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1.
Bot Stud ; 60(1): 6, 2019 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-31011847

RESUMO

BACKGROUND: Anoectochilus roxburghii is known for its medicinal properties, culinary interests, and ornamental applications in Asian countries. Recent studies focus mainly on its phytochemical properties and little is known about its reproductive biology, especially seed and embryo development. This study documents the major developmental events in seed and embryo development of A. roxburghii upon pollination. RESULTS: Morphological and histological studies revealed that upon pollination embryo and seed development is completed in 40 days. Ovular primordia are at the megaspore mother cell stage at the time of anthesis. Embryo development proceeds after a successful fertilization. A. roxburghii has a single cell suspensor. It elongates but not extended beyond the seed coat. A distinct cell gradient is present within the embryo proper with smaller cells located towards the chalazal end of the seed. Proteins and lipids are the major storage products within the embryo proper cells. At the stage of early globular embryo, the inner seed coat has degenerated and thus a carapace is absent at maturity. A limited deposition of lignin is detected in the mature seed coat. CONCLUSIONS: The seed of A. roxburghii matures rapidly. At maturity, the embryo proper has a well-differentiated apical zone with little constraints impose by the seed coat. These characters indicate adaptations to fast germination that may ensure a successful colonization in the shaded forest understory.

2.
Front Plant Sci ; 9: 1587, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30425727

RESUMO

Phalaenopsis is one of the most important potted plants in the ornamental market of the world. Previous reports implied that crassulacean acid metabolism (CAM) orchids at their young seedling stages might perform C3 or weak CAM photosynthetic pathways, but the detailed molecular evidence is still lacking. In this study, we used a key species in white Phalaenopsis breeding line, Phalaenopsis aphrodite subsp. formosana, to study the ontogenetical changes of CAM performance in Phalaenopsis. Based on the investigations of rhythms of day/night CO2 exchange, malate contents and phosphoenolpyruvate carboxylase (PEPC) activities, it is suggested that a progressive shift from C3 to CAM occurred as the protocorms differentiated the first leaf. To understand the role of phosphoenolpyruvate carboxylase kinase (PEPC kinase) in relation to its target PEPC in CAM performance in Phalaenopsis, the expression profiles of the genes encoding PEPC (PPC) and PEPC kinase (PPCK) were measured in different developmental stages. In Phalaenopsis, two PPC isogenes were constitutively expressed over a 24-h cycle similar to the housekeeping genes in all stages, whereas the significant day/night difference in PaPPCK expression corresponds to the day/night fluctuations in PEPC activity and malate level. These results suggest that the PaPPCK gene product is most likely involved in regulation of CAM performance in different developmental stages of Phalaenopsis seedlings.

3.
Front Plant Sci ; 9: 1043, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30065747

RESUMO

The phytohormone abscisic acid (ABA) is involved in regulating seed dormancy and germination. A crucial step of ABA biosynthesis in higher plants is the oxidative cleavage of cis-epoxycarotenoids by 9-cis-epoxycarotenoid dioxygenase (NCED). Seed development in orchids is unusual because the embryos are minute in size, without obvious histodifferentiation, and lack endosperm. To understand the regulation of ABA biosynthesis in orchid seeds, we isolated and characterized a full-length cDNA encoding an NCED homolog, PtNCED1, from developing seeds of an ornamental orchid, Phaius tankervilliae. Germination percentage was high at 90 days after pollination (DAP), when a globular embryo proper with a degenerating suspensor was evident. After 90 DAP, seed maturation was accompanied by a decrease in water content and a concomitant increase in ABA content and PtNCED1 mRNA level along with a marked decrease in germination percentage. Mature seeds pretreated with NaOCl solution lowered ABA content and improved seed germination. Moreover, after seed germination, developing protocorms could respond to dehydration stress. Dehydration of protocorms stimulated an increase in PtNCED1 level along with ABA content. Our results provide evidence of the involvement of PtNCED1 in regulating endogenous ABA content in developing seeds and protocorms. The accumulation of endogenous ABA content in orchid seeds may have a critical role in seed dormancy and the protocorm response to water stress after seed germination.

4.
BMC Genomics ; 19(1): 578, 2018 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-30068293

RESUMO

BACKGROUND: Satellite DNA is a rapidly diverging, largely repetitive DNA component of many eukaryotic genomes. Here we analyse the evolutionary dynamics of a satellite DNA repeat in the genomes of a group of Asian subtropical lady slipper orchids (Paphiopedilum subgenus Parvisepalum and representative species in the other subgenera/sections across the genus). A new satellite repeat in Paphiopedilum subgenus Parvisepalum, SatA, was identified and characterized using the RepeatExplorer pipeline in HiSeq Illumina reads from P. armeniacum (2n = 26). Reconstructed monomers were used to design a satellite-specific fluorescent in situ hybridization (FISH) probe. The data were also analysed within a phylogenetic framework built using the internal transcribed spacer (ITS) sequences of 45S nuclear ribosomal DNA. RESULTS: SatA comprises c. 14.5% of the P. armeniacum genome and is specific to subgenus Parvisepalum. It is composed of four primary monomers that range from 230 to 359 bp and contains multiple inverted repeat regions with hairpin-loop motifs. A new karyotype of P. vietnamense (2n = 28) is presented and shows that the chromosome number in subgenus Parvisepalum is not conserved at 2n = 26, as previously reported. The physical locations of SatA sequences were visualised on the chromosomes of all seven Paphiopedilum species of subgenus Parvisepalum (2n = 26-28), together with the 5S and 45S rDNA loci using FISH. The SatA repeats were predominantly localisedin the centromeric, peri-centromeric and sub-telocentric chromosome regions, but the exact distribution pattern was species-specific. CONCLUSIONS: We conclude that the newly discovered, highly abundant and rapidly evolving satellite sequence SatA is specific to Paphiopedilum subgenus Parvisepalum. SatA and rDNA chromosomal distributions are characteristic of species, and comparisons between species reveal that the distribution patterns generate a strong phylogenetic signal. We also conclude that the ancestral chromosome number of subgenus Parvisepalum and indeed of all Paphiopedilum could be either 2n = 26 or 28, if P. vietnamense is sister to all species in the subgenus as suggested by the ITS data.


Assuntos
DNA Satélite/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Hibridização in Situ Fluorescente/métodos , Orchidaceae/genética , Análise de Sequência de DNA/métodos , Mapeamento Cromossômico , DNA de Plantas/genética , DNA Ribossômico/genética , Evolução Molecular , Filogenia , RNA Ribossômico/genética , Especificidade da Espécie
5.
Front Plant Sci ; 9: 552, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29922306

RESUMO

Hydroxyproline-rich glycoproteins (HRGPs) are abundant cell wall components involved in mycorrhizal symbiosis, but little is known about their function in orchid mycorrhizal association. To gain further insight into the role of HRGPs in orchid symbiosis, the location and function of HRGPs were investigated during symbiotic germination of Dendrobium officinale. The presence of JIM11 epitope in developing protocorms was determined using immunodot blots and immunohistochemical staining procedures. Real-time PCR was also employed to verify the expression patterns of genes coding for extensin-like genes selected from the transcriptomic database. The importance of HRGPs in symbiotic germination was further investigated using 3,4-dehydro-L-proline (3,4-DHP), an inhibitor of HRGP biosynthesis. In symbiotic cultures, immunodot blots of JIM11 signals were moderate in mature seeds, and the signals became stronger in swollen embryos. After germination, signal intensities decreased in developing protocorms. In contrast, in asymbiotic cultures, JIM11 signals were much lower as compared with those stages in symbiotic cultures. Immunofluorescence staining enabled the visualization of JIM11 epitope in mature embryo and protocorm cells. Positive signals were initially localized in the larger cells near the basal (suspensor) end of uninfected embryos, marking the future colonization site of fungal hyphae. After 1 week of inoculation, the basal end of embryos had been colonized, and a strong signal was detected mostly at the mid- and basal regions of the enlarging protocorm. As protocorm development progressed, the signal was concentrated in the colonized cells at the basal end. In colonized cells, signals were present in the walls and intracellularly associated with hyphae and the pelotons. The precise localization of JIM11 epitope is further examined by immunogold labeling. In the colonized cells, gold particles were found mainly in the cell wall and the interfacial matrix near the fungal cell wall. Four extensin-like genes were verified to be highly up-regulated in symbiotically germinated protocorms as compared to asymbiotically germinated ones. The 3,4-DHP treatment inhibited the accumulation of HRGPs and symbiotic seed germination. In these protocorms, fungal hyphae could be found throughout the protocorms. Our results indicate that HRGPs play an important role in symbiotic germination. They can serve as markers for fungal colonization, establishing a symbiotic compartment and constraining fungal colonization inside the basal cells of protocorms.

6.
Am J Bot ; 105(4): 631-640, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29608785

RESUMO

PREMISE OF THE STUDY: The slipper orchids (Cypripedioideae) are a morphologically distinct subfamily of Orchidaceae. They also have some of the largest genomes in the orchids, which may be due to polyploidy or some other mechanism of genome evolution. We generated 10 transcriptomes and incorporated existing RNA-seq data to infer a multilocus nuclear phylogeny of the Cypripedioideae and to determine whether a whole-genome duplication event (WGD) correlated with the large genome size of this subfamily. Knowing more about timing of ancient polyploidy events can help us understand the evolution of one of the most species-rich plant families. METHODS: Transcriptome data were used to identify low-copy orthologous genes to infer a phylogeny of Orchidaceae and to identify paralogs to place any WGD events on the species tree. KEY RESULTS: Our transcriptome phylogeny confirmed relationships published in previous studies that used fewer markers but incorporated more taxa. We did not find a WGD event at the base of the slipper orchids; however, we did identify one on the Orchidaceae stem lineage. We also confirmed the presence of a previously identified WGD event deeper in the monocot phylogeny. CONCLUSIONS: Although WGD has played a role in the evolution of Orchidaceae, polyploidy does not appear to be responsible for the large genome size of slipper orchids. The conserved set of 775 largely single-copy nuclear genes identified in this study should prove useful in future studies of orchid evolution.


Assuntos
Genoma de Planta/genética , Evolução Biológica , Perfilação da Expressão Gênica , Genes de Plantas/genética , Marcadores Genéticos/genética , Orchidaceae , Filogenia , Poliploidia
7.
Bot Stud ; 58(1): 16, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28510199

RESUMO

BACKGROUND: Paphiopedilum rungsuriyanum from Northern Laos was discovered and described in 2014. It is characterized by having miniature tessellated leaves, a flower having a helmet shaped lip with a V-shaped neckline, and a semi-lunate, 3-dentate staminode with an umbo. These morphological features distinguish P. rungsuriyanum from the other known sections/subgenera of Paphiopedilum, making it difficult to group with existing infrageneric units. RESULTS: Paphiopedilum rungsuriyanum has chromosome number of 2n = 26. Fluorescence in situ hybridization study demonstrates that there are two 45S rDNA signals in the telomeric region of chromosomes, and more than 20 5S rDNA signals dispersed signals in the pericentromeric and centromeric regions. Phylogenetic analyses based on four nuclear (i.e. ITS, ACO, DEF4 and RAD51) and four plastid (i.e. atpI-atpH, matK, trnS-trnfM and ycf1) gene regions indicate that P. rungsuriyanum is nested in subgenus Paphiopedilum and is a sister to section Paphiopedilum. CONCLUSIONS: The results in combination with karyomorphological, rDNA FISH patterns, morphological and phylogenetic analyses suggest a new section Laosianum to accommodate this species in the current sectional circumscription of subgenus Paphiopedilum.

8.
Bot Stud ; 57(1): 18, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28597429

RESUMO

BACKGROUND: Gastrodia elata, a famous herbal medicine, has been received great attention on its treatments of headache, vertigo and epilepsy. Gastrodia nantoensis is a newly described species from central Taiwan with potential medicinal value. Gastrodia species are fully mycoheterotrophic orchids, and the courses of their seed development are more rapid as compared to the chlorophyllous orchids. A better understanding of their reproductive biology would provide insights into the propagation and conservation of the mycoheterotrophic orchid species. RESULTS: Based on the histological and histochemical investigations, we observed some notable features in ovule and embryo development. First, only the archesporial cell and/or megasporocyte are present within their ovaries at the time of anthesis. Second, their suspensors consist of a single cell and their mature embryos consist of a gradient of small to large cells. Nile red staining of a globular embryo reveals the presence of cuticular material in the surface wall of embryo proper and the lateral walls of suspensor cell, indicating that the basal wall of suspensor cell is the major route for nutrient supply from maternal tissues to embryo proper. Third, their seed coats are derived from a single integument, and lignin but not cuticular material is present in the outer most layer of seed coat and persists through seed maturation. CONCLUSIONS: The faster seed development of Gastrodia species is due to the speedy courses of ovule and embryo development. In the mature seeds, the presence of a differentiated apical zone in embryo proper suggests the easy-to-germinate character. This study provides basic knowledge for further molecular studies on embryo development and symbiotic germination of Gastrodia species.

9.
Plant Cell Physiol ; 56(11): 2079-99, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26423960

RESUMO

This study focused on the investigation of the effects of the PI motif and C-terminus of the Oncidium Gower Ramsey MADS box gene 8 (OMADS8), a PISTILLATA (PI) ortholog, on floral organ formation. 35S::OMADS8 completely rescued and 35S::OMADS8-PI (with the PI motif deleted) partially rescued petal/stamen formation, whereas these deficiencies were not rescued by 35S::OMADS8-C (C-terminal 29 amino acids deleted) in pi-1 mutants. OMADS8 could interact with Arabidopsis APETALA3 (AP3) and enter the nucleus. The nuclear entry efficiency was reduced for OMADS8-PI/AP3 and OMADS8-C/AP3. OMADS8 could also interact with OMADS5/OMADS9 (the Oncidium AP3 ortholog) and enter the nucleus with an efficiency only slightly affected by the deletion of the C-terminal sequence or PI motif. However, the stability of the OMADS8/OMADS5 and OMADS8/OMADS9 complexes was significantly reduced by deletion of the C-terminal sequence or PI motif. Further analysis indicated that the expression of genes downstream of AP3/PI (BNQ1/BNQ2/GNC/At4g30270) was compensated by 35S::OMADS8 and 35S::OMADS8-PI to a level similar to wild-type plants but was not affected by 35S::OMADS8-C in the pi-1 mutants. A similar FRET (fluorescence resonance energy transfer) efficiency was observed for Arabidopsis AGAMOUS (AG) and the Oncidium AG ortholog OMADS4 for OMADS8, OMADS8-PI and OMADS8-C. These results indicated that the OMADS8 PI motif and C-terminus were valuable for the interaction of OMADS8 with the AP3 orthologs to form higher order heterotetrameric complexes that regulated petal/stamen formation in both Oncidium orchids and transgenic Arabidopsis. However, the C-terminal sequence and PI motif were dispensable for the interaction of OMADS8 with the AG orthologs.


Assuntos
Flores/metabolismo , Proteínas de Domínio MADS/metabolismo , Orchidaceae/metabolismo , Proteínas de Plantas/metabolismo , Motivos de Aminoácidos , Arabidopsis/genética , Arabidopsis/metabolismo , Deleção de Genes , Regulação da Expressão Gênica de Plantas , Proteínas de Domínio MADS/química , Orchidaceae/genética , Proteínas de Plantas/química , Plantas Geneticamente Modificadas
10.
Plant Physiol ; 168(4): 1666-83, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26063506

RESUMO

In this study of Arabidopsis (Arabidopsis thaliana), we investigated the relationship between FOREVER YOUNG FLOWER (FYF) and Ethylene Response DNA-binding Factors (EDFs) and functionally analyzed a key FYF target, an Ethylene-Responsive Factor (ERF), that controls flower senescence/abscission. Ectopic expression of EDF1/2/3/4 caused promotion of flower senescence/abscission and the activation of the senescence-associated genes. The presence of a repressor domain in EDFs and the enhancement of the promotion of senescence/abscission in EDF1/2/3/4+SRDX (converting EDFs to strong repressors by fusion with the ERF-associated amphiphilic repression motif repression domain SRDX) transgenic plants suggested that EDFs act as repressors. The significant reduction of ß-glucuronidase (GUS) expression by 35S:FYF in EDF1/2/3/4:GUS plants indicates that EDF1/2/3/4 functions downstream of FYF in regulating flower senescence/abscission. In this study, we also characterized an ERF gene, FOREVER YOUNG FLOWER UP-REGULATING FACTOR1 (FUF1), which is up-regulated by FYF during flower development. Ectopic expression of FUF1 caused similar delayed flower senescence/abscission as seen in 35S:FYF plants. This phenotype was correlated with deficient abscission zone formation, ethylene insensitivity, and down-regulation of EDF1/2/3/4 and abscission-associated genes in 35S:FUF1 flowers. In contrast, significant promotion of flower senescence/abscission and up-regulation of EDF1/2/3/4 were observed in 35S:FUF1+SRDX transgenic dominant-negative plants, in which FUF1 is converted to a potent repressor by fusion to an SRDX-suppressing motif. Thus, FUF1 acts as an activator in suppressing EDF1/2/3/4 function and senescence/abscission of the flowers. Our results reveal that FYF regulates flower senescence/abscission by negatively regulating EDF1/2/3/4, which is the downstream gene in the ethylene response, by activating FUF1 in Arabidopsis.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Etilenos/farmacologia , Flores/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Flores/metabolismo , Flores/fisiologia , Glucuronidase/genética , Glucuronidase/metabolismo , Mutação , Reguladores de Crescimento de Planta/farmacologia , Plantas Geneticamente Modificadas , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/genética
11.
Ann Bot ; 116(3): 403-11, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26105185

RESUMO

BACKGROUND AND AIMS: Although abscisic acid (ABA) is commonly recognized as a primary cause of seed dormancy, there is a lack of information on the role of ABA during orchid seed development. In order to address this issue, the localization and quantification of ABA were determined in developing seeds of Cypripedium formosanum. METHODS: The endogenous ABA profile of seeds was measured by enzyme-linked immunosorbent assay (ELISA). Temporal and spatial distributions of ABA in developing seeds were visualized by immunohistochemical staining with monoclonal ABA antibodies. Fluoridone was applied to test the causal relationship between ABA content and seed germinability. KEY RESULTS: ABA content was low at the proembryo stage, then increased rapidly from 120 to 150 days after pollination (DAP), accompanied by a progressive decrease in water content and seed germination. Immunofluorescence signals indicated an increase in fluorescence over time from the proembryo stage to seed maturation. From immunogold labelling, gold particles could be seen within the cytoplasm of embryo-proper cells during the early stages of seed development. As seeds approached maturity, increased localization of gold particles was observed in the periplasmic space, the plasmalemma between embryo-proper cells, the surface wall of the embryo proper, and the inner walls of inner seed-coat cells. At maturity, gold particles were found mainly in the apoplast, such as the surface wall of the embryo proper, and the shrivelled inner and outer seed coats. Injection of fluoridone into capsules resulted in enhanced germination of mature seeds. CONCLUSIONS: The results indicate that ABA is the key inhibitor of germination in C. formosanum. The distinct accumulation pattern of ABA suggests that it is synthesized in the cytosol of embryo cells during the early stages of seed development, and then exported to the apoplastic region of the cells for subsequent regulatory processes as seeds approach maturity.


Assuntos
Ácido Abscísico/metabolismo , Orchidaceae/crescimento & desenvolvimento , Orchidaceae/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Sementes/crescimento & desenvolvimento , Sementes/metabolismo
12.
Ann Bot ; 116(3): 423-35, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26113634

RESUMO

BACKGROUND AND AIMS: Most fully mycoheterotrophic (MH) orchids investigated to date are mycorrhizal with fungi that simultaneously form ectomycorrhizas with forest trees. Only a few MH orchids are currently known to be mycorrhizal with saprotrophic, mostly wood-decomposing, fungi instead of ectomycorrhizal fungi. This study provides evidence that the importance of associations between MH orchids and saprotrophic non-Rhizoctonia fungi is currently under-estimated. METHODS: Using microscopic techniques and molecular approaches, mycorrhizal fungi were localized and identified for seven MH orchid species from four genera and two subfamilies, Vanilloideae and Epidendroideae, growing in four humid and warm sub-tropical forests in Taiwan. Carbon and nitrogen stable isotope natural abundances of MH orchids and autotrophic reference plants were used in order to elucidate the nutritional resources utilized by the orchids. KEY RESULTS: Six out of the seven MH orchid species were mycorrhizal with either wood- or litter-decaying saprotrophic fungi. Only one orchid species was associated with ectomycorrhizal fungi. Stable isotope abundance patterns showed significant distinctions between orchids mycorrhizal with the three groups of fungal hosts. CONCLUSIONS: Mycoheterotrophic orchids utilizing saprotrophic non-Rhizoctonia fungi as a carbon and nutrient source are clearly more frequent than hitherto assumed. On the basis of this kind of nutrition, orchids can thrive in deeply shaded, light-limiting forest understoreys even without support from ectomycorrhizal fungi. Sub-tropical East Asia appears to be a hotspot for orchids mycorrhizal with saprotrophic non-Rhizoctonia fungi.


Assuntos
Proteínas Fúngicas/genética , Micorrizas/fisiologia , Orchidaceae/fisiologia , Proteínas Fúngicas/metabolismo , Dados de Sequência Molecular , Micorrizas/genética , Micorrizas/crescimento & desenvolvimento , Orchidaceae/crescimento & desenvolvimento , Filogenia , Análise de Sequência de DNA , Taiwan
13.
Plant Cell Physiol ; 56(6): 1124-43, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25745030

RESUMO

The chromomethylase (CMT) protein family is unique to plants and controls non-CpG methylation. Here, we investigated the developmental expression of CMT3-2 in Nicotiana benthamiana (NbCMT3-2) and its significance by analyzing plants with silenced NbCMT3-2 and leaf tissues transiently expressing the N-terminal polypeptide. Alignment of the NbCMT3-2 amino acid sequence with that of other plant CMT3s showed a specific N-terminal extension required for nuclear localization. Transient expression of the N-terminal polypeptide in N. benthamiana resulted in chlorotic lesions. NbCMT3-2 was expressed mainly in proliferating tissues such as the shoot apex and developing leaves. We generated transgenic N. benthamiana harboring a fusion reporter construct linking the NbCMT3-2 promoter region and the ß-glucuronidase (GUS) reporter (pNbCMT3-2::GUS) to analyze the tissue-specific expression of NbCMT3-2. NbCMT3-2 was expressed in the shoot and root apical meristem and leaf primordia in young seedlings and highly expressed in developing leaves and ovary as well as lateral buds in mature plants. Virus-induced gene silencing used to knock down the expression of NbCMT3 or NbCMT3-2 or both led to partial loss of genomic DNA methylation. Plants with suppressed NbCMT3 expression grew and developed normally, whereas leaves with NbCMT3-2 knockdown showed mild curling as compared with controls. Silencing NbCMT3/3-2 severely interfered with leaf development and directly or indirectly affected the expression of genes involved in jasmonate homeostasis. The differential roles of NbCMT3 and NbCMT3-2 were investigated and compared. We reveal the expression patterns of NbCMT3-2 in proliferating tissues. NbCMT3-2 may play an essential role in leaf development by modulating jasmonate pathways.


Assuntos
DNA (Citosina-5-)-Metiltransferases/genética , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Especificidade de Órgãos/genética , Proteínas de Plantas/genética , Tabaco/enzimologia , Tabaco/genética , Sequência de Aminoácidos , Núcleo Celular/metabolismo , Clonagem Molecular , DNA (Citosina-5-)-Metiltransferases/química , DNA (Citosina-5-)-Metiltransferases/metabolismo , Metilação de DNA/genética , DNA Complementar/genética , Flores/genética , Flores/crescimento & desenvolvimento , Inativação Gênica , Genes de Plantas , Glucuronidase/metabolismo , Dados de Sequência Molecular , Organogênese/genética , Filogenia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Brotos de Planta/genética , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas , Transporte Proteico , Alinhamento de Sequência , Frações Subcelulares/metabolismo , Tabaco/crescimento & desenvolvimento
14.
Mycorrhiza ; 25(6): 431-45, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25575732

RESUMO

The medicinal effects and techniques for cultivating Anoectochilus formosanus are well-documented, but little is known about the mycorrhizal fungi associated with A. formosanus. Rhizoctonia (Thanatephorus) anastomosis group 6 (AG-6) was the most common species isolated from fungal pelotons in native A. formosanus and represented 67% of the sample. Rhizoctonia (Ceratobasidium) AG-G, P, and R were also isolated and represent the first occurrence in the Orchidaceae. Isolates of AG-6, AG-R, and AG-P in clade I increased seed germination 44-91% and promoted protocorm growth from phases III to VI compared to asymbiotic treatments and isolates of AG-G in clade II and Tulasnella species in clade III. All isolates in clades I to III formed fungal pelotons in tissue-cultured seedlings of A. formosanus, which exhibited significantly greater growth than nonmycorrhizal seedlings. An analysis of the relative effect of treatment ([Formula: see text]) showed that the low level of colonization ([Formula: see text]) by isolates in clade I resulted in a significant increase in seedling growth compared to isolates in clades II (0.63-0.82) and III (0.63-0.75). There was also a negative correlation (r = -0.8801) with fresh plant weight and fungal colonization. Our results suggest that isolates in clade I may represent an important group associated with native populations of A. formosanus and can vary in their ability to establish a symbiotic association with A. formosanus. The results presented here are potentially useful for advancing research on the medicinal properties, production, and conservation of A. formosanus in diverse ecosystems.


Assuntos
Micorrizas/classificação , Micorrizas/isolamento & purificação , Orchidaceae/microbiologia , Plantas Medicinais/microbiologia , Rhizoctonia/classificação , Rhizoctonia/isolamento & purificação , Biomassa , Micorrizas/fisiologia , Desenvolvimento Vegetal , Rhizoctonia/fisiologia , Plântula/microbiologia , Sementes/microbiologia , Simbiose
15.
Molecules ; 19(9): 14080-93, 2014 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-25207714

RESUMO

Phalaenopsis is the most important economic crop in the Orchidaceae family. There are currently numerous beautiful and colorful Phalaenopsis flowers, but only a few species of Phalaenopsis have an aroma. This study reports the analysis volatile components present in P. Nobby's Pacific Sunset by solid-phase microextraction (SPME) coupled with gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS). The results show that the optimal extraction conditions were obtained by using a DVB/CAR/PDMS fiber. A total of 31 compounds were identified, with the major compounds being geraniol, linalool and α-farnesene. P. Nobby's Pacific Sunset had the highest odor concentration from 09:00 to 13:00 on the eighth day of storage. It was also found that in P. Nobby's Pacific Sunset orchids the dorsal sepals and petals had the highest odor concentrations, whereas the column had the lowest.


Assuntos
Flores/química , Orchidaceae/química , Extratos Vegetais/isolamento & purificação , Adsorção , Microextração em Fase Sólida , Compostos Orgânicos Voláteis/isolamento & purificação
16.
Ecotoxicol Environ Saf ; 104: 36-42, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24632121

RESUMO

The phytotoxic effects of excess copper (Cu) on grapevines (Vitis vinifera L. var. Kyoho) were examined, both from macroscopic and microscopic perspectives, by using a fifteen-day hydroponic experiments. The influence of magnesium (Mg) on Cu phytotoxicity to, and accumulation and translocation in grapevines was also observed. For phytotoxicity effect, results showed that a relative low median growth inhibition level of Cu was found for grapevine roots (0.809-3.671µM). Moreover, Cu toxicity was significantly alleviated by Mg treatment at Mg(2+) activity between 0.15 and 2.01mM. For accumulation and translocation effects, results indicated that competition for binding sites between Cu and Mg occurred for roots; however, Mg and Cu levels in stems and leaves were not affected by solution metals concentration. At Cu concentration less than 1µM, the translocation of Cu was decreased significantly for the highest Mg treatment; at Cu concentrations greater than 5µM, no obvious change was observed in leaf TF value between Mg treatments, while an increasing trend of stem TF value was observed with increasing Mg. These results suggest that the toxic effect resulted from metals depend not only on the competition of coexistent cations for plasma membrane surface, but also on the transport and distribution of toxic metals in physiological active sites in plants.


Assuntos
Cobre/metabolismo , Cobre/toxicidade , Magnésio/farmacologia , Vitis/efeitos dos fármacos , Vitis/metabolismo , Cátions/farmacologia , Cobre/análise , Hidroponia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Caules de Planta/efeitos dos fármacos , Caules de Planta/metabolismo , Vitis/crescimento & desenvolvimento , Poluentes Químicos da Água/toxicidade
17.
Physiol Plant ; 150(1): 119-32, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23683172

RESUMO

DNA methylation is essential for normal developmental processes and genome stability. DNA methyltransferases are key enzymes catalyzing DNA methylation. Chromomethylase (CMT) genes are specific to the plant kingdom and encode chromodomain-containing methyltransferases. However, the function of CMT genes in plants remains elusive. In this study, we isolated and characterized a CMT gene from Nicotiana benthamiana, designated NbCMT3. Alignment of the NbCMT3 amino acid sequence with other plant CMT3s showed conservation of bromo-adjacent-homology and methyltransferase catalytic domains. We investigated the expression patterns of NbCMT3 and its function in developmental programs. NbCMT3 was expressed predominately in proliferating tissues such as apical shoots and young leaves. NbCMT3 protein showed a nuclear location, which could be related to its putative cellular functions. Knocking down NbCMT3 expression by virus-induced gene silencing revealed its vital role(s) in leaf morphogenesis. The formation of palisade cells was defective in NbCMT3-silenced plants as compared with controls. NbCMT3 has a role in developmental programs.


Assuntos
DNA (Citosina-5-)-Metiltransferases/metabolismo , Tabaco/enzimologia , Sequência de Aminoácidos , DNA (Citosina-5-)-Metiltransferases/isolamento & purificação , Metilação de DNA , Inativação Gênica , Dados de Sequência Molecular , Organogênese Vegetal , Fenótipo , Folhas de Planta/citologia , Folhas de Planta/crescimento & desenvolvimento , Proteínas de Plantas/isolamento & purificação , Proteínas de Plantas/metabolismo , Análise de Sequência de DNA , Tabaco/crescimento & desenvolvimento
18.
Bot Stud ; 55(1): 44, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28510937

RESUMO

BACKGROUND: Cyrtosia javanica is a rare, mycoheterotrophic vanilloid orchid native to the bamboo forest in central Taiwan. Like some vanilloid orchids, the seeds of C. javanica are hard and difficult to germinate in vitro. A better understanding of the embryology would provide insights in the propagation and conservation of this rare species. RESULTS: Based on the histological and histochemical studies, we observed some remarkable features in developing seeds of C. javanica. First, the developing embryos without a structurally defined suspensor; Second, the chalazal accessory cells have densely stained cytoplasms that are different from the adjacent cells of seed coat; Third, the multiple layers of seed coat with the lignified in the outermost cell layer of the outer seed coat. CONCLUSIONS: In C. javanica, the large and heavy seeds embedded in fresh fruits may adapt to the dispersal strategy. The hard seeds with lignified outer seed coat could provide a rigid protection during seed dispersal but also cause coat-imposed dormancy. This study provides insights in the seed coat structure and the hints of seed treatment methods.

19.
Plant Physiol Biochem ; 73: 375-82, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24211513

RESUMO

We assessed the effects of background concentrations of calcium (Ca) in solution on rhizotoxicity of copper (Cu) in and the accumulation and translocation of Cu by the grapevine, Vitis vinifera L. var. Kyoho. Grapevine cuttings in a hydroponic system were exposed to Cu-spiked solutions (0, 1, 2.5, 5, 10, and 25 µM) with two Ca backgrounds (0.5 and 5 mM) for 15 days. We found that when Cu exposure exceeded 5 µM, no new white roots were generated from the cuttings. When exposed to a Cu concentration of 25 µM, the lateral roots were sparse, appeared dark and exhibited malformed terminal swellings. The morphological phenomena of root response to an increase in Cu levels were relatively pronounced at a background concentration of 5 mM Ca; epidermal cell walls thickened, cortical cells remained intact and root terminal swelling was enhanced with Cu exposure. A 5 mM Ca background concentration enhanced the reduction in relative root elongation, but alleviated the reduction in relative root dry weight with increased Cu exposure. Moreover, there was a prominent increase in root Cu concentrations with increased Cu exposure, but the increases in leaf Cu concentrations were much less. The Cu profile of Cu exposure in a 5 mM Ca background concentration appeared higher in root, but lower in leaf than the Cu profile in a 0.5 mM Ca background; therefore, increase of Ca background concentrations would enhance Cu to be accumulated by root, but not translocated into the leaf.


Assuntos
Cálcio , Cobre , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Vitis/efeitos dos fármacos , Transporte Biológico/efeitos dos fármacos , Cálcio/metabolismo , Cálcio/farmacologia , Cobre/metabolismo , Cobre/toxicidade , Hidroponia , Meristema , Casca de Planta , Epiderme Vegetal , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Vitis/metabolismo
20.
Am J Bot ; 100(11): 2240-9, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24190948

RESUMO

PREMISE OF THE STUDY: We posed two hypotheses for broad scenarios of postglacial recolonization of Korea by the warm-temperate vegetation: (1) that extant Korean populations are derived from a single refugium, or (2) that they are derived from multiple refugia. We chose a homosporous fern typical of East Asian warm-temperate vegetation, Selliguea hastata, to test which of the two scenarios is more likely and to check whether Japan contained putative glacial refugia. METHODS: Using 16 allozyme loci, we obtained genotypes of 756 individuals from 20 populations, representative of the whole distribution area in Korea (including Jeju Island), Japan, and Taiwan. We assessed genetic variability within and among populations, Wright's F-statistics, and conducted analysis of molecular variance, model-based Bayesian clustering, and bottleneck tests. KEY RESULTS: We found no allozyme variation within populations of S. hastata in mainland Korea, whereas genetic polymorphism was detected for populations from Jeju Island, Japan (in particular a population from southeastern Shikoku), and Taiwan. The levels of inbreeding within populations were high, consistent with the potential of S. hastata for intragametophytic selfing. CONCLUSIONS: Data on allelic richness together with Bayesian clustering methods suggest a pattern of postglacial recolonization of mainland Korea from a single refugium, probably located either on Jeju Island or in Japan. Jeju Island should merit the highest priority for conservation biogeography, as it played a role as a Quaternary refugium for arctic-alpine, boreal, temperate as well as warm-temperate plants, as suggested here.


Assuntos
Variação Genética , Polypodiaceae/genética , Teorema de Bayes , Conservação dos Recursos Naturais , Eletroforese , Endogamia , Ilhas , Isoenzimas/genética , Isoenzimas/metabolismo , Japão , Dados de Sequência Molecular , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Polypodiaceae/metabolismo , República da Coreia , Análise de Sequência de DNA , Taiwan
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