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Jie Zhao - One of the best experts on this subject based on the ideXlab platform.
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The cytological changes of tobacco zygote and Proembryo cells induced by beta-glucosyl Yariv reagent suggest the involvement of arabinogalactan proteins in cell division and cell plate formation.
BMC plant biology, 2012Co-Authors: Jie ZhaoAbstract:Background In dicotyledonous plant, the first asymmetric zygotic division and subsequent several cell divisions are crucial for Proembryo pattern formation and later embryo development. Arabinogalactan proteins (AGPs) are a family of extensively glycosylated cell surface proteins that are thought to have important roles in various aspects of plant growth and development, including embryogenesis. Previous results from our laboratory show that AGPs are concerned with tobacco egg cell fertilization and zygotic division. However, how AGPs interact with other factors involved in zygotic division and Proembryo development remains unknown.
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Comparative transcriptional analysis reveals differential gene expression between asymmetric and symmetric zygotic divisions in tobacco.
PloS one, 2011Co-Authors: Jie ZhaoAbstract:Asymmetric cell divisions occur widely during many developmental processes in plants. In most angiosperms, the first zygotic cell division is asymmetric resulting in two daughter cells of unequal size and with distinct fates. However, the critical molecular mechanisms regulating this division remain unknown. Previously we showed that treatment of tobacco zygotes with beta-glucosyl Yariv (βGlcY) could dramatically alter the first zygotic asymmetric division to produce symmetric two-celled Proembryos. In the present study, we isolated zygotes and two-celled asymmetric Proembryos in vivo by micromanipulation, and obtained symmetric, two-celled Proembryos by in vitro cell cultures. Using suppression-subtractive hybridization (SSH) and macroarray analysis differential gene expression between the zygote and the asymmetric and symmetric two-celled Proembryos was investigated. After sequencing of the differentially expressed clones, a total of 1610 EST clones representing 685 non-redundant transcripts were obtained. Gene ontology (GO) term analysis revealed that these transcripts include those involved in physiological processes such as response to stimulus, regulation of gene expression, and localization and formation of anatomical structures. A homology search against known genes from Arabidopsis indicated that some of the above transcripts are involved in asymmetric cell division and embryogenesis. Quantitative real-time PCR confirmed the up- or down-regulation of the selected candidate transcripts during zygotic division. A few of these transcripts were expressed exclusively in the zygote, or in either type of the two-celled Proembryos. Expression analyses of select genes in different tissues and organs also revealed potential roles of these transcripts in fertilization, seed maturation and organ development. The putative roles of few of the identified transcripts in the regulation of zygotic division are discussed. Further functional work on these candidate transcripts will provide important information for understanding asymmetric zygotic division, generation of apical-basal polarity and cell fate decisions during early embryogenesis.
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Localization of arabinogalactan proteins in egg cells, zygotes, and two-celled Proembryos and effects of β-D-glucosyl Yariv reagent on egg cell fertilization and zygote division in Nicotiana tabacum L.
Journal of experimental botany, 2006Co-Authors: Yuan Qin, Jie ZhaoAbstract:Arabinogalactan proteins (AGPs) have been implicated in a variety of plant development processes including sexual plant reproduction. As a crucial developmental event, plant sexual reproduction generally occurs inside an ovule embedded in an ovary. The inaccessibility of the egg cells, zygotes, and embryos has hindered our understanding of the importance of AGPs in the early events involving fertilization, zygotic division, and early embryogenesis. In this study, the well-established in vitro zygote and ovary culture systems, together with immunofluorescence and immunogold labelling techniques, were employed to investigate the role of AGPs in the early events of sexual reproduction in Nicotiana tabacum. Dramatic changes in AGP content during ovule development were evidenced by western blotting. Subcellular localization revealed that AGPs are localized in the plasma membrane, cell wall, and cytoplasm of pre- and post-fertilized egg cells, and cytoplasm and vacuoles of two-celled Proembryos. Abundant AGPs were detected in unfertilized egg cells; however, the level of AGPs substantially decreased in fertilized egg cells. Polar distribution of AGPs in elongated zygotes was observed. The early two-celled Proembryos just from zygote division displayed accumulation of AGPs at a low level, while in the elongated two-celled Proembryos at the late stage, the AGP content clearly increased. Provision of βGlcY, a synthetic phenylglycoside that specifically binds AGPs, to the in vitro cultures of isolated zygote and fertilized ovaries increased abnormal symmetrical division of zygotes. In the culture of pollinated but unfertilized ovaries, addition of βGlcY resulted in arrest of fertilization of the egg cells, but had no effect on fertilization of the central cells. The possible roles of AGPs in fertilization, zygotic division, and Proembryo development are discussed.
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In vitro development of early Proembryos and plant regeneration via microculture in Oryza sativa
Plant Cell Tissue and Organ Culture, 1998Co-Authors: Jie Zhao, Chang Zhou, Hong-yuan YangAbstract:Two convenient and efficient microculture techniques (liquid droplet and shallow-layered culture) were used to rear 2-day-old and 3 to 4 day-old Proembryos in rice. Among four cultivars, growth rate and frequency of embryogenesis were higher in the japonica cultivars than in the indica cultivars during Proembryo culture. Two-day-old Proembryos could grow and form callus only in Km8p and N6 among four kinds of tested media, and plantlets regenerated via organogenesis. Plant regeneration from callus initiated from three- and four-day-old Proembryos occurred through somatic embryogenesis and organogenesis. For in vitro embryogenesis it was essential to supplement the medium with 14 amino acids and coconut milk. The highest frequency of embryogenesis and the frequency of total induction after 14 days of culture were approximately 42% and 95% for 3-day-old Proembryos, and 45% and 100% for 4-day-old Proembryos, respectively.
Meng-xiang Sun - One of the best experts on this subject based on the ideXlab platform.
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Equal parental contribution to the transcriptome is not equal control of embryogenesis.
Nature plants, 2020Co-Authors: Peng Zhao, Xue-mei Zhou, Yifan Zheng, Yanru Ren, Meng-xiang SunAbstract:In animals, early embryogenesis is maternally controlled, whereas in plants, parents contribute equally to the Proembryo transcriptome. Thus, the question remains whether equivalent parental contribution to the transcriptome of the early Proembryo means equal control of early embryogenesis. Here, on the basis of cell-lineage-specific and allele-specific transcriptome analysis, we reveal that paternal and maternal genomes contribute equally to the transcriptomes of both the apical cell lineage and the basal cell lineage of early Proembryos. However, a strong maternal effect on basal cell lineage development was found, indicating that equal parental contribution to the transcriptome is not necessarily coupled with equivalent parental control of Proembryonic development. Parental contributions to embryogenesis therefore cannot be concluded solely on the basis of the ratio of paternal/maternal transcripts. Furthermore, we demonstrate that parent-of-origin genes display developmental-stage-dependent and cell-lineage-dependent allelic expression patterns. These findings will facilitate the investigation of specific parental roles in specific processes of early embryogenesis.
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maternal control of suspensor programmed cell death via gibberellin signaling
Nature Communications, 2019Co-Authors: Ce Shi, Hong Chen, Pan Luo, Xiaorong Huang, Tianhe Cheng, An Luo, Weicai Yang, Peng Zhao, Meng-xiang SunAbstract:Plant embryos are generated and develop in a stable and well-protected microenvironment surrounded by maternal tissue, which is vital for embryogenesis. However, the signaling mechanisms responsible for maternal tissue-to-Proembryo communication are not well understood. Here, we report a pathway for maternal tissue-to-Proembryo communication. We identify a DELLA protein, NtCRF1 (NtCYS regulative factor 1), which regulates suspensor programmed cell death (PCD). NtCRF1 can bind to the promoter of NtCYS and regulate the suspensor PCD-switch module NtCYS-NtCP14 in response to gibberellin (GA). We confirm that GA4, as a primary signal triggering suspensor PCD, is generated in the micropylar endothelium by the transient activation of NtGA3oxs in the maternal tissue. Thus, we propose that GA is a maternal-to-Proembryo communication signal that is decoded in the Proembryo by a GID1-CRF1-CYS-CP14 signaling cascade. Using this mode of communication, maternal tissue precisely controls the embryonic suspensor PCD and is able to nurse the Proembryo in a stage-dependent manner.
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Isolation of living apical and basal cell lineages of early Proembryos for transcriptome analysis.
Plant reproduction, 2018Co-Authors: Xue-mei Zhou, Ce Shi, Peng Zhao, Meng-xiang SunAbstract:Plant zygotes usually undergo asymmetrical cell division, giving rise to the formation of two daughter cells with distinct developmental cell fate. The small apical cell will develop into the major part of embryo proper, whereas the larger basal cell will divide to form a transient suspensor. Thus, the apical and basal cell lineages are an excellent model to study cell fate determination in relation to zygote polarity. However, the molecular mechanism underlying the differentiation of two distinct cell lineages is not yet understood, possibly due to the technique limitations. Previously, we have established a protocol for isolating apical cell and basal cell for cDNA library construction in tobacco. However, the method for isolating tiny Arabidopsis embryos has long been considered much more difficult. Here, we present a detailed protocol for isolating early Arabidopsis Proembryos and separating apical and basal cell lineages of Proembryos, which allow us to establish cell lineage-specific transcriptomes of early Proembryos.
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Expression pattern of NtCYS.
2013Co-Authors: Peng Zhao, Xue-mei Zhou, Li-yao Zhang, Wei Wang, Li-bo Yang, Xiong-bo Peng, Peter V. Bozhkov, Meng-xiang SunAbstract:(A) Classification of successive stages of embryogenesis in tobacco. DAP, days after pollination. Scale bars, 20 µm. (B) Semi-quantitative RT-PCR analysis of NtCYS in sperm cell (lane 1), egg cell (lane 2), zygote (lane 3), two-celled Proembryo (stage 1 of embryogenesis; lane 4), eight-celled embryo (stage 3; lane 5), 32-celled embryo (stage 4; lane 6) and heart-shaped embryo (stage 8; lane 7). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as a control. (C) RT-qPCR analysis of NtCYS in the embryos at successive developmental stages (1–9) and in both floral and vegetative tissues. The expression level of NtCYS in the Proembryos at stage 1 was set to 1. (D–I) Localization of NtCYS-GFP at the early stages of embryogenesis in proNtCYS::NtCYS-GFP plants. (D) Two-celled Proembryo (stage 1). (E) Three-celled Proembryo (between stages 1 and 2). (F) Four-celled Proembryo (stage 2). (G) Eight-celled embryo (stage 3). (H) 32-celled embryo (stage 4). (I) Early globular embryo (stage 5). Scale bars, 10 µm. Asterisks indicate the basal cell.
Huiqiao Tian - One of the best experts on this subject based on the ideXlab platform.
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isolation of zygotes and apical and basal cells of bicelluare Proembryo from torenia fournieri
Journal of Molecular Cell Biology, 2008Co-Authors: Yanhong Yang, Zu Yun Ye, Ya Ying Wang, Huiqiao TianAbstract:: Torenia fournieri is a special plant with embryo sac partly protruding through the micropyle of ovule, and the cells of egg apparatus can be clearly observed using light microscope. Zygotes and the cells of bicellular Proembryo could be isolated using enzymatic digestion. In the solution containing 0.05% cellulase and 0.05% pectinase, 14-15 zygotes were isolated from 50 ovules in 1h. In the solution containing 0.2% cellulose, 0.4% hemicellulase and 0.2% pectinase, 19 pairs of apical and basal cells of bicellular Proembryo could be isolated from 50 ovules in 1 h. The isolated zygotes and epical and basal cells were collected using a micromanipulator up to a number which will prepare for suing molecular methods to probe the mechanism of early embryogenesis of higher plants.
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Calcium distribution in the egg cell, zygote and Proembryo of lettuce (Lactuca sativa L.)
Fen zi xi bao sheng wu xue bao = Journal of molecular cell biology, 2006Co-Authors: Yi Lan Qiu, Ru Shi Liu, Dong Mei Wei, Huiqiao TianAbstract:Potassium antimonite precipitation was used to located calcium in the egg cells (before and after anthesis), zygotes and Proembryos of lettuce (Lactuca sativa L.). A few calcium precipitates (ppts) were located in the small vacuoles of cytoplasm of egg cell at 3 d before anthesis, when egg cells just formed. Then the small vacuoles fused to form some bigger vacuoles in egg cell at 2d before anthesis. Calcium ppts increased evidently in the cytoplasm and nucleus of egg cells at this time. At 1d before anthesis, a biggest vacuole located at the micropyle end of the cell and its nucleus was pushed toward the chalazal end of the cell, which made an evident cellular polarity. The number of calcium ppts in the egg cell markedly decreased, suggesting that change of calcium distribution may be related to the development of egg cell. After anthesis and before fertilization, calcium ppts were still few in the egg cells, and most of them were accumulated in the nucleus, especially in the vacuoles of nucleolus. At 4h after anthesis, egg cell was fertilized and the wall at the chalazal end of egg cell was formed completely. Calcium ppts evidently increased again in egg cell, and some big ppts appeared in the karyoplasm of nucleus and abundant small ppts in the large vacuole. At 9h after anthesis, zygote completed its first division. Calcium ppts in the nucleus and cytoplasm of two-celled Proembryo began to decrease, and only some ones accumulated in the vacuoles of nucleolus. At 18h after anthesis, zygote divided several times and became a multi-celled Proembryo. Calcium ppts in the cells of Proembryo ulteriorly diminished but there were many ppts on the surface of Proembryo. The result indicates that calcium in egg cell, zygote and the cells of Proembryo orderly changes its temporal and spatial position, which suggests that calcium may play a role during the development of egg cell and zygote.
Hong-yuan Yang - One of the best experts on this subject based on the ideXlab platform.
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Isolation of a gene preferentially expressed in heart-shaped embryos of tobacco (Nicotiana tabacum)
Sexual Plant Reproduction, 2001Co-Authors: Hong-yuan YangAbstract:We constructed two tobacco cDNA libraries from 200 microdissected undifferentiated globular Proembryos and 150 just-differentiating heart-shaped embryos using the RT-PCR technique. Through differential screening of the two cDNA libraries, a cDNA clone, designated THE3 (tobacco heart-shaped embryo 3), was sequenced and analyzed. The deduced amino acid sequence encodes a basic protein (pI 10.88) of 40.6 kDa and contains a putative nuclear targeting signal sequence. Through the whole-mount in situ hybridization, the transcript corresponding to THE3 gene shows preferential expression in heart-shaped embryos but is weakly expressed in globular Proembryos. The spatial and temporal expression of the THE3 gene suggests that it may play a role during Proembryo differentiation.
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Transformation of plant young Proembryos by electroporation
Chinese Science Bulletin, 2000Co-Authors: Shenghua Wang, Hong-yuan YangAbstract:It is first reported that plant young Proembryos expressed exogenous reporter genes by electroporation. Young Proembryos with 8–32 cells and globular Proembryos with 250–400 cells could be isolated by enzymatic maceration combined with microdissection. After electroporation withGUS orGFP genes, the Proembryos were cultured for 1–2 d in KM8p medium. At the field strength of electroporation 500–1500 V/cm, blue reaction of GUS or green fluorescence of GFP could be observed in the Proembryos. The highest transient expression frequency of young Proembryos (2.2%) was obtained at the field strength of 750 V/cm, whereas the highest frequency of globular Proembryos (5.9%) was obtained at the field strength of 1 250 V/cm. Taking the proportion of transformed cells in the whole cells of Proembryos as efficient transformation frequency, the efficient transformation frequency of the young Proembryos was 7 times that of the globular Proembryos.
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In vitro development of early Proembryos and plant regeneration via microculture in Oryza sativa
Plant Cell Tissue and Organ Culture, 1998Co-Authors: Jie Zhao, Chang Zhou, Hong-yuan YangAbstract:Two convenient and efficient microculture techniques (liquid droplet and shallow-layered culture) were used to rear 2-day-old and 3 to 4 day-old Proembryos in rice. Among four cultivars, growth rate and frequency of embryogenesis were higher in the japonica cultivars than in the indica cultivars during Proembryo culture. Two-day-old Proembryos could grow and form callus only in Km8p and N6 among four kinds of tested media, and plantlets regenerated via organogenesis. Plant regeneration from callus initiated from three- and four-day-old Proembryos occurred through somatic embryogenesis and organogenesis. For in vitro embryogenesis it was essential to supplement the medium with 14 amino acids and coconut milk. The highest frequency of embryogenesis and the frequency of total induction after 14 days of culture were approximately 42% and 95% for 3-day-old Proembryos, and 45% and 100% for 4-day-old Proembryos, respectively.
Abdelwahed Ghorbel - One of the best experts on this subject based on the ideXlab platform.
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Micromorphology, structural and ultrastructural changes during somatic embryogenesis of a Tunisian oat variety (Avena sativa L. var ‘Meliane’)
Plant Cell Tissue and Organ Culture (PCTOC), 2018Co-Authors: Manel Borji, Badra Bouamama-gzara, Farhat Chibani, Caroline Teyssier, Awatef Ben Ammar, Ahmed Mliki, Sami Zekri, Abdelwahed GhorbelAbstract:To better understand micromorphological and structural changes, histological sections provide additional insight into cellular process and developmental pathways occurring in oat somatic embryogenesis. Environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM) were also used to follow the ultrastructural modifications during this system. Histological observations allowed following the events leading to the development of mature somatic embryos. The scheme includes the following steps: cell reactivation, the first organized cell division in diads, triads, tetrads as well as octant stages, the observation of an extracellular matrix (ECM) as a fibrillar material that bounded the surface of individualized Proembryos. The transition from Proembryo stage to an early globular somatic embryo was noted, where the embryogenic cortex is surrounded by the protoderm. The late globular stage was marked by bipolarity. The early and late transitional stages, the coleoptilar, mature and germinated stages were also described. The ESEM allowed us to follow some rearrangements, related to the morphology and surfaces involved in somatic embryos development. These events are Proembryo formation, transition from Proembryo to globular stage, marked by protoderm formation, scutellum and coleoptile development and finally somatic embryos germination. The TEM showed that embryogenic cells were very rich in organelles; mitochondria, rough endoplasmic reticulum, Golgi apparatus and ribosomes. Cells of Proembryos, globular and late somatic embryos showed more vacuoles and differentiated organelles. The ECM was also detected by TEM as fibrillar material coating the cell walls. These results on structural and ultrastructural changes provided new insights and findings on oat somatic embryogenesis.
