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1.
Ion antagonism in phytochrome-mediated calcium-dependent germination of turions of Spirodela polyrhiza (L.) Schleiden 总被引:1,自引:0,他引:1
The light-dependent germination response of turions (resting fronds) is mediated by phytochrome and requires the presence
of Ca2+ in the medium (K.-J. Appenroth and H. Augsten, 1990, Photochem. Photobiol. 52: 61–65). The Ca2+ requirement of germination is apparent only in the presence of exogenous Mg2+. A competitive ion antagonism was demonstrated between Ca2+ and Mg2+ in this physiological response; Mg2+ could also be replaced by Ba2+ or Sr2+. Without exog-enous Mg2+, a Ca2+ concentration as low as 0.9 μM fulfilled the Ca2+ requirement. This type of ion antagonism resembled the competitive Ca/Mg interaction reported previously for calcium-binding
proteins. The physiological response was blocked by inhibitors of Ca2+ uptake (verapamil, La3+). It was concluded that uptake of Ca2+ from the external medium is an essential step in the phytochrome-mediated germination of turions. The results are in agreement
with the assumption that the uptake of Ca2+ is blocked at the side of entry by other alkaline earth ions. Treatment of turions with Mg2+ (1 mM) for 24 h at varying times after the red light pulse in otherwise virtually Ca2+-free KNO3 solution resulted in a response similar to a Ca2+ step-down treatment. This is in agreement with the assumption that the Ca2+- and the Mg2+-sensitive periods coincide. The ion interaction described here represents the first photophysiological example in plants
of an antagonistic effect between Ca2+ and Mg2+ similar to that which occurs in vitro with calmodulin.
Received: 12 June 1998 / Accepted: 28 December 1998 相似文献
2.
Potamogeton crispus is a cosmopolitan aquatic species and is widely used as a pioneer species for vegetation restoration of eutrophic lakes.
However, many restoration projects applying P. crispus turions have not been successful. Earlier studies focused on effects of light and temperature on turion germination. The
purpose of this study was to determine whether sediment anoxia and light interactively affected the turion germination and
early growth of P. crispus. Anoxic conditions in the experiment were produced by adding sucrose to the sediment. The germination rate of the turions
was 68–73% lower in the highly anoxic condition treatment than in the control. Medium light intensity (10% of natural light
at the water surface) was more favorable for germination under slightly anoxic conditions than either low or high light intensity.
The growth of newly-formed sprouts was also significantly inhibited by sediment anoxia. Photosynthesis and shoot biomass were
reduced under sediment anoxia, whereas total chlorophyll content, root biomass, and soluble protein content were highest in
the low anoxic condition treatment. Medium light improved net photosynthesis and biomass production of the sprouts. We conclude
that turion germination and sprout growth can be significantly inhibited by sediment anoxia. Medium light intensity may alleviate
this inhibition by anoxia, but light has little effect when sediment anoxia is severe. For the purposes of vegetation restoration,
more attention should be paid to the role of sediment anoxia, and it is necessary to improve sediment and light conditions
for turion germination and early growth of P. crispus in eutrophic lakes. These results will contribute to a more complete understanding of turion germination dynamics of P. crispus and will be useful for future restoration programs.
Handling editor: S. M. Thomaz 相似文献
3.
Hidenobu Kunii 《Journal of plant research》1982,95(2):109-124
The life cycle and growth ofPotamogeton crispus L. were studied in a shallow pond, Ojaga-ike. With respect to the shoot elongation and seed and turion formations, the life
cycle of this plant in the pond could be divided into following five stages: germination, inactive growth, active growth,
reproductive and dormant stages. It was suggested that the plant showed these successive stages depending mainly upon water
temperature. The turions germinated on the bottom in autumn when the water temperature fell below ca. 20 C. The plant showed
hardly any growth during winter (December—early March) when the temperature was below 10 C. In the spring when the bottom
water temperature rose to above 10 C (mid-March), the plant started to grow again and the shoot elongated rapidly at the rate
of 4.2 cm day−1 until the shoot apex reached the pond surface in late April. Both the increment of node number and the internodal elongation
were associated with this rapid shoot growth. On 10 May (last sampling date), the mean values of shoot length, internodal
length and the number of nodes estimated for 10 predominant plants were 238.2±5.6 cm, 7.1±0.8 cm and 34.9±4.0 cm, respectively.
The turion formation and flowering occurred during the period from mid-April to mid-May when the surface water temperature
ranged 19 and 22 C. The dry weight of a plant reached the maximum mean value of 1180 mg on 10 May. At its peak biomass, an
individual plant produced 1–10 turions (5.5 on average) of which the mean individual turion dry weight was 53.2 mg. The turion
dry weight accounted for ca. 42% of the total plant biomass m−2 at that time. 相似文献
4.
光和基质对菹草石芽萌发、幼苗生长及叶片光合效率的影响 总被引:1,自引:0,他引:1
通过室内模拟试验,研究了基质和光照对菹草石芽萌发、幼苗生长以及不同光照对菹草生长后期叶片光合效率的影响.结果表明,在光照和缺乏基质的条件下,菹草石芽的萌发率和出苗率提高.基质的存在促进了根的生长,而光对根的生长并未起到促进作用.在无光条件下, 菹草幼苗节间长度明显大于有光处理.在暗处理中, 菹草叶片的质膜透性显著增加.在有光照条件下,有无基质对菹草幼苗叶片叶绿素a(Chla)、叶绿素b(Chlb)以及Chla/Chlb比值的影响为Chla、Chlb的含量增高,Chla/Chlb比值在3.5上下波动;Chla/Chlb最大值和最小值在有基质时分别为4.4和2.8,无基质时为4.2和2.7.但对幼苗处理40 d时,暗处理的叶片质膜透性与有光有基质、有光无基质之间差异极显著(P<0.01).不同光照处理(自然光、50%自然光、20%自然光和10%自然光)的光合特性差异比较结果表明,在菹草生长后期,在自然光下菹草叶片的Fv/Fm和Fv/Fo的比值与其它3个遮光处理相比存在显著差异(P<0.05),而在3个遮光处理之间差异不显著.进一步比较Fv/Fm、Fv/Fo、ETR、qP、qN和ΦPSⅡ等荧光参数值的结果显示,在生长的后期,一定程度的弱光会起到促进菹草的光合效率、延缓菹草衰老的作用. 相似文献
5.
RENEE GOLDBERG 《Physiologia plantarum》1980,50(3):261-264
The turions of Potamogeton crispus L. develop in early summer and function in propagation and dispersal. Under natural conditions during longday periods, an average minimum air temperature of more than 12°C was found to be important for turion formation. Experiments with controlled environments indicate that both temperature and photoperiod regulate turion formation. Turions can be induced at 13°C or above but not at 8 or 10°C. At a temperature range of 13–24°C turions form in both 12- and 16-h days, but not in 8-h days. By increasing temperature from 24 to 30 or 35°C turions can be induced under 8-h days. Light intensity was found to be important in the formation of turions. 相似文献
6.
In response to abscisic acid (ABA), the duckweed Spirodela polyrrhiza (L.) activates a developmental pathway that culminates in the formation of dormant structures known as turions. Levels of
the mRNA encoding d-myo-inositol-3-phosphate synthase (EC.5.5.1.4) which converts glucose-6-phosphate to inositol-3-phosphate, increase early in
response to ABA. In order to understand the role of this enzyme in turion formation, we have investigated changes in inositol
metabolism in ABA-treated plants. Here, we show that ABA-treatment leads to a 3-fold increase in free inositol, which peaks
2 d after treatment. This increase is followed by sequential increases in inositol phosphates and in accumulation of inositol
hexakisphosphate (InsP6), in particular. In addition, we observed an early increase in a novel inositol bisphosphate which is not directly on the
pathway to InsP6. In control plants, we observed synthesis and turnover of both inositol pentakisphosphate and InsP6. Two compounds more polar than InsP6 (diphosphoinositol polyphosphates) were present in both ABA-treated and control plants. Together, this suggests that the
role of InsP6 in plants may be more complex than simply that of a storage compound during dormancy.
Received: 10 January 2000 / Accepted: 25 February 2000 相似文献
7.
8.
Soetikno S. Sastroutomo 《Journal of plant research》1980,93(4):265-273
Effects of environmental conditions and growth regulators on release from dormoncy of axillary turions inHydrilla verticillata were investigated.
Coll treatment at 2 C for 33 days produced the most complete release from dormancy. One week of 2 C treatment was sufficient
for the germination; however, longer cold periods produced more rapid growth in shoot or root lengths as well as a shorter
lag time for germination.
Dormancy in turions could be broken by a photoperiod of 16 hr but not by on of 8 or 12 hr, nor by continuous lighting. When
a cold treatment was applied turions grew out in response to all of the photoperiodic conditions.
Red and far-red irradiation during the incubation after a cold treatment promoted gremination; blue and green light markedly
inhibited the germination.
At 10−4 and 10−5 M, gibberellic acid broke dormancy of non-cold treated turions, but was toxic at 10−4 M to the development after germination. Gibberellic acid promoted growth of cold treated turions even at 10−6 M. Indoleacetic acid at 10−4, 10−5 and 10−6 M induced outgrowth of both non-cold treated and cold treated turions. Apparently normal growth and development was observed
in a high concentration of indoleacetic acid. 相似文献
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