排序方式: 共有25条查询结果,搜索用时 15 毫秒
1.
2.
Thermoperiodic effect on flowering and endogenous hormonal status in Dendrobium (Orchidaceae) 总被引:3,自引:0,他引:3
Two year-old cloned plants of Dendrobium Second Love were submitted to 25 °C (light) and 10 °C (dark) under a 12 h photoperiod (60 μmol m−1 s−1) for 30 days. The endogenous levels of IAA, ABA, and the cytokinins Z, [9R]Z, iP, and [9R]iP were measured 15, 22, and 30 days after the start of the thermoperiodic treatment in lateral buds and leaves. The endogenous levels of IAA and cytokinins, especially the zeatin-derived forms, increased significantly in buds after 15 days of treatment. On the other hand, the amount of ABA decreased progressively and significantly throughout the treatment. The treatment conspicuously accelerated flower-bud development. The found correlation suggests that hormones are involved in the signal transduction pathway of thermoperiodic flowering control. 相似文献
3.
Rosete Pescador Gilberto Barbante Kerbauy Wagner de Melo Ferreira Eduardo Purgatto Rogério Mamoru Suzuki Miguel Pedro Guerra 《Plant Growth Regulation》2012,68(1):67-76
Endogenous levels of IAA, ABA and four types of CKs were analyzed in zygotic and indirect (ISE) and direct somatic embryogenesis of Acca sellowiana. Zygotic and somatic embryos at different developmental stages were sampled for morphological and hormonal analysis. Both embryo types showed substantial asymmetry in hormone levels. Zygotic embryos displayed a conspicuous peak of IAA in early developmental stages. The results outlined the hormonal variations occurring during zygotic and somatic embryogenesis regarding the timing, nature and hormonal status involved in both processes. The short transient pulse of IAA observed on the 3rd day in culture was suggested to be involved with the signaling for the induction of somatic embryogenesis. Fertilized ovule development was associated with increased IAA levels 21?C24?days after pollination, followed by a sharp decrease in the cotyledonary stage, both in zygotic and somatic embryos. There was a prominent increase in ABA levels in cultures which generated ISE 24?C30?days after pollination, a period that corresponds to the heart and torpedo stages. The levels of total CKs (Z, [9R]Z, iP and [9R]iP) were also always higher in zygotic than in somatic embryogenesis. While zygotic embryogenesis was dominated by the presence of zeatin, the somatic process, contrarily, was characterized by a large variation of the other cytokinin forms and amounts studied. The above results, when taken together, could be related to the previously observed high frequency formation of anomalous somatic embryos formed in A. sellowiana, as well as to their low germination ability. 相似文献
4.
Rosete Pescador Gilberto Barbante Kerbauy Déborah Yara Alves Cursino dos Santos Lírio Luiz Dal Vesco Hugo Pacheco de Freitas Fraga Miguel Pedro Guerra 《Acta Physiologiae Plantarum》2012,34(2):771-778
Somatic embryogenesis is an in vitro morphogenetic route in which isolated cells or a small group of somatic cells give rise
to bipolar structures resembling zygotic embryos. Lipids, carbohydrates, and proteins are major compounds in plant and animal
metabolism. Comparative analysis along different developmental stages of Acca sellowiana (Myrtaceae) zygotic and somatic embryos, revealed a progressive increase in levels of total lipids. A high degree of similarity
could be found in the total lipids composition between A. sellowiana somatic and zygotic embryos. High lipid levels were found in zygotic embryos in the torpedo and cotyledonary stages, and
these levels increased according to the progression in the developmental stages. Somatic embryos obtained through direct embryogenesis
route showed higher levels of lipids than in indirect somatic embryogenesis. The compounds most frequently were linoleic acid
(C18:2), palmitic (C16:0) and oleic (C18:1). These results indicate a high similarity degree of accumulation of total lipids,
regardless of zygotic or somatic embryogenesis. 相似文献
5.
Endogenous contents of indolyl-3-acetic acid (IAA) and abscisic acid (ABA) were quantified in excised roots of Catasetum fimbriatum (Orchidaceae) cultured in vitro on solidified Vacin and Went medium with 1, 2, 4, 6, 8 and 10 % sucrose, as well as 2 % sucrose plus mannitol. Maximum root
growth was observed in media with 4 % sucrose and 2 % sucrose plus 2.2 % mannitol, suggesting that a moderate water or osmotic
stress promotes orchid root growth. Contents of both ABA and IAA increased in parallel to increasing sucrose concentration
and a correlation between root elongation and the ABA/IAA ratio was observed. Incubating isolated C. fimbriatum roots with radiolabeled tryptophan, we showed an accumulation of IAA and its conjugates. 相似文献
6.
Maria Aurineide Rodrigues Luciano Freschi Eduardo Purgatto Vera Fátima Gomes Alves Pereira Lima Gilberto Barbante Kerbauy 《Journal of Plant Growth Regulation》2014,33(3):513-525
The epiphytic habitat is potentially one of the most stressful environments for plants, making the effective developmental control in response to external cues critical for epiphyte survival. Because ethylene mediates several abiotic stresses in plants, here, we have examined the ethylene influence in both shoot and root systems of the epiphytic orchid Catasetum fimbriatum. Under controlled conditions, ethylene production was quantified during an entire growth cycle of C. fimbriatum development in vitro, while treatments modulating either ethylene concentration or perception were carried out over the early growth phase of these plants. After treatments, growth measurements and histological features were studied in both shoot and root tissues. Ethylene production showed a decreasing trend over the period of organ elongation; however, it increased considerably when leaves were shed, and a new axillary bud was initiating. The early exposure of young plants to higher concentrations of ethylene triggered morphogenic responses that included root hair formation instead of velamen, and a combination of inhibitory effects (decreases in both stem enlargement and cellular/organ elongation) and inductive effects (increases in leaf and root formation, bud initiation and cellular thickening) on plant growth, which favored biomass allocation to roots. Conversely, inhibition of ethylene perception over the plant growth phase generally resulted in the opposite morphogenic responses. Our data indicate that periodic variations in ethylene concentration and/or sensitivity seem to modulate several developmental features in shoot and root systems of C. fimbriatum which could have adaptive significance during the growing phase of this epiphytic orchid. 相似文献
7.
Shoot initiation and development was observed in Catasetum (Orchidaceae) cultured on hormone-free media. Endogenous auxin and cytokinin contents were determined in excised root tips
of two Catasetum fimbriatum genotypes incubated in a hormone-free medium. During the culture period, significant accumulation of all measured cytokinins
was observed in the isolated root tips of both genotypes, reducing, by the 10th day of incubation, the auxin/cytokinin ratio
tenfold in both genotypes. Root excision and the competence for shoot development in C. fimbriatum may be attributable to the establishment of an endogenous auxin/cytokinin ratio favoring cytokinins.
Received: 20 August 1998 / Revision received: 30 January 1999 / Accepted: 15 February 1999 相似文献
8.
Endogenous Levels of Cytokinins, Indoleacetic Acid, Abscisic Acid, and Pigments in Variegated Somaclones of Micropropagated Banana Leaves 总被引:4,自引:0,他引:4
The banana (Musa spp. AAA) micropropagation shows a high incidence of off-types, among whose variegated plants are very common. Endogenous
levels of growth regulators and pigment content were measured in normal and variegated leaves of the micropropagated banana
plants growing in a greenhouse. Growth regulators were separated by high pressure liquid chromatography and submitted to enzyme-linked
immunosorbent assay for quantification. Pigment content was measured using the colorimetric method. Green leaves contained
1.9 and 10 times more cytokinins compared with green and yellow sectors of variegated leaves, respectively. The levels of
indoleacetic acid in normal leaves were significantly higher than those found in green and yellow sectors of variegated leaves;
however, the levels of abscisic acid were lower in normal leaves. The lower content of chlorophylls in variegated leaves coincided
with decreased endogenous levels of cytokinins, which indicated that variegation in banana leaves may be associated with alterations
in the metabolism of this growth regulator.
Received December 3, 1997; accepted February 2, 1998 相似文献
9.
Maria Aurineide Rodrigues Alejandra Matiz Aline Bertinatto Cruz Aline Tiemi Matsumura Cassia Ayumi Takahashi Leonardo Hamachi Lucas Macedo Félix Paula Natália Pereira Sabrina Ribeiro Latansio-Aidar Marcos Pereira Marinho Aidar Diego Demarco Luciano Freschi Helenice Mercier Gilberto Barbante Kerbauy 《Annals of botany》2013,112(1):17-29
Background and Aims
A positive correlation between tissue thickness and crassulacean acid metabolism (CAM) expression has been frequently suggested. Therefore, this study addressed the question of whether water availability modulates photosynthetic plasticity in different organs of two epiphytic orchids with distinct leaf thickness.Methods
Tissue morphology and photosynthetic mode (C3 and/or CAM) were examined in leaves, pseudobulbs and roots of a thick-leaved (Cattleya walkeriana) and a thin-leaved (Oncidium ‘Aloha’) epiphytic orchid. Morphological features were studied comparing the drought-induced physiological responses observed in each organ after 30 d of either drought or well-watered treatments.Key Results
Cattleya walkeriana, which is considered a constitutive CAM orchid, displayed a clear drought-induced up-regulation of CAM in its thick leaves but not in its non-leaf organs (pseudobulbs and roots). The set of morphological traits of Cattleya leaves suggested the drought-inducible CAM up-regulation as a possible mechanism of increasing water-use efficiency and carbon economy. Conversely, although belonging to an orchid genus classically considered as performing C3 photosynthesis, Oncidium ‘Aloha’ under drought seemed to express facultative CAM in its roots and pseudobulbs but not in its leaves, indicating that such photosynthetic responses might compensate for the lack of capacity to perform CAM in its thin leaves. Morphological features of Oncidium leaves also indicated lower efficiency in preventing water and CO2 losses, while aerenchyma ducts connecting pseudobulbs and leaves suggested a compartmentalized mechanism of nighttime carboxylation via phosphoenolpyruvate carboxylase (PEPC) (pseudobulbs) and daytime carboxylation via Rubisco (leaves) in drought-exposed Oncidium plants.Conclusions
Water availability modulated CAM expression in an organ-compartmented manner in both orchids studied. As distinct regions of the same orchid could perform different photosynthetic pathways and variable degrees of CAM expression depending on the water availability, more attention should be addressed to this in future studies concerning the abundance of CAM plants. 相似文献10.
Rosete Pescador Gilberto B. Kerbauy Jane E. Kraus Wagner de Melo Ferreira Miguel Pedro Guerra Rita de Cássia L. Figueiredo-Ribeiro 《In vitro cellular & developmental biology. Plant》2008,44(4):289-299
Comparative analysis of zygotic and somatic embryogenesis of Acca sellowiana showed higher amounts of sucrose, fructose, raffinose, and myo-inositol in zygotic embryos at different developmental stages than in corresponding somatic ones. These differences were
mostly constant. In general, glucose levels were significantly lower than the other soluble carbohydrates analyzed, showing
minor variation in each embryo stage. Despite the presence of sucrose in the culture medium, its levels conspicuously diminished
in somatic embryos compared with the zygotic ones. Raffinose enhanced parallel to embryo development, regardless of its zygotic
or somatic origin. Analysis of the soluble carbohydrate composition of mature zygotic cotyledon used as explant pointed out
fructose, glucose, myo-inositol, sucrose, and raffinose as the most important. Similar composition was also found in the corresponding somatic cotyledon.
Total soluble carbohydrates varied inversely, decreasing in zygotic embryos and increasing in somatic embryos until the 24th
d, at which time they increased rapidly about sixfold in zygotic embryos until the 27th d, a period coinciding with the zygotic
proembryos formation. Such condition seems to reflect directly the variation of endogenous sucrose level, mainly because glucose
and fructose diminished continuously during this time period. This means that, in terms of soluble sugars, zygotic embryo
formation occurred under a situation represented by high sucrose amounts, simultaneously with low fructose and glucose levels,
while in contrast, somatic embryo formation took place under an endogenous sugar status characterized by a substantial fructose
enhancement. Starch levels increased continuously in zygotic embryos and decreased in somatic ones, the reverse to what was
found in fructose variation. Starch accumulation was significantly higher in somatic torpedo and cotyledonary embryos than
in the corresponding zygotic ones. 相似文献