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1.
Cadmium elevates level of protein, amino acids and alters activity of proteolytic enzymes in germinating rice seeds 总被引:10,自引:0,他引:10
When seeds of two rice cvs. Ratna and Jaya were germinated under increasing levels of cadmium nitrate (0, 100 and 500 μM) in the medium, a marked decrease
in germination percentage was observed with Cd treatments, as compared to controls. There was more absorbed Cd in embryo axes
than in endosperms. More uptake resulted with increasing Cd levels in the growth medium in embryo axes. In both rice cultivars,
during a germination period of 0 – 120 h, an increased level of protein as well as free amino acids was noted in Cd treatments.
Protease activity in general decreased in both embryo axes as well as endosperms due to Cd treatment. In vitro studies showed an enhancement in protease activity in Cd treatments at low Cd levels (50–100 μM), whereas concentrations
above this caused inhibition in enzyme activity. Under 500 μM Cd treatments in vivo there was about 30 to 50 percent decline in leucine aminopeptidase (LAP) activity in endosperms, however, carboxypeptidase
activity showed a marked increase in endosperms beyond 24 h under Cd treatments. In embryo axes of germinating seeds there
was always a decline in peptidase activities, under the influence of cadmium. The leucine amino peptidase and protease activity
were always greater in embryo axes in cv. Ratna than cv. Jaya. However, the carboxypeptidase activity was higher in Jaya when compared to Ratna in endosperms under Cd treatments.
The results suggest possible suppression of protease and peptidase activities due to Cd treatments in germinating rice seeds
leading to altered levels of protein and amino acids. 相似文献
2.
Arsenic (As) is a potential contaminant of groundwater as well as soil in many parts of the world. The effects of increasing
concentration of As (25 μm and 50 μm As2O3) in the medium on the content of starch and sugars and activity levels of enzymes involved in starch and sugar metabolism
i.e. α-amylase, β-amylase, starch phosphorylase and acid invertase were studied in germinating seeds of two rice cvs. Malviya-36 and Pant-12 during 0–120 h period. As toxicity in situ led to a marked decline in the activities of α-amylase, β-amylase in endosperms as well as embryoaxes of germinating rice
seeds. The activity of acid invertase increased in endosperms as well as embryoaxes whereas starch phosphorylase activity
declined in endosperms but increased in embryoaxes under As treatment. In endosperms a decline in starch mobilization was
observed under As toxicity, however under similar conditions the content of total soluble sugars increased in embryoaxes.
The observed inhibition in activities of amylolytic enzymes might contribute to delayed mobilization of endospermic starch
which could affect germination of seeds in As polluted environment, while the induced acid invertase activity and increased
sugar accumulation in embryoaxes could serve as a possible component for adaptation mechanism of rice seedlings grown under
As containing medium. 相似文献
3.
Nickel toxicity inhibits ribonuclease and protease activities in rice seedlings: protective effects of proline 总被引:1,自引:0,他引:1
Seedlings of two rice cvs Malviya-36 and Pant-12, when grown under increasing levels of nickel (Ni2+: 200 and 400 μM) in the nutrient medium, showed increased levels of RNA, soluble proteins and free amino acids, especially
proline over a total growth period of 5–20 days. Ribonuclease (RNase) and protease activities decreased in both roots and
shoots due to Ni treatment in situ. Under in vitro conditions, a gradual inhibition of RNase activity was observed with increasing
concentrations of Ni2+ (0–2500 μM) in the assay medium. Artificial desiccation simulated by 40% PEG or the presence of 2.5 mM Ni2+ in the reaction medium resulted in about 52–53% loss of RNase activity. Such a loss could be partially restored by 1 M proline
in the assay medium. The activity staining of RNase revealed seven and four isoforms of RNase in roots and shoots, respectively.
The intensity of most of the bands decreased with increasing levels of Ni2+ treatment in situ. The results suggest that Ni toxicity in rice seedlings suppresses the hydrolysis of RNA and proteins by
inhibiting the activity of RNase and protease, respectively. Proline appears to act as a protectant of the enzyme RNase against
metal- and PEG-induced damages. 相似文献
4.
A. Dell'Aquila 《Biologia Plantarum》2004,48(2):237-242
Following 16, 40 and 64 h exposure to 0.33 M NaCl given after 8 h water imbibition, lentil seeds showed a gradual decrease
of germination upon their transfer to water. These salt related changes were accompanied by modifications in the protein patterns
of embryo axes as revealed by two-dimensional electrophoresis separation and by the computer image analysis of protein spots.
In comparison with 8 h water imbibed seeds, prominent proteins comprised between the 5.1 – 7.6 pH isoelectric point in the
first dimension and 75 – 50 kDa molecular mass in the second dimension showed a significant increase in their abundance as
salt exposure increased. On transfer to water to complete germination, the content of many of these proteins decreased at
24h in 2 – 3 cm length embryo axes in comparison with the corresponding embryo axes of seeds continuously imbibed in water
for 24 h. Some groups of proteins ranging between 15.5 – 17.3 kDa, already present after 8 h water imbibition, were not detectable
after 24 h but were expressed in seeds exposed to NaCl and transferred to water for 24 h. Up- and down-regulated proteins
in lentil embryo axes, imbibed under non-lethal salt stress conditions, have been tentatively identified by comparison with
the protein map of germinating seeds of the model plant Arabidopsis.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
Huabing Meng Shujin Hua Imran Haider Shamsi Ghulam Jilani Yuanlong Li Lixi Jiang 《Plant Growth Regulation》2009,58(1):47-59
Because of its prolific growth, oilseed rape (Brassica napus L.) can be grown advantageously for phytoremediation of the lands contaminated by industrial wastes. Therefore, toxic effect
of cadmium on the germination of oilseed rape, the capability of plants for cadmium phytoextraction, and the effect of exogenous
application of plant growth regulators to mitigate phytotoxicity of cadmium were investigated. For the lab study of seedlings
at early stage, seeds were grown on filter papers soaked in different solutions of Cd2+ (0, 10, 50, 100, 200 and 400 μM). In greenhouse study, seedlings were grown in soil for 8 weeks, transferred to hydroponic
pots for another 6 weeks growth, and then treated with plant growth regulators and cadmium. Four plant growth regulators viz.
jasmonic acid (12.5 μM), abscisic acid (10 μM), gibberellin (50 μM) and salicylic acid (50 μM); and three levels of Cd2+ (0, 50 and 100 μM) were applied. Data indicated that lower concentration of Cd2+ (10 μM) promoted the root growth, whereas the severe stresses (200 or 400 μM) had negative effect on the establishment of
germinating seedlings. Plants treated with any of the tested plant growth regulators alleviated cadmium toxicity symptoms,
which were reflected by more fresh weight, less malondialdehyde concentration in leaves and lower antioxidant enzyme activities.
The application of abscisic acid to the plants cultivated in the medium containing 100 μM Cd2+ resulted in significantly lower plant internal cadmium accumulation.
Huabing Meng and Shujin Hua contributed equally to this paper. 相似文献
6.
Seedlings of rice (Oryza sativa L.) cv. Pant-12 grown in sand cultures containing 200 and 400 μM NiSO4, showed a decrease in length and fresh weight of roots and shoots. Nickel was readily taken up by rice seedlings and the
concentration was higher in roots than shoots. Nickel-treated seedlings showed increased rates of superoxide anion (O2
•−
) production, elevated levels of H2O2 and thiobarbituric acid reactive substances (TBARS) demonstrating enhanced lipid peroxidation, and a decline in protein thiol
levels indicative of increased protein oxidation compared to controls. With progressively higher Ni concentrations, non-protein
thiol and ascorbate (AsA) increased, whereas the level of low-molecular-weight thiols (such as glutathione and hydroxyl-methyl
glutathione), the ratio of these thiols to their corresponding disulphides, and the ratio of AsA to dehydroascorbic acid declined
in the seedlings. Among the antioxidant enzymes studied, the activities of all isoforms of superoxide dismutase (Cu-Zn SOD,
Mn SOD and Fe SOD), guaiacol peroxidases (GPX) and ascorbate peroxidase (APX) increased in Ni-treated seedlings, while no
clear alteration in catalase activity was evident. Activity of the ascorbate-glutathione cycle enzymes monodehydroascorbate
reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR)—significantly increased in Ni-treated
seedlings. However such increase was apparently insufficient to maintain the intracellular redox balance. Results suggest
that Ni induces oxidative stress in rice plants, resulting in enhanced lipid peroxidation and decline in protein thiol levels,
and that (hydroxyl-methyl) glutathione and AsA in conjunction with Cu-Zn SOD, GPX and APX are involved in stress response. 相似文献
7.
The present study was undertaken to examine the influence of toxic levels of Ni and Al, on the activities of key nitrogen
assimilatory enzymes in roots and shoots of growing rice seedlings. When seedlings of two inbred rice (Oryza sativa L.) cvs. Malviya-36 and Pant-12, sensitive to both Ni and Al, were raised in sand cultures containing 200 and 400 μM NiSO4 or 80 and 160 μM Al2(SO4)3, a marked inhibition in the activities of NO3
− assimilatory enzymes NR and GS was observed in roots as well as shoots during a 5–20 day growth period. Both Ni and Al treatments,
in growth medium, stimulated the activity of aminating glutamate dehydrogenase (NADH-GDH) whereas the activity of deaminating
GDH (NAD+-GDH) decreased under metal toxicities. The activities of the aminotransferases studied; alanine aminotransferase (AlaAT)
and aspartate amino transferase (AspAT) increased due to Ni and Al treatments. Results suggest that both Ni and Al treatments
impair N assimilation in rice seedlings by inhibiting the activities of NR and GS and that GDH appears to play a role in assimilation
of NH4
+ in metal stress conditions. Further, higher activity of aminotransferases in metal stressed seedlings might be helpful in
meeting higher demand of amino acids under stressed conditions. 相似文献
8.
K. Samuel D. Debashish B. Madhumita G. Padmaja Siva Ram Prasad V. Bhaskara Ramana Murthy P. S. Rao 《In vitro cellular & developmental biology. Plant》2009,45(4):466-473
The propagation of Givotia rottleriformis Griff. is difficult as a result of long seed dormancy associated with poor seed germination. The present study was undertaken
to develop a protocol to overcome seed dormancy by culture of zygotic embryo axes and then develop an efficient method for
micropropagation of Givotia. Best germination frequency (78.3%) was achieved from mature zygotic embryo axes isolated from acid-scarified fresh seeds
when cultured on Murashige and Skoog (MS) medium (half-strength major salts) with 28.9 μM gibberellic acid (GA3). Efficient plant conversion was achieved by transfer of 10-d-old germinated embryos to MS medium (half-strength major salts)
supplemented with 1.2 μM kinetin (KN) and 0.5 μM indole-3-butyric acid (IBA). However, acid scarification of 1-yr-old seeds
decreased the germination frequency of zygotic embryo axes in comparison to those obtained from non-acid-scarified seeds which
germinated (96.2%) and converted into plants (80.3%) on MS basal (half-strength major salts) medium. Multiple shoot bud induction
was achieved by culture of shoot tips derived from in vitro germinated seedlings on MS medium with 0.5 μM thidiazuron for 4 wk, and the shoots elongated after transfer to a secondary
medium with 1.2 μM KN. A maximum number of 7.8 shoots per explant with an average shoot length of 3.2 cm was achieved after
two subcultures on this medium. The in vitro regenerated shoots rooted (41.5%) on half-strength MS medium with 0.5 μM IBA. The in vitro generated seedlings and micropropagated plants were established in soil with a survival frequency of 70% and 60%, respectively. 相似文献
9.
Involvement of oxidative stress and role of antioxidative defense system in growing rice seedlings exposed to toxic concentrations of aluminum 总被引:6,自引:0,他引:6
When seedlings of rice (Oryza sativa L.) cultivar Pant-12 were raised in sand cultures containing 80 and 160 μM Al3+ in the medium for 5–20 days, a regular increase in Al3+ uptake with a concomitant decrease in the length of roots as well as shoots was observed. Al3+ treatment of 160 μM resulted in increased generation of superoxide anion (O2
−) and hydrogen peroxide (H2O2), elevated amount of malondialdehyde, soluble protein and oxidized glutathione and decline in the concentrations of thiols
(-SH) and ascorbic acid. Among antioxidative enzymes, activities of superoxide dismutase (SOD EC 1.15.1.1), guaiacol peroxidase
(Guaiacol POX EC 1.11.1.7), ascorbate peroxidase (APX EC 1.11.1.11), monodehydroascorbate reductase (MDHAR EC 1.6.5.4), dehydroascorbate
reductase (EC 1.8.5.1) and glutathione reductase (EC 1.6.4.2) increased significantly, whereas the activities of catalase
(EC EC 1.11.1.6) and chloroplastic APX declined in 160 μM Al3+ stressed seedlings as compared to control seedlings. The results suggest that Al3+ toxicity is associated with induction of oxidative stress in rice plants and among antioxidative enzymes SOD, Guaiacol POX
and cytosolic APX appear to serve as important components of an antioxidative defense mechanism under Al3+ toxicity. PAGE analysis confirmed the increased activity as well as appearance of new isoenzymes of APX in Al3+ stressed seedlings. Immunoblot analysis revealed that changes in the activities of APX are due to changes in the amounts
of enzyme protein. Similar findings were obtained when the experiments were repeated using another popular rice cv. Malviya-36. 相似文献
10.
Haoru Tang Zhenglong Ren Gari Krczal 《In vitro cellular & developmental biology. Plant》2000,36(1):47-50
Summary Well-developed somatic embryos were selected from a repetivively somatic embryo line derived from embryonic axes of immature
zygotic embryos of English walnut ‘No. 120’ (Juglans regia L.) for germination and conversion studies. In germinating dishes, somatic embryos germinated into only shoots, only roots,
or both shoots and roots. Without any pretreatment, 28% somatic embryos germinated, while those treated with 2.5–5.0 mg 1−1 (7.2–14.4 μmol) gibberellic acid (GA3) germinated at 25–28% and those receiving a cold treatment of 2–3 mo. at 3–4°C germinated at 30–43%. However, only 4–19%
of the germinating embryos showed both shoots and roots. Treated with desiccation, either with CaCl2·6H2O or Ca(NO3)2·4H2O at 20°C in the dark for 3 d, somatic embryos germinated at 85–91%, 57–69% of which had both shoots and roots. Treatment
with 2 mo. cold storage in combination with desiccation using Ca(NO3)2·4H2O resulted in 92% of somatic embryos germinating, 70% of which showed both shoots and roots. No significant differences were
observed between solid and liquid germination media. After transferring the germinating embryos to plantlet development media,
52–63% of those with both shoots and roots developed into plantlets while 11% with only shoots or 9% with only roots converted
into plantlets. Plantlet development was improved by using lower medium salts and sucrose concentrations. The addition of
activated charcoal enhanced root development, particularly root branching. Of 131 plants transplanted, 91 plants were acclimatized
to a greenhouse. 相似文献
11.
Changes in ascorbate and glutathione contents and the activities and isoenzyme patterns of enzymes of the ascorbate-glutathione
cycle were investigated in embryo axes and cotyledons of germinating lupine (Lupinus luteus L.) seeds. Ascorbate content was not significantly affected over the initial 12 h of imbibition in embryo axes, but afterwards
increased, with the most rapid accumulation coinciding with radicle emergence. A somewhat similar trend was observed for glutathione
with significant increase in embryo axes shortly before radicle protrusion followed by decline in the next hours. In cotyledons
the ascorbate pool rose gradually during germination but the amount of glutathione showed fluctuations during a whole germination
period. The activity of ascorbate peroxidase (APX) rose progressively in embryo axes, while activities of dehydroascorbate
reductase (DHAR) and glutathione reductase (GR) showed transient increase during germination. New isoforms of APX and GR were
synthesized, suggesting that they play a relevant role during germination. All analyzed enzymes were already present in dry
seeds which allowed them to be active immediately after imbibition. 相似文献
12.
The effect of increasing concentrations of Al2(SO4)3 in situ on the content of starch, sugars and activity behaviour of enzymes related to their metabolism were studied in growing
seedlings of two rice cvs. Malviya-36 and Pant-12 in sand cultures. Al2(SO4)3 levels of 80 and 160 μM in the growth medium caused an increase in the contents of starch, total sugars as well as reducing
sugars in roots as well as shoots of the rice seedlings during a 5–20 days growth period. The activities of the enzymes of
starch hydrolysis α-amylase, β-amylase and starch phosphorylase declined in Al-exposed seedlings, whereas the activities of
sucrose hydrolyzing enzymes sucrose synthase and acid invertase increased in the seedlings due to Al3+ treatment. The enzyme of sucrose synthesis, sucrose phosphate synthase showed decreased activity in Al3+ treated seedlings compared to controls. Results suggest that Al3+ toxicity in rice seedlings impairs the metabolism of starch and sugars and favours the accumulation of hexoses by enhancing
the activities of sucrose hydrolyzing enzymes. 相似文献
13.
GALLESCHI L.; SPANO' C.; BEDINI G.; FLORIS C.; SAVIOZZI F.; CAPOCCHI A. 《Annals of botany》1988,61(1):93-97
Carboxypeptidase, aminopeptidase and proteinase activities weremeasured in endosperms from dry and germinating x Haynaldoticumsardoum naturally aged seeds. Carboxypeptidase activity, presentin dry seeds, decreased slightly during germination and remainednearly unchanged during the storage period. Aminopeptidase activityincreased during germination in younger seeds, but decreasedin non-viable seeds. Proteinase activity was absent in dry seeds,increased during germination in younger seeds and disappearedin the older ones. Proteinase activity was not recovered in old endosperms followingtransplantation of young embryos, and was recovered only toa very small extent in young endosperms following transplantationof old embryos. Young endosperms onto which young embryos hadbeen transplanted gave maximum recovery of enzyme activity,although this was lower than in young intact seeds. These results suggest that the reduced or delayed availabilityof nutrients to the embryo axis is not the only factor causingthe failure of seeds to germinate, the ageing process beinga progressive phenomenon affecting both embryo and endosperm. x Haynaldoticum sardoum, Denti de cani, seed ageing, proteolytic activities, embryo-transplantation 相似文献
14.
Sacred lotus (Nelumbo nucifera Gaertn. ‘Tielian’) seed is long-lived and extremely tolerant of high temperature. Water content
of lotus and maize seeds was 0.103 and 0.129 g H2O [g DW] −1, respectively. Water content, germination percentage and fresh weight of seedlings produced by surviving seeds gradually
decreased with increasing treatment time at 100°C. Germination percentage of maize (Zea mays L. ‘Huangbaogu’) seeds was zero after they were treated at 100°Cfor 15 min and that of lotus seeds was 13.5% following the
treatment at 100°C for 24 h. The time in which 50% of lotus and maize seeds were killed by 100°C was about 14.5 h and 6 min,
respectively. With increasing treatment time at 100°C, relative electrolyte leakage of lotus axes increased significantly,
and total chlorophyll content of lotus axes markedly decreased. When treatment time at 100°C was less than 12 h, subcellular
structure of lotus hypocotyls remained fully intact. When treatment time at 100°C was more than 12 h, plasmolysis gradually
occurred, endoplasmic reticulum became unclear, nuclei and nucleoli broke down, most of mitochondria swelled, lipid granules
accumulated at the cell periphery, and organelles and plasmolemma collapsed. Malondialdehyde (MDA) content of lotus axes and
cotyledons decreased during 0 −12 h of the treatment at 100°C and then increased. By contrast, the MDA content of maize embryos
and endosperms increased during 5–10 min of the treatment at 100°C and then decreased slightly. For lotus seeds: (1) activities
of superoxide dismutase (SOD) and glutathione reductase (GR) of axes and cotyledons and of catalase (CAT) of axes increased
during the early phase of treatment at 100°C and then decreased; and (2) activities of ascorbate peroxidase (APX) and dehydroascorbate
reductase (DHAR) of axes and cotyledons and of CAT of cotyledons gradually decreased with increasing treatment time at 100°C.
For maize seeds: (1) activities of SOD and DHAR of embryos and endosperms and of GR of embryos increased during the early
phase of the treatment at 100°C and then decreased; and (2) activities of APX and CAT of embryos and endosperms and of GR
of endosperms rapidly decreased with increasing treatment time at 100°C. With decrease in seed germination, activities of
SOD, APX, CAT, GR and DHAR of axes and cotyledons of lotus seeds decreased slowly, and those of embryos and endosperms of
maize seeds decreased rapidly. 相似文献
15.
Organogenic cultures were induced from zygotic embryo and megagametophyte explants of the Central American cycad species,
Dioon edule. Plant growth medium consisted of B5 major salts, Murashige and Skoog minor salts and organics, 400 mg l−1 glutamine, 100 mg l−1 arginine, 100 mg l−1 asparagine, 60 g l−1 sucrose, 8 g l−1 Difco Bacto agar and was supplemented with kinetin (0 – 13.94 μM) and 2,4-dichlorophenoxyacetic acid (2,4-D) (0 – 9.05 μM)
arranged as a 5×4 factorial in a randomized block design. Callus initiation occurred on a wide range of medium formulations
from megagametophyte explants; however, shoot formation occurred only on medium supplemented with 2.26 μM 2,4-D. In comparison,
callus initiation from explanted zygotic embryos occurred on fewer medium formulations, and adventitious shoot induction occurred
from callus on formulations with 9.29–13.94 μM kinetin + 0.45–9.05 μM 2,4-D. Rooted shoots, derived from megagametophyte and
zygotic embryo cultures, have been regenerated.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
Germination of lupine (Lupinus luteus L.) seeds was accompanied by an increase in concentration of free radicals with g
1
and g
2
values of 2.0056 ± 0.0003 and 2.0033 ± 0.0005, respectively. The highest intensity of free radical signal was observed in
embryo axes immediately after radicle protruded through the seed coat. Hydrogen peroxide accumulated in embryonic axes and
cotyledons during imbibition before the onset of germination in the seed population. The activities of superoxide dismutase
(SOD, EC 1.15.1.1) and catalase (CAT, EC 1.11.1.6) rose progressively in embryo axes. In cotyledons SOD activity did not change
significantly, while that of CAT increased during germination. The enhancement of Cu, Zn-SODs and Mn-SOD isoforms in embryonic
axes was observed. A new isoform of catalase was synthesized, suggesting that it plays a relevant role during germination.
SOD and CAT activities were detected in dry seeds. Free radical generation and response of antioxidative enzymes differed
between embryo axes and cotyledons during the germination timecourse. 相似文献
17.
Iwona Morkunas Magda Formela Łukasz Marczak Maciej Stobiecki Waldemar Bednarski 《Protoplasma》2013,250(1):63-75
Ascochyta pisi is a necrotrophic pathogenic fungus, which mainly survives between seasons through infected seeds. Defence responses of pea embryo axes to A. pisi were investigated in the heterotrophic phase of seed germination and during the transition from the heterotrophic to the autotrophic phase. Germinated pea seeds, both non-inoculated and inoculated with A. pisi, were cultured in perlite for 96 h. Polarographic studies performed on intact embryo axes of germinating pea seeds infected with A. pisi showed a high respiratory intensity in time from 48 to 96 h after inoculation. Forty-eight-hour embryo axes of germinating pea seeds exhibited the highest respiration rate, which in infected axes was maintained at the following time points after inoculation. Moreover, at 72 and 96 h after inoculation, respiratory intensity was by 64% and 73% higher than in the control. Electron paramagnetic resonance analysis revealed a higher concentration of semiquinone free radicals with g values of g ||?=?2.0031?±?0.0004 and g ⊥?=?2.0048?±?0.0004 in infected axes than in the control. Generation of superoxide anion radical was also higher in infected axes than in the control but stronger at 72 and 96 h after inoculation. Starting from 72 h after infection, the level of Mn2+ ions in infected axes decreased in relation to the control. At the same time, the highest activity of superoxide dismutase (EC 1.15.1.1) and catalase (EC 1.11.1.6) was observed in 72-h infected axes. In turn, the activity of peroxidase (EC 1.11.1.7) up to 72 h after infection was lower than in the control. In 48-h infected embryo axes, a very high level of pterocarpan pisatin was observed. Infection of germinating pea seeds with A. pisi restricted mainly the growth of the epicotyl, but did not inhibit the increase in length and fresh weight of root embryo axes versus cultivation time. These results indicate that in pea during the stages of seed germination and early seedling growth, protective mechanisms are induced in embryo axes against A. pisi. 相似文献
18.
Grand Rapids lettuce (Lactuca sativa L.) seeds were stored in an imbibed state for up to two years. Embryos dissected from stored seeds showed a progressive loss with time in their ability to germinate on polyethylene glycol (PEG) solutions. Little germination of dissected embryos from one-month imbibed seeds occurred on-6 bar PEG but only after four months of storage did the dissected embryos fail to germinate on-4 bar PEG. After two years storage 30% of dissected embryos still were able to germinate on-2 bar PEG. This loss of germination potential, which may be a symptom of the development of an embryo dormancy, could be reversed by N6-benzyladenine (BA) and red light (R) applied together or separately to dissected embryos. Two weeks of chilling of 12-month imbibed seeds restored sensitivity to R and a 48-h BA pretreatment prior to R resulted in germination rates similar to those of seeds emerging from primary dormancy. There was loss of embryo control of endo--mannanase activity after two weeks of storage even though the endosperms themselves retained their capacity for enzyme synthesis for six more weeks. Eventually, then, endo--mannanase synthesis is not possible because of inherent changes in both the embryo and endosperm, although each tissue undergoes changes at its own rate. Oxygen uptake by embryos dissected from two-month imbibed seeds did not increase to the same extent as embryos dissected from freshly imbibed seeds. In intact seeds germinating from a skotodormant state, oxygen uptake increased at a time coincident with radicle protrusion, but did not achieve the levels of uptake of those seeds germinating from a primary dormant state. The decline in uptake of oxygen by secondary dormant seeds is the result of a lowered respiratory capability of the embryo itself, rather than of changes in permeability of the surrounding structures.Abbreviations BA
N6-benzyladenine
- Pfr
active (far-redabsorbing) form of phytochrome
- R
red light
- PEG
polyethylene glycol 相似文献
19.
20.
Haiyan Bu Qingji Ren Xiuli Xu Kun Liu Peng Jia Shujun Wen Dashuai Sun Guozhen Du 《Frontiers of Biology in China》2008,3(2):187-193
The germination experiment was started on March 3, 2004, and seeds were collected from July to October in 2003. We analyzed
the percentage of germination, days to first germination, germination period and days to 50% germination. Among the 54 examined
species, 26 species exceeded 80% germination, 11 species exceeded 60%–80% germination, 8 exceeded 40%–0%, 5 exceeded 20%–40%,
and 4 showed less than 20%. A principal-component analysis revealed that the species were distributed along two statistically
independent axes, the first primarily represented the germination rate and the second represented the time of germination
process. Based on scores of germination characteristics, cluster analysis of the 54 gramineous species could be divided into
4 distinct groups: rapid, slow, intermediate germinating (germination percentage > 50%), and low germinating (germination
percentage < 50%). The meaning of different groups to the vegetation regeneration was discussed.
__________
Translated from Journal of Plant Ecology, 2006, 30(4): 624–632 [译自: 植物生态学报] 相似文献