virus-free plantlet sex habiting a high percentage of acclimatization and slight ploidy variation. The entire regeneration procedure, including the acclimation period, took approximately 5 months and the recurrent somatic embryogenesis of A. konjac retained high embryogenic potential after 1 year.
Our findings will provide guidance for the practical and rapid propagation of A. konjac. It has proven that the floral axis is a better explant than the unpollinated ovaries and the petiole thus could be further applied in rapid propagation for production, with a comparatively high induction rate of 79.8% and differentiation rate of 95.6%, respectively. Moreover, the tuber of A. konjac is rich sources of water-soluble glucomannan, and widely used in industry. However, the floral axis is hardly used as industrial material. In conclusion, the floral axis is an ideal explant for induction of somatic embryogenesis and planet regeneration in A. konjac. The present study described a high-efficiency method for repetitive somatic embryogenesis for A. konjac by using floral axis as explants which is the most efficient so far. The efficient method for induction of primary and plant regeneration described in present study may contribute to the improvement of the propagation rate of A. konjac, which is useful in production. Therefore, based on this achievement, genetic improvement and application on breeding could be realized easily.
Acknowledgments
This study was supported by grants from the National Science and Technology Supporting Program (No. 2011BAD33B03), the Fundamental Research Funds for the Central Universities (No. 2042016kf1106)) and Philanthropic Project of Scientific Research of Hubei (No. 2012DBA11001).
Conflict of interest: Authors state no conflict of interest.
Abbreviations
- MS
 Murashige and Skoog medium
- NAA
 Naphthalene acetic acid
- 6-BA
 6-benzylaminopurine
- 2, 4-D
 2, 4-dichlorophenoxyacetic acid
References
[1] Hetterscheid W, Ittenbach S., Everything you always wanted to know about Amorphophallus, but were afraid to stick your nose into, Aroideana., 1996, 19, 7-131.Suche in Google Scholar
[2] Chua M, Baldwin T C, Hocking T J, et al., Traditional uses and potential health benefits of Amorphophallus konjac K. Koch ex NE Br, Journal of Ethnopharmacology., 2010, 128: 268-27810.1016/j.jep.2010.01.021Suche in Google Scholar
[3] Cescutti P, Campa C, Delben F, et al., Structure of the oligomers obtained by enzymatic hydrolysis of the glucomannan produced by the plant Amorphophallus konjac. Carbohydrate Research, 2002, 337: 2505-251110.1016/S0008-6215(02)00332-4Suche in Google Scholar
[4] Xu G, Wang C, Shen M, et al., Shoot tips culture and plant regeneration in Amorphophallus konjac in vitro, Biotechnology., 1993, 4, 19-21Suche in Google Scholar
[5] Zhang XG., Tissue culture of elephant-foot yam (in Chinese), Southwest Agric. Univ., 1998, 10, 345-349Suche in Google Scholar
[6] Wang PH, Xie Q, Zhang Y, Gao L, et al., Study on differention conditions of tissue culture of different explants from Amorphophallus albus, Journal of Yunnan Normal University (Natural Sciences Edition)., 2000, 21, 66-69Suche in Google Scholar
[7] Hu J B, Liu J, Yan H B, et al., Histological observations of morphogenesis in petiole derived callus of Amorphophallus rivieri Durieu in vitro, Plant Cell Reports., 2005, 24, 642-8.10.1007/s00299-005-0002-8Suche in Google Scholar PubMed
[8] Zhao L, Wu J, Diao Y, et al., Embryogenesis and plant regeneration from unpollinated ovaries of Amorphophallus konjac, African Journal of Biotechnology., 2012, 11, 13472-13476.10.5897/AJB12.1827Suche in Google Scholar
[9] Vibha J B, Choudhary K, Singh M, et al., An efficient somatic embryogenesis system for velvet bean [Mucuna pruriens (L.) DC.]: a source of anti-Parkinson’s drug, Plant Cell, Tissue and Organ., 2009, 99,319-32510.1007/s11240-009-9607-xSuche in Google Scholar
[10] Zimmerman J L, Somatic embryogenesis: a model for early development in higher plants, The Plant Cell, 1993, 5, 141110.2307/3869792Suche in Google Scholar
[11] Von Arnold S, Sabala I, Bozhkov P, et al., Developmental pathways of somatic embryogenesis, Plant Cell, Tissue and Organ Culture., 2002, 69, 233-24910.1023/A:1015673200621Suche in Google Scholar
[12] Mikuła A, Rybczyński J J., Somatic embryogenesis of Gentiana genus I. The effect of the preculture treatment and primary explant origin on somatic embryogenesis of Gentiana cruciata (L), G. pannonica (Scop.), and G. tibetica (King), Acta Physiologiae Plantarum., 2001, 23, 15-2510.1007/s11738-001-0017-xSuche in Google Scholar
[13] Rayburn A L, Crawford J, Rayburn C M, et al., Genome size of three Miscanthus species, Plant Molecular Biology Reporter., 2009, 27, 184-18810.1007/s11105-008-0070-3Suche in Google Scholar
[14] Arumuganathan K, Earle E D., Estimation of nuclear DNA content of plants by flow cytometry, Plant Molecular Biology Reporter., 1991, 9: 229-24110.1007/BF02672073Suche in Google Scholar
[15] Pavlović S, Vinterhalter B, Zdravković-Korać S, Vinterhalter D, Zdravković J, Ćosić T et al., In vitro plant regeneration from immature zygotic embryos and repetitive somatic embryogenesis in kohlrabi (Brassica oleracea var. gongylodes), In Vitro Cellular & Developmental Biology-Plant., 2013, 49, 294-30310.1007/s11627-013-9517-9Suche in Google Scholar
[16] Raghavan V, Role of 2, 4-dichlorophenoxyacetic acid (2, 4-D) in somatic embryogenesis on cultured zygotic embryos of Arabidopsis: cell expansion, cell cycling, and morphogenesis during continuous exposure of embryos to 2, 4-D, American Journal of Botany., 2004, 91, 1743-175610.3732/ajb.91.11.1743Suche in Google Scholar PubMed
[17] Chen A H, Yang J L, Da Niu Y, et al., High-frequency somatic embryogenesis from germinated zygotic embryos of Schisandra chinensis and evaluation of the effects of medium strength, sucrose, GA3, and BA on somatic embryo development, Plant Cell, Tissue and Organ Culture (PCTOC)., 2010, 102: 357-36410.1007/s11240-010-9740-6Suche in Google Scholar
[18] Kim S W, Oh S C, Liu J R., Control of direct and indirect somatic embryogenesis by exogenous growth regulators in immature zygotic embryo cultures of rose, Plant cell, tissue and organ culture., 2003, 74, 61-66.10.1023/A:1023355729046Suche in Google Scholar
[19] Féher A, Pasternak T P, Dudits D. Transition of somatic plant cells to an embryogenic state, Plant Cell, Tissue and Organ Culture., 2003, 74, 201-228.10.1023/A:1024033216561Suche in Google Scholar
[20] Raemakers C, Jacobsen E, Visser R G F., Secondary somatic embryogenesis and applications in plant breeding, Euphytica., 1995, 81, 93-10710.1007/BF00022463Suche in Google Scholar
[21] Vasic D, Alibert G, Skoric D., Protocols for efficient repetitive and secondary somatic embryogenesis in Helianthus maximiliani (Schrader), Plant Cell Reports., 2001, 20, 121-12510.1007/s002990000291Suche in Google Scholar PubMed
[22] Pinto G, Valentim H, Costa A, et al., Somatic embryogenesis in leaf callus from a mature Quercus suber L. tree, In Vitro Cellular & Developmental Biology-Plant., 2002, 38, 569-57210.1079/IVP2002352Suche in Google Scholar
[23] Bueno M A, Gomez A, Vicente O, et al., Stability in ploidy level during somatic embryogenesis in Quercus canariensis., Somatic Cell Genetics and Molecular Genetics of Trees, Springer Netherlands, 1996: 23-2810.1007/978-94-011-3983-0_4Suche in Google Scholar
[24] Kubaláková M, Doležel J, Lebeda A. Ploidy instability of embryogenic cucumber (Cucumis sativus L.) callus culture. Biologia Plantarum., 1996, 38(3): 475.10.1007/BF02896685Suche in Google Scholar
[25] Tremblay L, Levasseur C, Tremblay F M., Frequency of somaclonal variation in plants of black spruce (Picea mariana, Pinaceae) and white spruce (P. glauca, Pinaceae) derived from somatic embryogenesis and identification of some factors involved in genetic instability, American journal of botany., 1999, 86, 1373-138110.2307/2656920Suche in Google Scholar
[26] Kudo N, Kimura Y., Patterns of endopolyploidy during seedling development in cabbage (Brassica oleracea L.), Annals of Botany., 2001, 87, 275-281.10.1006/anbo.2000.1337Suche in Google Scholar PubMed
[27] Endemann M, Hristoforoglu K, Stauber T, et al., Assessment of age-related polyploidy in Quercus robur L. somatic embryos and regenerated plants using DNA flow cytometry, Biologia Plantarum., 2001, 44, 339-345.10.1023/A:1012426306493Suche in Google Scholar
[28] López-Pérez A J, Carreño J, Martinez-Cutillas A, et al., High embryogenic ability and plant regeneration of table grapevine cultivars (Vitis vinifera L.) induced by activated charcoal, VITIS-Journal of Grapevine Research., 2015, 44, 79.Suche in Google Scholar
[29] Pavlović S, Vinterhalter B, Zdravković-Korać S, et al., Recurrent somatic embryogenesis and plant regeneration from immature zygotic embryos of cabbage (Brassica oleracea var. capitata) and cauliflower (Brassica oleracea var. botrytis). Plant Cell, Tissue and Organ Culture (PCTOC)., 2013, 113, 397-40610.1007/s11240-012-0279-6Suche in Google Scholar
© 2017 L. Zhong et al.
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
Artikel in diesem Heft
- Research Articles
 - Field Performance and Genetic Fidelity of Micropropagated Plants of Coffea canephora (Pierre ex A. Froehner)
 - Research Articles
 - Foliage maturity of Quercus ilex affects the larval development of a Croatian coastal population of Lymantria dispar (Lepidoptera: Erebidae)
 - Research Articles
 - Structural and functional impact of SNPs in P-selectin gene: A comprehensive in silico analysis
 - Research Articles
 - High embryogenic ability and regeneration from floral axis of Amorphophallus konjac (Araceae)
 - Research Articles
 - Terpene content of wine from the aromatic grape variety ‘Irsai Oliver’ (Vitis vinifera L.) depends on maceration time
 - Research Articles
 - Light and smell stimulus protocol reduced negative frontal EEG asymmetry and improved mood
 - Research Articles
 - Swailing affects seed germination of plants of European bio-and agricenosis in a different way
 - Research Articles
 - Survey analysis of soil physicochemical factors that influence the distribution of Cordyceps in the Xiahe Region of Gansu Province
 - Research Articles
 - Production of biogas: relationship between methanogenic and sulfate-reducing microorganisms
 - Research Articles
 - Pentraxin 3 and atherosclerosis among type 2 diabetic patients
 - Research Articles
 - Evaluation of ribosomal P0 peptide as a vaccine candidate against Argulus siamensis in Labeo rohita
 - Research Articles
 - Variation of autosomes and X chromosome STR in breast cancer and gynecological cancer tissues
 - Research Articles
 - Response of antioxidant enzymes to cadmium-induced cytotoxicity in rat cerebellar granule neurons
 - Research Articles
 - Cardiac hypertrophy and IGF-1 response to testosterone propionate treatment in trained male rats
 - Research Articles
 - BRAF-activated non-protein coding RNA (BANCR) advances the development of esophageal squamous cell carcinoma via cell cycle
 - Research Articles
 - The influence of soil salinity on volatile organic compounds emission and photosynthetic parameters of Solanum lycopersicum L. varieties
 - Research Articles
 - Simple Protocol for immunoglobulin G Purification from Camel “Camelus dromedarius” Serum
 - Research Articles
 - Expression of psbA1 gene in Synechocystis sp. PCC 6803 is influenced by CO2
 - Research Articles
 - Frequency of Thrombophilic Gene Mutations in Patients with Deep Vein Thrombosis and in Women with Recurrent Pregnancy Loss
 - Research Articles
 - Evaluation of anticancer properties of a new α-methylene-δ-lactone DL-249 on two cancer cell lines
 - Research Articles
 - Impact of heated waters on water quality and macroinvertebrate community in the Narew River (Poland)
 - Research Articles
 - Effects of Some Additives on In Vitro True Digestibility of Wheat and Soybean Straw Pellets
 - Research Articles
 - RNAi-mediated gene silencing in Rhynchophorus ferrugineus (Oliver) (Coleoptera: Curculionidae)
 - Research Articles
 - New pathway of icariin-induced MSC osteogenesis: transcriptional activation of TAZ/Runx2 by PI3K/Akt
 - Research Articles
 - Tudor-SN protein expression in colorectal cancer and its association with clinical characteristics
 - Research Articles
 - Proteomic and bioinformatics analysis of human saliva for the dental-risk assessment
 - Research Articles
 - Reverse transcriptase sequences from mulberry LTR retrotransposons: characterization analysis
 - Research Articles
 - Strain Stimulations with Different Intensities on Fibroblast Viability and Protein Expression
 - Research Articles
 - miR-539 mediates osteoblast mineralization by regulating Distal-less genes 2 in MC3T3-E1 cell line
 - Research Articles
 - Diversity of Intestinal Microbiota in Coilia ectenes from Lake Taihu, China
 - Research Articles
 - The production of arabitol by a novel plant yeast isolate Candida parapsilosis 27RL-4
 - Research Articles
 - Effectiveness of Azospirillum brasilense Sp245 on young plants of Vitis vinifera L.
 - Research Articles
 - Changes of photochemical efficiency and epidermal polyphenols content of Prosopis glandulosa and Prosopis juliflora leaves exposed to cadmium and copper
 - Research Articles
 - Ultraweak photon emission in strawberry fruit during ripening and aging is related to energy level
 - Research Articles
 - Molecular cloning, characterization and evolutionary analysis of leptin gene in Chinese giant salamander, Andrias davidianus
 - Research Articles
 - Longevity and stress resistance are affected by activation of TOR/Myc in progenitor cells of Drosophila gut
 - Research Articles
 - Curcumin attenuates oxidative stress in liver in Type 1 diabetic rats
 - Research Articles
 - Risk factors of long-term postoperative renal function after partial nephrectomy in a solitary kidney
 - Research Articles
 - Developmental anomalies of the right hepatic lobe: systematic comparative analysis of radiological features
 - Review articles
 - Genetic Defects Underlie the Non-syndromic Autosomal Recessive Intellectual Disability (NS-ARID)
 - Review articles
 - Research Progress on Tissue Culture and Genetic Transformation of Kenaf (Hibiscus cannabinus)
 - Topical Issue On Precision Medicine
 - MiR-107 inhibits proliferation of lung cancer cells through regulating TP53 regulated inhibitor of apoptosis 1 (TRIAP1)
 - Topical Issue On Precision Medicine
 - The functional role of exosome microRNAs in lung cancer
 - Topical Issue On Precision Medicine
 - The diagnostic value of serum microRNA-183 and TK1 as biomarkers for colorectal cancer diagnosis
 - Topical Issue On Precision Medicine
 - Screening feature modules and pathways in glioma using EgoNet
 - Topical Issue On Precision Medicine
 - Isoliquiritigenin inhibits colorectal cancer cells HCT-116 growth by suppressing the PI3K/AKT pathway
 - Topical Issue On Precision Medicine
 - Association between Caveolin-1 expression and pathophysiological progression of femoral nerves in diabetic foot amputation patients
 - Topical Issue On Precision Medicine
 - Biomarkers in patients with myocardial fibrosis
 - Topical Issue On Precision Medicine
 - Dysregulated pathways for off-pump coronary artery bypass grafting
 - Topical Issue On Precision Medicine
 - Individualized identification of disturbed pathways in sickle cell disease
 - Topical Issue On Precision Medicine
 - The prognostic value of serum PCT, hs-CRP, and IL-6 in patients with sepsis
 - Topical Issue On Precision Medicine
 - Sevoflurane-medicated the pathway of chemokine receptors bind chemokines in patients undergoing CABG
 - Topical Issue On Precision Medicine
 - The functional role of microRNAs in laryngeal carcinoma
 - Topical Issue On Precision Medicine
 - Revealing pathway cross-talk related to diabetes mellitus by Monte Carlo Cross-Validation analysis
 - Topical Issue On Precision Medicine
 - Correlation between CDKAL1 rs10946398C>A single nucleotide polymorphism and type 2 diabetes mellitus susceptibility: A meta-analysis
 - Special Issue on Agricultural and Biological Sciences
 - Effects of environmental variables on seedling distribution of rare and endangered Dacrydium pierrei
 - Special Issue on Agricultural and Biological Sciences
 - Study on synthesis and properties of nanoparticles loaded with amaryllidaceous alkaloids
 - Special Issue on Agricultural and Biological Sciences
 - Bacterial Infection Potato Tuber Soft Rot Disease Detection Based on Electronic Nose
 - Special Issue on Agricultural and Biological Sciences
 - Effects of subsoiling on maize yield and water-use efficiency in a semiarid area
 
Artikel in diesem Heft
- Research Articles
 - Field Performance and Genetic Fidelity of Micropropagated Plants of Coffea canephora (Pierre ex A. Froehner)
 - Research Articles
 - Foliage maturity of Quercus ilex affects the larval development of a Croatian coastal population of Lymantria dispar (Lepidoptera: Erebidae)
 - Research Articles
 - Structural and functional impact of SNPs in P-selectin gene: A comprehensive in silico analysis
 - Research Articles
 - High embryogenic ability and regeneration from floral axis of Amorphophallus konjac (Araceae)
 - Research Articles
 - Terpene content of wine from the aromatic grape variety ‘Irsai Oliver’ (Vitis vinifera L.) depends on maceration time
 - Research Articles
 - Light and smell stimulus protocol reduced negative frontal EEG asymmetry and improved mood
 - Research Articles
 - Swailing affects seed germination of plants of European bio-and agricenosis in a different way
 - Research Articles
 - Survey analysis of soil physicochemical factors that influence the distribution of Cordyceps in the Xiahe Region of Gansu Province
 - Research Articles
 - Production of biogas: relationship between methanogenic and sulfate-reducing microorganisms
 - Research Articles
 - Pentraxin 3 and atherosclerosis among type 2 diabetic patients
 - Research Articles
 - Evaluation of ribosomal P0 peptide as a vaccine candidate against Argulus siamensis in Labeo rohita
 - Research Articles
 - Variation of autosomes and X chromosome STR in breast cancer and gynecological cancer tissues
 - Research Articles
 - Response of antioxidant enzymes to cadmium-induced cytotoxicity in rat cerebellar granule neurons
 - Research Articles
 - Cardiac hypertrophy and IGF-1 response to testosterone propionate treatment in trained male rats
 - Research Articles
 - BRAF-activated non-protein coding RNA (BANCR) advances the development of esophageal squamous cell carcinoma via cell cycle
 - Research Articles
 - The influence of soil salinity on volatile organic compounds emission and photosynthetic parameters of Solanum lycopersicum L. varieties
 - Research Articles
 - Simple Protocol for immunoglobulin G Purification from Camel “Camelus dromedarius” Serum
 - Research Articles
 - Expression of psbA1 gene in Synechocystis sp. PCC 6803 is influenced by CO2
 - Research Articles
 - Frequency of Thrombophilic Gene Mutations in Patients with Deep Vein Thrombosis and in Women with Recurrent Pregnancy Loss
 - Research Articles
 - Evaluation of anticancer properties of a new α-methylene-δ-lactone DL-249 on two cancer cell lines
 - Research Articles
 - Impact of heated waters on water quality and macroinvertebrate community in the Narew River (Poland)
 - Research Articles
 - Effects of Some Additives on In Vitro True Digestibility of Wheat and Soybean Straw Pellets
 - Research Articles
 - RNAi-mediated gene silencing in Rhynchophorus ferrugineus (Oliver) (Coleoptera: Curculionidae)
 - Research Articles
 - New pathway of icariin-induced MSC osteogenesis: transcriptional activation of TAZ/Runx2 by PI3K/Akt
 - Research Articles
 - Tudor-SN protein expression in colorectal cancer and its association with clinical characteristics
 - Research Articles
 - Proteomic and bioinformatics analysis of human saliva for the dental-risk assessment
 - Research Articles
 - Reverse transcriptase sequences from mulberry LTR retrotransposons: characterization analysis
 - Research Articles
 - Strain Stimulations with Different Intensities on Fibroblast Viability and Protein Expression
 - Research Articles
 - miR-539 mediates osteoblast mineralization by regulating Distal-less genes 2 in MC3T3-E1 cell line
 - Research Articles
 - Diversity of Intestinal Microbiota in Coilia ectenes from Lake Taihu, China
 - Research Articles
 - The production of arabitol by a novel plant yeast isolate Candida parapsilosis 27RL-4
 - Research Articles
 - Effectiveness of Azospirillum brasilense Sp245 on young plants of Vitis vinifera L.
 - Research Articles
 - Changes of photochemical efficiency and epidermal polyphenols content of Prosopis glandulosa and Prosopis juliflora leaves exposed to cadmium and copper
 - Research Articles
 - Ultraweak photon emission in strawberry fruit during ripening and aging is related to energy level
 - Research Articles
 - Molecular cloning, characterization and evolutionary analysis of leptin gene in Chinese giant salamander, Andrias davidianus
 - Research Articles
 - Longevity and stress resistance are affected by activation of TOR/Myc in progenitor cells of Drosophila gut
 - Research Articles
 - Curcumin attenuates oxidative stress in liver in Type 1 diabetic rats
 - Research Articles
 - Risk factors of long-term postoperative renal function after partial nephrectomy in a solitary kidney
 - Research Articles
 - Developmental anomalies of the right hepatic lobe: systematic comparative analysis of radiological features
 - Review articles
 - Genetic Defects Underlie the Non-syndromic Autosomal Recessive Intellectual Disability (NS-ARID)
 - Review articles
 - Research Progress on Tissue Culture and Genetic Transformation of Kenaf (Hibiscus cannabinus)
 - Topical Issue On Precision Medicine
 - MiR-107 inhibits proliferation of lung cancer cells through regulating TP53 regulated inhibitor of apoptosis 1 (TRIAP1)
 - Topical Issue On Precision Medicine
 - The functional role of exosome microRNAs in lung cancer
 - Topical Issue On Precision Medicine
 - The diagnostic value of serum microRNA-183 and TK1 as biomarkers for colorectal cancer diagnosis
 - Topical Issue On Precision Medicine
 - Screening feature modules and pathways in glioma using EgoNet
 - Topical Issue On Precision Medicine
 - Isoliquiritigenin inhibits colorectal cancer cells HCT-116 growth by suppressing the PI3K/AKT pathway
 - Topical Issue On Precision Medicine
 - Association between Caveolin-1 expression and pathophysiological progression of femoral nerves in diabetic foot amputation patients
 - Topical Issue On Precision Medicine
 - Biomarkers in patients with myocardial fibrosis
 - Topical Issue On Precision Medicine
 - Dysregulated pathways for off-pump coronary artery bypass grafting
 - Topical Issue On Precision Medicine
 - Individualized identification of disturbed pathways in sickle cell disease
 - Topical Issue On Precision Medicine
 - The prognostic value of serum PCT, hs-CRP, and IL-6 in patients with sepsis
 - Topical Issue On Precision Medicine
 - Sevoflurane-medicated the pathway of chemokine receptors bind chemokines in patients undergoing CABG
 - Topical Issue On Precision Medicine
 - The functional role of microRNAs in laryngeal carcinoma
 - Topical Issue On Precision Medicine
 - Revealing pathway cross-talk related to diabetes mellitus by Monte Carlo Cross-Validation analysis
 - Topical Issue On Precision Medicine
 - Correlation between CDKAL1 rs10946398C>A single nucleotide polymorphism and type 2 diabetes mellitus susceptibility: A meta-analysis
 - Special Issue on Agricultural and Biological Sciences
 - Effects of environmental variables on seedling distribution of rare and endangered Dacrydium pierrei
 - Special Issue on Agricultural and Biological Sciences
 - Study on synthesis and properties of nanoparticles loaded with amaryllidaceous alkaloids
 - Special Issue on Agricultural and Biological Sciences
 - Bacterial Infection Potato Tuber Soft Rot Disease Detection Based on Electronic Nose
 - Special Issue on Agricultural and Biological Sciences
 - Effects of subsoiling on maize yield and water-use efficiency in a semiarid area