Shoot apical development during in vitro embryogenesisThis review is one of a selection of papers published on the Special Theme of Shoot Apical Meristems.

2006 ◽  
Vol 84 (11) ◽  
pp. 1650-1659 ◽  
Author(s):  
Muhammad Tahir ◽  
Claudio Stasolla
Keyword(s):  
Shoot Apical Meristem ◽  
Somatic Embryos ◽  
Apical Meristem ◽  
Flowering Plants ◽  
Model Systems ◽  
Marker Genes ◽  
Zygotic Embryos ◽  
Stage Of Development ◽  
Meristem Development

Formation of the shoot apical meristem (SAM) has been extensively investigated in zygotic embryos of flowering plants, where it follows a prolonged and dynamic developmental pattern underlined by precise temporal and spatial changes in gene expression. Studies conducted on the plant model system Arabidopsis have revealed that SAM formation is controlled by a genetic network and involves the participation of several regulatory genes expressed at different stages of development. As a general rule apical meristem development in vivo occurs very early; at the globular stage of development in flowering plants and in club-stage embryos of conifers. Once formed, meristems of zygotic embryos are stable structures that become reactivated at the onset of germination. Shoot apical meristem formation during in vitro embryogenesis is demarked by structural events similar to those described for zygotic embryos, although differences can be observed during the late phases of development, where cellular differentiation and formation of intercellular spaces disrupt the architecture of SAMs produced in culture. These events, which denote the “unstable” nature of SAMs of somatic embryos, often result in poor conversion frequency and reduced plant regeneration. By using Picea glauca (Moench) Voss (white spruce) somatic embryos and microspore-derived embryos of Brassica napus L. (canola) as model systems, this review provides methods for improving SAM formation through manipulations of the culture medium which alter the cellular redox status. Meristem marker genes from Arabidopsis, such as WUSCHEL (which is required for the acquisition of stem fate identity), represent a valuable tool for estimating the quality of SAM produced by microspore-derived embryos of canola. In spruce, the identification of two novel meristem marker genes, HBK1 and PgAGO, will allow similar studies in conifers.

scholarly journals Pengaruh TDZ terhadap induksi embrio somatik sagu (Metroxylon sagu Rottb.) pada tiga metode kultur berbeda (Effect of TDZ on the somatic embryo induction of sago palm (Metroxylon sagu Rottb.) in three different culture methods)

2018 ◽  
Vol 86 (1) ◽  
Author(s):  
Imron Riyadi ◽  
Darda EFENDI ◽  
Bambang S PURWOKO ◽  
Djoko SANTOSO
Keyword(s):  
Somatic Embryo ◽  
Shoot Apical Meristem ◽  
Embryogenic Callus ◽  
Somatic Embryos ◽  
Apical Meristem ◽  
Culture Methods ◽  
Sago Palm ◽  
Callus Differentiation ◽  
Metroxylon Sagu

AbstractA right combination of cytokinin is able to support the process of callus differentiation to somatic embryo formation in plant somatic embryogenesis. Liquid culture application could increase the efficiency of in vitro culture process on plants. This research aimed to determine the best concentration of TDZ combined with kinetin for callus differentiation to  somatic embryo of sago palm on three culture methods. Plant material used was embryogenic callus derived from tips meristem culture from sucker of Alitir sago palm. Callus was cultured on modified MS media added with: 0.0, 0.1, 0.5 and 1.0 mg/L TDZ combined with 0.5 mg/L kinetin for 12 weeks with subcultures every 6 weeks. Three culture methods used were suspension, temporary immersion system (TIS), and solid media. There were 12 treatments with 4 replicates. The results showed that the highest number of somatic embryos was achieved on TIS culture with 1.0 mg/L TDZ and 0.5 mg/L kinetin in 6 weeks (167.3 embryos/flask) and 12 weeks (389.2 embryos/flask) with its fresh weight of 18.4 g and 29.1 g, respectively. The highset survival rate in final culture (12 weeks) was achieved on TIS culture with 1.0 mg/L TDZ and 0.5 mg/L kinetin (100%). The shortest time for somatic embryos expression was achieved on TIS culture with 1.0 mg/L TDZ and 0.5 mg/L kinetin in two weeks after culture. Histological analysis of early-stage somatic embryos showed the presence of dense and compact cellular arrangements which formed growth spot axis for shoot or SAM (shoot apical meristem) and root or RAM (root apical meristem) that connected each other. [Key words: culture method, embryogenic callus, Metroxylon sagu Rottb., kinetin, sago palm, TDZ]   AbstrakAplikasi kombinasi sitokinin yang tepat dapat mendorong proses diferensiasi kalus membentuk embrio somatik pada proses embriogenesis somatik tanaman. Penggunaan metode kultur cair dapat meningkatkan efisiensi proses kultur in vitro tanaman. Penelitian ini bertujuan untuk menentukan konsentrasi TDZ terbaik dikombinasikan dengan kinetin dalam proses diferensiasi kalus membentuk embrio somatik tanaman sagu pada tiga metode kultur. Bahan tanam penelitian  berupa kalus embriogenik tanaman sagu asal kultur meristem pucuk dari anakan sagu jenis Alitir. Kalus dikulturkan pada media modifikasi dengan penambahan  TDZ dengan konsentrasi 0,1; 0,5; dan 1,0 mg/L dikombinasikan dengan kinetin 0,5 mg/L selama 12 minggu yang disubkultur pada umur 6 minggu. Metode kultur yang digunakan terdiri atas tiga macam yaitu: kultur suspensi, sistem perendaman sesaat (SPS) dan media padat. Perlakuan terdiri atas 12 kombinasi perlakuan dengan empat ulangan. Hasil penelitian menunjukkan bahwa rerata jumlah embrio somatik tertinggi dicapai pada perlakuan metode kultur SPS dengan TDZ 1,0 mg/L baik pada umur kultur 6 minggu (167,3 buah) maupun umur 12 minggu (389,2 buah). Rerata bobot segar tertinggi juga diperoleh pada perlakuan metode kultur SPS dengan TDZ 1,0 mg/L  pada umur kultur 6 minggu (18,4 g) dan  12 minggu (29,1 g). Rerata daya hidup kultur akhir (12 minggu) tertinggi  sebesar 100% diperoleh pada perlakuan SPS. Induksi embrio somatik  tercepat yakni setelah  dua minggu diperoleh pada  metode kultur SPS dengan TDZ 1,0 mg/L dikombinasikan dengan kinetin 0,5 mg/L. Analisis histologi embrio somatik stadium awal  menunjukkan adanya susunan sel yang rapat dan kompak yang menyusun semacam poros atau berkas titik tumbuh tunas atau SAM (shoot apical meristem) maupun akar atau RAM (root apical mersitem) yang saling terhubung.[Kata kunci: kalus embriogenik, metode kultur, kinetin, TDZ, sagu, Metroxylon sagu]

scholarly journals Arabidopsis Argonaute10 Specifically Sequesters miR166/165 to Regulate Shoot Apical Meristem Development

Cell ◽  
2011 ◽  
Vol 145 (2) ◽  
pp. 242-256 ◽  
Author(s):  
Hongliang Zhu ◽  
Fuqu Hu ◽  
Ronghui Wang ◽  
Xin Zhou ◽  
Sing-Hoi Sze ◽  
...  
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Meristem Development

scholarly journals Agronomic Performance and Flowering Behavior in Response to Photoperiod and Vernalization in Barley (Hordeum vulgare L.) Genotypes with Contrasting Drought Tolerance Behavior

2021 ◽  
Author(s):  
Jamal Abu-Elenein ◽  
Rabea Al-Sayaydeh ◽  
Zahera Akkeh ◽  
Zakaria Al-Ajlouni ◽  
AbdRaheem A. Al-Bawalize ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Agronomic Performance ◽  
Short Day ◽  
Drought Tolerant ◽  
Long Day ◽  
Meristem Development ◽  
Rainfed Conditions ◽  
Barley Genotypes

Abstract Background In barley, flowering behavior is a highly regulated and complex process where the appropriate matching of reproductive development with seasonal variation in water availability confer barley adaptation to different environments. In this study, the role of variation in flowering time and drought tolerance in four selected barley genotypes was studied under field and controlled conditions. For this purpose, field trials were conducted for two consecutive seasons at three diverse environments where the studied genotypes were subjected to either rainfed conditions or rainfed plus supplementary irrigation under two different sowing dates. Furthermore, reproductive meristem development in two selected barley genotypes, Rum (drought tolerant) and Steptoe (drought-sensitive) was also assessed in response to both vernalization and water stress under two different photoperiod conditions.Results Variation in the number of days to heading was more pronounced under rainfed conditions than under well water conditions. For agronomic performance, Rum was superior under all tested environments, which assure its general adaptability to multiple environments, while Steptoe was the poorest. The transition to reproductive meristem was faster under vernalized long-day conditions as compared to vernalized short-day conditions. The progress of shoot apical meristem development and heading under long-day conditions was significantly faster in Rum than that of Steptoe. A clear effect of drought stress was observed on shoot apical meristem development in Steptoe. Under short-day conditions, vernalized Rum plants subjected to water deficit showed an advanced meristem development stage a significant earlier HD when compared with non-stressed plants. This early flowering behavior in stressed Rum plants under short-day conditions was accompanied by higher gene expression of the Vrn-H1 gene. Conclusion In conclusion, the integration of vernalization and photoperiod signals in drought-tolerant barley genotypes is associated with early flowering behavior and higher productivity in dry environments.

scholarly journals An auxin responsive CLE gene regulates shoot apical meristem development in Arabidopsis

2015 ◽  
Vol 6 ◽  
Author(s):  
Hongyan Guo ◽  
Wei Zhang ◽  
Hainan Tian ◽  
Kaijie Zheng ◽  
Xuemei Dai ◽  
...  
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Meristem Development

Histological studies of cellular differentiation during somatic embryogenesis of coconut plumule-derived calli

2015 ◽  
Vol 43 (3) ◽  
Author(s):  
K. Lakshmi Jayaraj ◽  
U. Bhavyashree ◽  
T.P. Fayas ◽  
K.K. Sajini ◽  
M.K. Rajesh ◽  
...  
Keyword(s):  
Somatic Embryogenesis ◽  
Somatic Embryos ◽  
Callus Formation ◽  
Histological Study ◽  
Shoot Meristem ◽  
Vascular Bundles ◽  
Histological Studies ◽  
Meristematic Cells ◽  
Meristem Development

<div><table cellspacing="0" cellpadding="0" align="center"><tbody><tr><td align="left" valign="top"><p>Since coconut is   one of the most recalcitrant species to generate <em>in vitro</em>, it is   necessary to study in detail about the cellular changes that occur during   somatic embryogenesis to enhance our knowledge about this phenomenon. In the   present study, coconut plumular tissues, the shoot meristem including leaf   primordia, were used as explants for <em>in vitro </em>regeneration studies.   Histological studies were carried out in different stages of plumule culture.   No noticeable growth was observed in 15 days old cultures. After 30 days,   meristematic cells could be identified. Abundance of meristematic cells,   foremost to the development of callus structures, was observed after 45 days.   After 75 days, globular friable calli were formed and histological studies   revealed the presence of meristematic centers which eventually formed somatic   embryos. The histological study of matured somatic embryos formed after 120   days of callus initiation showed a clear meristematic zone of parenchyma   cells, surrounded by vascular bundles. Histological studies, carried out for   certain abnormalities like compact calli, abnormal somatic embryoids with   rudimentary shoots and multiplied roots, revealed the presence of intact   cotyledonary leaves which seemed to inhibit the apical meristem development   of somatic embryoids. The presence of vascular bundles in the early stages of   callus formation might lead to the direct formation of meristemoids. These   results could aid future studies leading to enhanced control of the somatic   embryogenic process and greater efficiency of somatic embryo and plantlet   formation in coconut.</p></td></tr></tbody></table></div>

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