Zygotic and somatic embryos of cucumber (Cucumis sativus L.) substantially differ in their levels of abscisic acid (original) (raw)
Related papers
Acta Physiologiae Plantarum, 2003
The influence of abscisic acid (ABA) on the processes of formation of different polysomal populations, their structures and stability in embryonal tissue during pea seeds germination was studied. The contents of total ribosomal fraction increased in all samples up to 72 h of germination and then decreased. The contents of polysomal population (FP, MBP, CBP and CMBP) extracted from the embryonal tissue after 72 hrs of germination of pea seeds were then quantified. It turned out that in examined tissue of control sample, fraction of free polysomes (FP) was the most abounded. This population of polysomes in sprouts decreased after ABA treatment. FP content decreased even more when the higher ABA concentration was applied during germination. Similar changes were observed in the fraction of membrane-bound polysomes (MBP). Quite different tendencies were found, however, in forming population of the cytoskeleton-membrane-bound polysomes (CMBP). The CMBP population content in embryonal tissue increased in a dosage dependent manner with increasing concentration of ABA applied during seed germination. This indicates the important role of CMBP fraction in synthesis of specific proteins in embryos in the time when processes of seeds germination are retarded by ABA. In the final part we examined the stability of polysomes isolated from sprouts of germinating seeds in water and sprouts isolated from seeds treated with ABA (100 µM) during germination. Total polysomes isolated from embryonal tissue of germinating seeds treated with ABA showed much higher resistance to exogenous ribonuclease digestion than total polysomes of control sample. The obtained results suggest that ABA influence on different polysomal population formation also controls their stability.
Planta, 1982
Abscisic acid (ABA) in extracts of somatic embryos and seeds of Gloryvine (Vitis vinifera L. x V. rupestris Scheele) was measured by gas chromatography-mass spectrometry-selected ion monitoring using deuterated ABA, (+)-[C-3Me-2H3]ABA, ([2H3]ABA) as internal standard. The ABA content increased rapidly during embryogeny (0.035 ng/embryo at the globular stage to 0.22 ng/embryo at the mature stage). The level of ABA in the tissues of somatic embryos, expressed in ng/mg dry weight, decreased from the globular stage (0.76 ng/mg) to the mature stage (0.25 ng/mg). Chilling (4 ~ C) induced normal germination of seeds and mature somatic embryos and precocious germination of globular, heart-shaped and torpedoshaped somatic embryos. In all cases chilling led to a marked reduction in endogenous ABA. Exogenous ( _+ )-ABA inhibited the germination of chilled somatic embryos.
Compartmentation of abscisic acid in developing muskmelon (Cucumis melo L.) seeds
Seed biology: advances and applications. Proceedings of the Sixth International Workshop on Seeds, Merida, Mexico, 1999., 2000
Abscisic acid levels vary dramatically during seed development, but little is known about changes in ABA compartmentation at the cellular and subcellular level. Soluble ABA was measured in developing muskmelon (Cucumis melo L.) endocarp, testa, endosperm, cotyledon, and embryonic axis tissue in fresh and dried seeds using an indirect enzyme-linked immunosorbant assay. Abscisic acid was visualized in immature 25 day after anthesis (DAA) and mature 55 (DAA) seed tissues at the subcellular level using transmission electron microscopy to detect gold particles conjugated to a polyclonal antibody raised against conjugated BSA-ABA. Soluble ABA concentrations were highest (250 ng g-1 DW) in embryonic axis tissue 25 (DAA) and corresponded with rapid dry weight accumulation and development of desiccation tolerance. Soluble ABA concentrations in the embryonic axis dropped rapidly to 25 ng g-1 DW at 55 DAA as seeds obtained maximum DW and developed full germinability. At 25 DAA, the highest density of gold particles was found in the nuclei, cytoplasm, and cell walls of the embryonic axis. In concert with the decline in ELISA measurements, the amount of gold labeling at 55 DAA was also reduced in embryonic axis tissue. Protein bodies were heavily labeled at 55 DAA, but little labeling was evident in the nucleus. Also at 55 DAA, labeling in the cytoplasm and cell wall was still evident. Our results, along with recent studies with pea and lavender, show that ABA accumulates in the nucleus during periods of active gene expression.
The effects of abscisic acid on the maturation ofBrassica napus somatic embryos
Protoplasma, 1993
A comparison of embryos, cultured for increasing periods of time with and without abscisic acid (ABA), was undertaken to investigate, at the ultrastructural level, the influence of this growth regulator on the maturation of rapeseed (Brassica napus) somatic embryos. In the absence of ABA, the embryos germinated precociously while lipid bodies (LB), which were not numerous, soon degraded, as revealed by a depletion process associated with the appearance of morphologically mature glyoxysomes and an increase in the number of mitoehondria. Moreover, a lack of protein bodies indicated that storage protein accumulation was not initiated under these conditions. On the contrary, the addition of ABA (10gM) induced marked modification of embryo metabolism. Indeed, ABA completely prevented precocious embryo germination and inhibited lipid reserve catabolism. Moreover, the formation of small vacuoles and proliferation of rough endoplasmie reticulum in their vicinity suggested the onset of storage protein accumulation. After 15 days in the presence of ABA, the embryos contained abundant lipid and protein bodies. Nevertheless, these somatic embryos were not exactly the same as their mature zygotic counterparts since differences were found in chloroplasts, amyloplasts, and nuclear structures. These observations suggest that additional factors might be required to obtain fully mature somatic embryos.
Abscisic acid in seed dovelopment and germination of carrot
2014
Os níveis de ácido abscísico (ABA) em sementes de cenoura (Daucus carota L.) oriundas de umbelas primárias e secundárias durante o desenvolvimento e a maturação foram determinados pela cromatografia líquida gasosa e relacionados com o crescimento e a germinação das sementes. O nível de ABA determinado foi alto durante o desenvolvimento da semente, alcançando o máximo aos 21-28 DAF, decrescendo rapidamente na maturação. O alto teor de ABA endógeno durante o desenvolvimento não afetou o crescimento da semente e a germinação; entretanto, a viabilidade da semente de ambas as posições foi completamente bloqueada na presença de 10-4 M ABA exógeno. Isto indica que o ABA pode apresentar dois mecanismos específicos de ação: um estimulador durante a embriogenese e o outro inibidor durante a remobilização. Os dados demonstraram, pela primeira vez em plantas umbelíferas, o nível de ABA endógeno na semente durante o desenvolvimento e o seu efeito na germinação.The levels of abscisic acid (ABA) i...
Journal of Experimental Botany, 2005
Abscisic acid (ABA) markedly reduced the germination of developing seeds at much lower concentrations (ABA 50 50.1 mM) compared with that of mature seeds (ABA 50 51.6 mM) in cucumber (Cucumis sativus L. cv. Green long). The perisperm-endosperm (PE) envelope in developing seeds showed partly differentiated lipid and callose layers, considerable ABA biosynthetic activity in endosperm cells, and appreciable permeability to applied ABA. The decrease in the sensitivity of seeds to applied ABA was coincident with the complete development of lipid and callose layers, diminished ABA biosynthetic activity in endosperm cells in imbibed mature seeds, and moderate permeability of the PE envelope to applied ABA. Decoated seeds pretreated with chloroform showed decreased germination (ABA 50 50.4 mM) in response to applied ABA and increased ABA permeation through the PE envelope. ABA thus allowed to permeate into embryonic tissues substantially reduced the pregerminative activity of b-glucanase in the radicles. The structure and biophysical/biochemical properties of the PE envelope seem to modulate the effect of ABA on the germination of developing and mature cucumber seeds.
Plant Physiology, 1990
Free abscisic acid (ABA) content in suspensors, embryos, and integuments was determined during seed development of Phaseolus coccineus. A highly specific and sensitive solid-phase radioimmunoassay based on a monoclonal antibody raised against free (S)-ABA was used for ABA quantification. Very small amounts of ABA were detected in the suspensor during initial stages of development; later two peaks of ABA occurred. Levels of ABA in the embryo and integument show a coincident triphasic distribution: two maxima in ABA content occurred when the embryo was 11 to 12 and 15 to 16 millimeters in length; later, when the embryo was 19 to 20 millimeters long, a further increase was observed. The role of ABA in runner bean seeds is discussed in relation to the development of the different seed tissues.