The role of γ -aminobutyric acid (Gaba) in somatic embryogenesis of Acca sellowiana Berg. (Myrtaceae) (original) (raw)
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The role of γ-aminobutyric acid (Gaba) in somatic embryogenesis of Acca sellowiana Berg.(Myrtaceae)
Brazilian Journal of …, 2009
The γ-aminobutyric acid (Gaba) is a non-protein amino acid found in prokaryotes and eukaryotes. Its role in plant development has not been fully established. This study reports a quantification of the levels of endogenous Gaba, as well as investigation of its role in different stages of somatic embryogenesis in Acca sellowiana Berg. (Myrtaceae). Zygotic embryos were used as explants and they were inoculated into the culture medium contained different concentrations of Gaba (0,2, 4, 6, 8 and 10 μM). The highest concentrations of endogenous Gaba were detected between the third and nine days after inoculation, reaching the value of 12.77 μmol.g -1 FW. High frequency of somatic embryogenesis was observed in response to 10 μM Gaba. This treatment also resulted in a large number of normal embryos, and the lowest percentage of formation of fused somatic embryos, phenotypic characteristic of most deformed embryos in all treatments. Also, all treatments promoted the formation of the somatic embryos with positive characteristics of development resumption, which however did not originate the seedlings.
Somatic embryogenesis (SE) is an analogous process to zygotic embryogenesis (ZE); both complex processes are influenced by a significant number of genetic and environmental factors. Amino acids are considered important regulators of morphogenesis in several plant species, therefore the aim of this study was to determine the role of amino acids in embryo ontogeny in Acca sellowiana. Endogenous levels of amino acids were quantified at different stages of development during both direct and indirect somatic embryogenesis (DSE and ISE) and during ZE. During ZE, there was an increase in total amino acids between 18 and 27 days after pollination. During ISE and DSE, the highest contents were detected from 3 to 15 days after inoculation, coinciding with the induction of somatic embryos. In ZE, glutamine and asparagine appeared to be fundamental to the process of induction of zygotic embryos. On the other hand, the induction of somatic embryos that appeared require glutamine, gamma-aminobutyric acid (GABA) and glutamic acid. The results suggest the involvement of amino acids in the ontogenesis of zygotic and somatic embryogenesis directly and indirectly in A. sellowiana, indicating requirements for specific amino acids for each event of development.
Plant Growth Regulation, 2009
Acca sellowiana (Berg.) Burr. is a native Myrtaceae from southern Brazil and Uruguay, now the subject of a domestication and breeding program. Biotechnological tools have been used to assist in this program. The establishment of a reliable protocol of somatic embryogenesis has been pursued, with a view to capturing and fixing genetic gains. The rationale behind this work relies on the fact that deepening comprehension of the general metabolism of zygotic embryogenesis may certainly improve the protocol for somatic embryogenesis. Thus, in the present work we studied the accumulation of protein, total sugars, starch, amino acids, polyamines (PAs), IAA and ABA, in different stages of A. sellowiana zygotic embryogenesis. Starch is the predominant storage compound during zygotic embryo development. Increased synthesis of amino acids in the cotyledonary stage, mainly of asparagine, was observed throughout development. Total free PAs showed increased synthesis, whereas total conjugated PAs were mainly observed in the early developmental stages. IAA decreased and ABA increased with the progression from early to late embryogenesis. Besides providing basic information on the morphophysiological and biochemical changes of zygotic embryogenesis, the results here obtained may provide adequate strategies towards the modulation of somatic embryogenesis in this species as well as in other woody angiosperms.
American Journal of Plant Sciences, 2020
In the present study, we tested the effect of amino acids on secondary somatic embryogenesis of Moroccan cork oak (Quercus suber L.). Secondary mature and immature somatic embryos were obtained from primary somatic embryos cultured in N 30 K medium supplemented with nineteen amino acids. Stimulation of embryogenesis was dependent on the type and concentration of amino acid in the medium. Thus, L-glutamine and L-asparagine at 3.42 mM have been proved to be the most favorable for the formation of functional somatic embryos and the induction of secondary somatic embryos.
Egyptian International Journal of Palms
Somatic embryogenesis is a means by which plants can regenerate bipolar structures from somatic cells. Furthermore, a high frequency and synchronous embryogenic system is necessary to obtain the complete advantages of somatic embryogenesis. Additionally, examining the regenerability of embryogenic callus (EC) and its ability to develop further into advanced stages of somatic embryos (SEs) could therefore help in the mass production of date palm SEs. For that reason; the embryogenic callus (EC), non-embryogenic callus (NEC) and the other developing SEs phases [pro-embryos (PE) and fully developed SEs (FDSEs)] were undergone to determine the endogenous plant growth regulators (PGRs) as well as different amino acids levels. Indole-3-acetic acid (IAA), gibberellic acid (GA 3), zeatin (Z) and 2isopentenyladenine (2iP) concentrations reached their lowest levels in EC in comparing with the other developing SEs phases (PE and FDSEs). However, NEC had the greatest level of ABA. Furthermore, FDSEs had high levels of GA 3 and total cytokinins (CKs). In contrast to FDSEs and NEC, which had high 2iP/zeatin ratios, EC and PE had elevated IAA/CKs ratio. IAA/ABA ratio increased significantly in PE. On either hand, EC had the highest significant quantities of aspartic, alanine, histidine and lysine than PE and FDSEs. Whereas, NEC had the highest significant levels of glycine, tyrosine, and phenylalanine, but no proline was detected in NEC or PE. Serine, glutamic, and arginine levels were high in FDSEs. In PE, the level of threonine increased considerably. These determined biochemical components are highly of importance since the discovery that the induction and expression of somatic embryogenesis are totally dependent on their endogenous levels from PGRs and free amino acids.
Plant Growth Regulation, 2006
The aim of this work was to study morphological and biochemical aspects during zygotic embryogenesis in O. catharinensis, by measuring changes in the endogenous concentrations of proteins, amino acids, polyamines (PAs), indole-3-acetic acid (IAA) and abscisic acid (ABA). Buffer-soluble and insoluble protein contents were determined by spectrometry, and amino acids, PAs, IAA and ABA concentrations were determined by high performance liquid chromatography. Total amino acid accumulation, predominantly asparagine, occurred when the embryo showed completely developed cotyledons, with posterior reduction in the mature embryo. This decrease in total amino acid concentration in the mature embryo may result from their use in storage as well as for LEA protein synthesis. Free putrescine (Put) concentration decreased, while free spermine (Spm) increased during embryo development. This suggest a role for Put in the initial phases of embryogenesis when high rates of cell division occur, while elevated concentration of Spm are essential from the middle to the end of embryo development, when growth is mainly due to cell elongation. An IAA peak in zygotic embryos occurred during initial development, suggesting a link between growth and cellular division as well as with the establishment of bilateral symmetry. ABA concentration declined during initial stages of development then increased at the mature embryo stage, suggesting a possible relationship with dormancy and recalcitrance characteristics. Our results show that changes in the phytohormones (IAA, ABA and PAs) concentrations in combination with amino acids are likely important factors determining the developmental stages of O. catharinensis zygotic embryos.
Anomalous somatic embryos in Acca sellowiana (O. Berg) Burret (Myrtaceae)
Revista Brasileira de Botânica, 2008
-(Anomalous somatic embryos in Acca sellowiana (O. Berg) Burret (Myrtaceae). Somatic embryogenesis represents a valuable tool for the studies on the basic aspects of plant embryo development. Today this process is used as a potencial technique for large-scale plant micropropagation although, so far, it has been applied to only a small number of species. However, when somatic embryos are malformed they are considered economically useless. In Acca sellowiana (O. Berg) Burret, an important fruit-producing crop, large amounts of anomalous somatic embryos (76.3%) were found just after 40 days of culture of explants in a 2,4-D containing medium. Among the anomalous forms found in the cotiledonary stage, 12.2% consisted of fused embryos, 40.4% displayed fused cotyledons, 13.0% presented supernumerary cotyledons, and 10.7% showed absence or poorly developed cotyledons, including those without the shoot apical meristem. Histological analyses indicated that the altered embryos were formed either directly from cotyledons, hypocotyl and radicle of the zygotic embryos used as explants, or indirectly from calli formed from these tissue parts. It is suggested that the formation of anomalous somatic embryos, as well as a low frequency of conversion into emblings reflect physiological and/or genetic disturbances triggered by the presence of 2,4-D in the medium. In vitro experimental alternative approaches are discussed in order to lessen the occurrence of malformed somatic embryos.
Somatic embryogenesis in goiabeira serrana: genotype response, auxinic shock and synthetic seeds
Revista Brasileira De Fisiologia Vegetal, 2001
The induction and control of in vitro somatic embryogenesis is dependent of a number of factors. The genotype of the mother plant donor of explants and the kind of auxin play essential roles in conferring embryogenic competence. Once obtained somatic embryos may be encapsulated in alginate originating synthetic seeds that can be stored at low temperatures. Considering this the present work aimed at the assessment of five different genotypes, five periods of 2,4-D shock (20 µM for 1, 2, 4, 8 and 16 weeks) (), and different substances supplemented to sodium alginate to obtain synthetic seeds. Zygotic embryos of Feijoa sellowiana were inoculated in basal LP medium (von Arnold and Erikson, 1981) supplemented with Morel's vitamins, sucrose (3%) and phytagel (0.2%). The highest rates of somatic embryogenesis induction were observed in the genotypes 50-4 and 101. Shock of two weeks in 2,4-D conferred embryogenic competence in the same levels obtained with the shock of 8 weeks. Histological evaluations revealed the direct origin of the somatic embryos from the epidermic surface of cotyledons. Synthetic seeds containing MS salts and sucrose resulted in higher rates of contamination than capsules free of these substances. KNO 3 (100 mM) resulted in the opening of 81.2% of the capsules as compared to 0% of opening in the treatment with water. ADDITIONAL INDEX TERMS: Acca sellowiana, micropropagation, pineapple-guava, encapsulation. ABBREVIATIONS: CH -Casein Hydrolysate; 2,4-D -2,4-dichlorophenoxyacetic acid; GA 3 -gibberellic acid; Gln -L-glutamine; LPm -von Arnold and Eriksson (1981) modified medium; Kin -Kinetin; ½MShalf strength Murashige and Skoog's; SE -somatic embryos; somatic embryogenesis; ZE -zygotic embryos.
The aim of the present study was to estimate the endogenous abscisic acid (ABA) content in tulip 'Apel-doorn' torpedo and mature somatic embryos. Moreover, the effect of exogenous ABA and/or its inhibitor fluridone on somatic embryo maturation and conversion into plantlets was investigated. Torpedo-stage somatic embryos were subcultured on media containing 5 lM of picloram and 1 lM of 6-benzyl-aminopurine (BAP)—control, and combinations of ABA (0 or 10 lM) and/or fluridone (0 or 30 lM) for 1 week. Then, the torpedo embryos were transferred to a maturation medium containing 0.25 lM of a-naphthaleneacetic acid (NAA) and 2.5 lM of BAP, without ABA and fluridone treatment, and cultivated under darkness or light for ten weeks. Endogenous ABA content (first time measured in tulip somatic embryos) was evaluated by ELISA test. The obtained results revealed that the highest level of endogenous ABA, at 17.45 nmol g-1 dry weight (DW), was recorded in torpedo-stage of tulip embryo development, only after 1 week of ABA treatment, and was nearly 10 times higher in comparison with the control. Simultaneous addition of ABA and fluridone to the medium resulted in the lowering of the ABA concentration to 9.58 nmol g-1 DW. During ten weeks of maturation of the embryos, the endogenous ABA content in mature tissue of tulip somatic embryo considerably decreased to an amount 0.87–1.33 nmol g-1 DW (irrespective of ABA and fluridone treatment) and did not differ significantly from control (0.59 nmol g-1 DW). Exogenous ABA and fluridone significantly decreased the growth value of fresh weight (FW) of the tulip torpedo-shaped and mature embryos under light conditions. Percentage of the DW of the torpedo embryos treated with exogenous ABA was significantly higher (15.43–17.02) in comparison with the control (10.87). Three to three and a half times more malformed mature embryos were noted under light conditions than in darkness, irrespective of ABA and fluridone treatment. The highest percentage of mature embryos forming shoots (conversion) was observed under light conditions in the control and after fluridone treatment (26 and 20%, respectively).