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The role of the cell cycle machinery in resumption of postembryonic development 总被引:1,自引:0,他引:1 下载免费PDF全文
Barrôco RM Van Poucke K Bergervoet JH De Veylder L Groot SP Inzé D Engler G 《Plant physiology》2005,137(1):127-140
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Importance of methionine biosynthesis for Arabidopsis seed germination and seedling growth 总被引:11,自引:0,他引:11
Gallardo K Job C Groot SP Puype M Demol H Vandekerckhove J Job D 《Physiologia plantarum》2002,116(2):238-247
Proteomics of Arabidopsis seeds revealed the differential accumulation during germination of two housekeeping enzymes. The first corresponded to methionine synthase that catalyses the last step in the plant methionine biosynthetic pathway. This protein was present at low level in dry mature seeds, and its level was increased strongly at 1-day imbibition, prior to radicle emergence. Its level was not increased further at 2-day imbibition, coincident with radicle emergence. However, its level in 1-day imbibed seeds strongly decreased upon subsequent drying of the imbibed seeds back to the original water content of the dry mature seeds. The second enzyme corresponded to S -adenosylmethionine synthetase that catalyses the synthesis of S -adenosylmethionine from methionine and ATP. In this case, this enzyme was detected in the form of two isozymes with different p I and M r. Both proteins were absent in dry mature seeds and in 1-day imbibed seeds, but specifically accumulated at the moment of radicle protrusion. Arabidopsis seed germination was strongly delayed in the presence of dl -propargylglycine, a specific inhibitor of methionine synthesis. Furthermore, this compound totally inhibited seedling growth. These phenotypic effects were largely alleviated upon methionine supplementation in the germination medium. The results indicated that methionine synthase and S -adenosylmethionine synthetase are fundamental components controlling metabolism in the transition from a quiescent to a highly active state during seed germination. Moreover, the observed temporal patterns of accumulation of these proteins are consistent with an essential role of endogenous ethylene in Arabidopsis only after radicle protrusion. 相似文献
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Alicia Gamboa-deBuen Rocio Cruz-Ortega Eleazar Martínez-Barajas María Esther Sánchez-Coronado Alma Orozco-Segovia 《Physiologia plantarum》2006,128(3):520-530
Natural priming promotes fast and synchronic seed germination and enhances the establishment of seedlings from Wigandia urens seeds. In this study, seeds of this species were buried in the field in three different sites, and each site was divided into three different microsites (natural priming). They were then exhumed and air-dried at the beginning of the rainy season. The control and exhumed W. urens seeds were tested for differences in germination, and in the protein patterns derived from heat-stable and phospho-protein enriched fractions, sucrose concentrations, amylase isoenzyme patterns, as well as catalase activity and H2 O2 levels. All the exhumed seeds germinated faster and more synchronically than the control seeds. Nevertheless, the germinative pattern showed a microsite effect related to the microenvironmental conditions. Most exhumed samples kept the germinative advantages acquired from the soil during natural priming for 2 years but seeds from the most heterogeneous site (a forest gap) did not. Natural priming also promoted mobilization of 7-S globulin-like proteins, solubilization of the 11-S globulin-like proteins as well as sucrose consumption before radicle protrusion. Although there were no changes in starch concentration during the germination of either the control or buried seeds, a different isoenzyme amylase pattern was observed. Catalase activity decreased and hydrogen peroxide levels were lower in exhumed seeds during germination. The changes in the protein and sucrose patterns were related to advances in the germinative process acquired during burial. Metabolic advantages were maintained systematically in all seed samples along the 2 years. The ecological significance of natural priming is discussed. 相似文献
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Seed dormancy is a key adaptive trait in plants responsible for the soil seed bank. The long established hormone-balance theory describes the antagonistic roles of the dormancy promoting plant hormone abscisic acid (ABA), and the germination promoting hormone gibberellin (GA) in dormancy control. Light, temperature, and other dormancy-breaking signals function to modulate the synthesis and perception of these hormones in the seed. However, the way in which these hormones control dormancy in the imbibed seed remains unknown. Here, we show that the DELLA protein regulators of the GA response are required for dormancy and describe a model through which hormone signal integration and dormancy regulation is achieved. We demonstrate that cotyledon expansion precedes radicle emergence during Arabidopsis seed germination and that a striking correlation exists between final seedling cotyledon size and seed dormancy in the DELLA mutants. Furthermore, twelve previously characterized seed-dormancy mutants are also defective in the control of cotyledon size in a manner consistent with their effect on germination potential. We propose that DELLA-mediated, light-, temperature-, and hormone-responsive cotyledon expansion prior to radicle emergence overcomes dormancy imposed by the seed coat and underlies seed-dormancy control in Arabidopsis. 相似文献
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《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1998,321(8):705-711
Seed priming (controlled imbibition) is a widely used technique for improving crop establishment, because it allows a reduction of the time to radicle emergence following seed imbibition and synchronization of individual seeds within seed lots with respect to germination timing. The major problem encountered in seed priming is the control of seed imbibition to a level permitting pre-germinative processes to proceed but that blocks radicle emergence. If not, the consequence of drying back the seeds to initial moisture content for storage purposes could be a total loss of the treated batch. This is because, as long as radicle growth has not begun, seeds may be re-dried without any permanent deleterious effects upon subsequent germination or growth. Recently, we reported the discovery of a molecular marker of sugar beet seed priming, corresponding to the basic B-subunit of the seed storage protein 11S globulin. An ELISA based upon this molecular marker has been used to analyse how different sugar beet seed lots respond to a priming treatment. The results demonstrate that this ELISA allows us to readily distinguish between the primed seeds and the corresponding untreated seeds. 相似文献
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Vander Willigen C Postaire O Tournaire-Roux C Boursiac Y Maurel C 《Plant & cell physiology》2006,47(9):1241-1250
Extensive and kinetically well-defined water exchanges occur during germination of seeds. A putative role for aquaporins in this process was investigated in Arabidopsis. Macro-arrays carrying aquaporin gene-specific tags and antibodies raised against aquaporin subclasses revealed two distinct aquaporin expression programs between dry seeds and young seedlings. High expression levels of a restricted number of tonoplast intrinsic protein (TIP) isoforms (TIP3;1 and/or TIP3;2, and TIP5;1) together with a low expression of all 13 plasma membrane aquaporin (PIP) isoforms was observed in dry and germinating materials. In contrast, prevalent expression of aquaporins of the TIP1, TIP2 and PIP subgroups was induced during seedling establishment. Mercury (5 microM HgCl(2)), a general blocker of aquaporins in various organisms, reduced the speed of seed germination and induced a true delay in maternal seed coat (testa) rupture and radicle emergence, by 8-9 and 25-30 h, respectively. Most importantly, mercury did not alter seed lot homogeneity nor the seed germination developmental sequence, and its effects were largely reversed by addition of 2 mM dithiothreitol, suggesting that these effects were primarily due to oxidation of cell components, possibly aquaporins, without irreversible alteration of cell integrity. Measurements of water uptake in control and mercury-treated seeds suggested that aquaporin functions are not involved in early seed imbibition (phase I) but would rather be associated with a delayed initiation of phase III, i.e. water uptake accompanying expansion and growth of the embryo. A possible role for aquaporins in germinating seeds and more generally in plant tissue growth is discussed. 相似文献
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Cell cycle activity during seed priming is not essential for germination advancement in tomato 总被引:3,自引:1,他引:2
Seed priming is a technique of controlled hydration and drying that results
in more rapid gemination when the seeds are reimbibed. Advancement of
radicle meristem cells into the S and G2 phases of the cell cycle,
increasing the percentage of nuclei having a 4C DNA content, has been
reported to occur during priming. It has been suggested that the efficiency
of priming is related to the accumulation of 4C nuclei in the radicle
meristem, but the extent of cell cycle activity varied among different
treatments and seed lots. A wide range of priming treatments across
temperatures, water potentials and durations can be compared on a common
basis using the hydrothermal priming time model. Flow cytometry was used to
monitor cell cycle activity in a number of tomato (Lycopersicon
esculentum Mill.) seed lots during priming in relation to the
accumulation of hydrothermal priming time and the subsequent germination
rate response. In some seed lots, the percentage of 4C nuclei in the
radicle meristems prior to emergence increased in proportion to accumulated
hydrothermal priming time, while in other lots, no increase in nuclear DNA
content was detected. All lots, however, demonstrated rapid radicle
emergence following priming. Thus, replicative DNA synthesis in radicle
meristem nuclei often occurred during seed priming, but an increase in the
percentage of 4C nuclei was not essential for germination
advancement. 相似文献
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Seed dormancy is an important developmental process that prevents pre-harvest sprouting in many grains and other seeds. Abscisic acid (ABA), a plant hormone, plays a crucial role in regulating dormancy but the underlying molecular regulatory mechanisms are not fully understood. An Arabidopsis zinc-finger gene, MEDIATOR OF ABA-REGULATED DORMANCY 1 ( MARD1 ) was identified and functionally analyzed. MARD1 expression is up-regulated by ABA. A T-DNA insertion in the promoter region downstream of two ABA-responsive elements (ABREs) renders MARD1 unable to respond to ABA. The mard1 seeds are less dormant and germinate in total darkness; their germination is resistant to external ABA at the stage of radicle protrusion. These results suggest that this novel zinc-finger protein with a proline-rich N-terminus is an important downstream component of the ABA signaling pathway that mediates ABA-regulated seed dormancy in Arabidopsis. 相似文献
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Transcriptome- and proteome-wide analyses of seed germination 总被引:1,自引:0,他引:1
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《Autophagy》2013,9(5):838-839
Selective autophagy, mediated by Atg8 binding proteins, has not been extensively studied in plants. Plants possess a large gene family encoding multiple isoforms of the Atg8 protein. We have recently reported the identification of two new, closely homologous Arabidopsis thaliana plant proteins that bind the Arabidopsis Atg8f protein isoform. These two proteins are specific to plants and have no homologs in nonplant organisms. The expression levels of the genes encoding these proteins are elevated during carbon starvation and also during late stages of seed development. Exposure of young seedlings to carbon starvation induces the production of a newly identified compartment decorated by these Atg8-binding proteins. This compartment dynamically moves along the endoplasmic reticulum membrane and is also finally transported into the vacuole. Enhanced or suppressed expression of these Atg8-binding proteins respectively enhances or suppresses seed germination under suboptimal germination conditions, indicating that they contribute to seed germination vigor. 相似文献
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Selective autophagy, mediated by Atg8 binding proteins, has not been extensively studied in plants. Plants possess a large gene family encoding multiple isoforms of the Atg8 protein. We have recently reported the identification of two new, closely homologous Arabidopsis thaliana plant proteins that bind the Arabidopsis Atg8f protein isoform. These two proteins are specific to plants and have no homologs in nonplant organisms. The expression levels of the genes encoding these proteins are elevated during carbon starvation and also during late stages of seed development. Exposure of young seedlings to carbon starvation induces the production of a newly identified compartment decorated by these Atg8-binding proteins. This compartment dynamically moves along the endoplasmic reticulum membrane and is also finally transported into the vacuole. Enhanced or suppressed expression of these Atg8-binding proteins respectively enhances or suppresses seed germination under suboptimal germination conditions, indicating that they contribute to seed germination vigor. 相似文献