首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
S. Frosch  H. Mohr 《Planta》1980,148(3):279-286
Carotenoid accumulation in the cotyledons of the mustard seedling (Sinapis alba L.) is controlled by light. Besides the stimulatory function of phytochrome in carotenogenesis the experiments reveal the significance of chlorophyll accumulation for the accumulation of larger amounts of acrotenoids. A specific blue light effect was not found. The data suggest that light exerts its control over carotenoid biogenesis through two separate mechanisms: A phytochrome regulation of enzyme levels before a postulated pool of free carotenoids, and a regulation by chlorophyll draining the pool by complex-formation.Abbreviations Chl chlorophyll(s) - PChl protochlorophyll(ide) - HIR high irradiance reaction (of phytochrome) - Pfr far-red absorbing, physiologically active form of phytochrome - Pr red absorbing, physiologically inactive form of phytochrome - Pfof total phytochrome, i.e. [Pr]+[Pfr] - [Pfr]/[Pfof], wavelength dependent photoequilibrium of the phytochrome system - red red light - fr far-red light  相似文献   

2.
K. Malhotra  H. Oelze-Karow  H. Mohr 《Planta》1982,154(4):361-370
We have performed a comprehensive study on the mechanism of regulation of carotenogenesis by light in the shoot of Sorghum vulgare. Our work shows that carotenoid accumulation is simultaneously controlled by phytochrome (Pfr) and by the availability of chlorophyll. Throughout plastidogenesis light dependent chlorophyll and carotenoid accumulation are interdependent processes: Accumulation of chlorophyll in natural light requires the presence of carotenoids; likewise, accumulation of considerable amount of carotenoids depends on the availability of chlorophyll. However, in both cases the efficiency of the biosynthetic pathway, the potential biosynthetic rates (capacities) are determined by phytochrome. A push and pull model of carotenogenesis advanced previously (Frosch and Mohr 1980, Planta 148, 279) to explain carotenogenesis in the mustard (Sinapis alba) seedling also applies to the monocotyledonous milo (Sorghum vulgare) seedling. Therefore, we suggest that the model applies to carotenogenesis in higher plants in general.Abbreviations Chl chlorophyll(s) - PChl protochlorophyll(ide) - HIR High irradiance response (of phytochrome) - Pfr far-red absorbing, physiologically active form of phytochrome - P red absorbing physiologically inactive form of phytochrome - Ptot total phytochrome - i.e. [Pr]+[Pfr] =[Pfr]+[Ptot], wavelength dependent photoequilibrium of the phytochrome system - RL red light - FR far-red light  相似文献   

3.
A 1-min light pulse delivered to mustard seedlings (Sinapis alba L.) 60 h after sowing initiates the release of cotyledonary 5-aminolaevulinate (ALA) accumulation which continues for at least 2 h in the dark. Phytochrome (P fr) increases the rate of ALA accumulation after a 24-h red light pretreatment but is not the trigger for this release. It is shown that the rate of ALA accumulation varies with the wave-length and fluence rate of the 1-min light pulse and can be predicted from the degree of protochlorophyll-(ide) photoconversion. There is a linear correlation between the rate of ALA accumulation and the degree of protochlorophyll(ide) (PChl)chlorophyll(ide) a (Chl a) photoconversion in etiolated seedlings. In seedlings pretreated with red light this correlation is non-linear and the rate increases more rapidly with increasing degrees of PChlChl a photoconversion. It is suggested that there may exist an interaction between P fr and PChlChl a photoconversion in controlling ALA accumulation.Abbreviations ALA 5-aminolaevulinate - Chl chlorophyll(ide) - PChl protochlorophyll(ide) - cp cotyledon pair - LA laevulinate  相似文献   

4.
S. Frosch  H. Drumm  H. Mohr 《Planta》1977,136(2):181-186
Phytochrome controls the appearance of many enzymes in the mustard (Sinapis alba L.) cotyledons. The problem has been whether the effect of phytochrome on the appearance of enzymes in this organ is due to a common initial action of Pfr, e.g. due to the liberation of a second messenger. We have compared the modulation by light (phytochrome) of the appearance of phenylalanine ammonia lyase (PAL)+ and ribulosebisphosphate carboxylase (Carboxylase)+. PAL becomes detectable in the mustard cotyledons at 27 h after sowing while Carboxylase starts to appear only at 42 h after sowing (starting points, 25° C). The starting points cannot be shifted by light. As a major result, in the case of PAL the inductive effect of continuous red light (given from the time of sowing) remains fully reversible by 756 nm-light up to the starting point (27 h after sowing) while with Carboxylase full reversibility in continuous red light is lost at approximately 15 h after sowing. While the induction of Carboxylase is already saturated at a very low level of Pfr (e.g. continuous 756 nm-light saturates the response) and does not depend on irradiance (e.g. continuous 675 mW m-2 red light and 67.5 mW m-2 red light lead to the same time course), PAL induction is a graded response over a wide range of Pfr doses and depends strongly on the fluence rate (high irradiance response, HIR). It is concluded that PAL induction and Carboxylase induction are not only separated in time but differ in every regard except that both responses are mediated by phytochrome.The present data support the previous conclusion that the specification of the temporal and spatial pattern of development is independent of phytochrome even though the realization of the pattern of development can only occur in the presence of phytochrome (Pfr). It seems that there is no feedback from pattern realization to pattern specification.Abbreviations Pfr the far-red absorbing, physiologically active form of phytochrome - Pr the red absorbing physiologically inactive form of phytochrome - Ptotal [Pr]+[Pfr] - PAL phenylalanine ammonia-lyase (EC 4.3.1.5) - Carboxylase ribulosebisphosphate carboxylase (EC 4.1.1.39)  相似文献   

5.
A. Wildermann  H. Drumm  E. Schäfer  H. Mohr 《Planta》1978,141(2):211-216
After sowing, mustard (Sinapis alba L.) seedlings were grown for 48 h in white light (25°C). These fully de-etiolated, green seedlings were used as experimental material between 48 and 72 (84) h after sowing. The question researched was to what extent control by light of hypocotyl elongation is due to phytochrome in these seedlings. It was found that the light effect on hypocotyl growth is very probably exerted through phytochrome only. In particular, we found no indication for the involvement of a specific blue light photoreceptor pigment.Abbreviations HIR high irradiance reaction - Pfr far-red absorbing, physiologically active form of phytochrome - Pr red absorbing, physiologically inactive form of phytochrome - Pot total phytochrome, i.e. [Pr]+[Pfr] - [Pfr]/[Ptot] - red red light - fr far-red light - wl white light - bl blue light - di dichromatic irradiation - l hypocotyl length  相似文献   

6.
The time course of appearance of competence to phytochrome (Pfr) was studied in cotyledons of mustard (Sinapis alba L.) with regard to the light-mediated accumulation of mRNAs encoding for SSU, CAB and the 23 kDa protein of the oxygen evolving complex of photosystem II (OEC). For each gene family a specific starting point of Pfr-induced mRNA accumulation was observed (SSU: 42 h; CAB: 36 h; OEC: 30 h). An increase of SSU-mRNA levels can be detected 24 h after sowing in dark-grown seedlings whereas for OEC the time points for the increase of mRNA are the same whether the seedlings are kept in darkness or induced by light via Pfr. For all gene families a responsiveness to Pfr (coupling point) could be demonstrated before the starting points. The coupling points are also gene specific (SSU: ca. 12 h; CAB and 23 kDa peptide of OEC: ca. 24 h). The responsiveness to light before the starting point indicates that the light-induced signal must be stored.  相似文献   

7.
Phytochrome was studied spectrophotometrically in Avena sativa L. seedlings that had been grown for 6 d in continous white fluorescent light from lamps. Greening was prevented through the use of the herbicide San 9789. When placed in the light, phytochrome (Ptot) decreased with first order kinetics (1/2 2 h) but reached a stable low level (2.5% of the dark level) after 36 h. This concentration of phytochrome remained constant in the light and during the initial hours of a subsequent dark period, but increased significantly after a prolonged dark period. Evidence suggests that the constant pool of phytochrome in the light is achieved through an equilibrium between synthesis of the red absorbing (Pr) and destruction of the far-red absorbing form (Pfr) of phytochrome. It is concluded that the phytochrome system in light-grown oat seedlings is qualitatively the same as that known from etiolated monocotyledonous seedlings, but different than that described for cauliflower florets.Abbreviations Pfr the far-red light absorbing form of phytochroma - Pr the red light absorbing form of phytochrome - Ptot Pr+Pfr - ks rate constant of Pr synthesis - kd rate constant of Pfr destruction - MOPS N-morpholino-3-propane-sulfonic acid - IRIS Tris (hydroxymethyl) amino methane - San 9789 4-chloro-5-(methyl amino)-2-(,,-trifluoro-m-tolyl)-3(2H)pyridazinone  相似文献   

8.
Summary The rate of prenyl chain accumulation (C40 carotenoids; C45 in plastoquinone-9; C20 phytyl in chlorophylls, -tocopherol and vitamin K1) in plastids of etiolated radish seedlings (Raphanus sativus L.) is determined in continuous darkness and after far-red and white light treatment. Continuous far-red light (active phytochrome P fr ) stimulates the synthesis of all prenyl chains, but has no or only little effect on the dark pattern of the prenyl chain formation. White light enhances the accumulation of prenyl chains to a much higher degree than does far-red light. By a particularly strong promotion of the accumulation of phytyl chains, which are incorporated into chlorophyll, white light changes the percentage composition of prenyl chains to that of chloroplasts.  相似文献   

9.
Summary To follow changes in the status of phytochrome in green tissue and to relate these changes to the photoperiodic control of flowering, we have used a null response technique involving 1.5-min irradiations with mixtures of different ratios of R and FR radiation.Following a main photoperiod of light from fluorescent lamps that was terminated with 5 min of R light, the proportion of Pfr in Chenopodium rubrum cotyledons was high and did not change until the 3rd hour in darkness; at this time, Pfr disappeared rapidly. When the dark period began with a 5-min irradiation with BCJ or FR light to set the proportion of Pfr low Pfr gradually reappeared during the first 3 h of darkness and then disappeared again.The timing of disappearance of Pfr is consistent with the involvement of phytochrome in photoperiodic time measurement. Reappearance of Pfr after an initial FR irradiation explains why FR irradiations sometimes fail to influence photoperiodic time measurement or only slightly hasten time measurement. A R light interruption to convert Pr to Pfr delayed, the timer by 3 h but only for interruptions after and not before the time of Pfr disappearance. Such 5-min R-light interruptions did not influence the operation of the rhythmic timekeeping mechanism. Continuous or intermittent-5 min every 1.5 h-irradiations of up to 6 h in duration were required to rephase the rhythm controlling flowering. A skeleton photoperiod of 6 h that was began and terminated by 5 or 15 min of light failed to rephase the rhythm.The shape of the curves for the rhythmic response of C. rubrum to the length of the dark period are sometimes suggestive of clocks operating on the principle of a tension-relaxation mechanism. Such a model allows for separate timing action of a rhythm and of Pfr disappearance over the early hours of darkness. Separate timing action does not, however, preclude an interaction between the rhythm and phytochrome in controlling flowering.Abbreviations FR far-red - Pfr far-red-absorbing form of phytochrome - Pr red-absorbing form of phytochrome - R red - BCJ photographic ruby-red irradiation A grant in aid of research from the National Research Council of Canada to B. G. Cumming is gratefully acknowledged.  相似文献   

10.
H. Mohr  H. Drumm  R. Schmidt  B. Steinitz 《Planta》1979,146(3):369-376
Induction by light of phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) and of anthocyanin in cotyledons of the mustard (Sinapis alba L.) seedling is strongly affected by a light pretreatment which operates through phytochrome. If PAL or anthocyanin is induced by a light pulse, the effectiveness of phytochrome (Pfr) is strongly increased by a light pretreatment; however, if the increase of the PAL level or synthesis of anthocyanin is elicited by continuous far-red light (operating via phytochrome in the High Irradiance Response), effectiveness of light is strongly reduced by the same light pretreatment. This reduction of effectiveness is correlated with a decrease of total phytochrome (Ptot) caused by the light pretreatment. It is argued that the observations are compatible only with the open phytochrome-receptor model as suggested by Schäfer (J. Mathem. Biol. 2, 41–56, 1975). The peaks of the time courses of the PAL levels under continous far-red light are located at 48 h after sowing and do not depend on the original level of phytochrome. The decrease of the PAL levels beyond 48 h after sowing takes place independently of phytochrome and of the actual level of PAL.Abbreviations Pr red absorbing form of phytochrome - Pfr far-red absorbing form of phytochrome - Ptot total phytochrome (Pr+Pfr) - {ie369-1} [Pfr] /[Ptot], photoequilibrium of phytochrome at wavelength - HIR High Irradiance Response - PAL phenylalanine ammonialyase (EC 4.3.1.5)  相似文献   

11.
Coaction of three factors controlling chlorophyll and anthocyanin synthesis   总被引:1,自引:0,他引:1  
Helga Kasemir  Hans Mohr 《Planta》1982,156(3):282-288
In a three-factor analysis the rate of chlorophyll a (Chl) accumulation in excised mustard cotyledons was studied as a function of kinetin, light (operating through phytochrome, P fr) and an excision factor. It was found that the three factors operate additively provided that the P fr level is high enough. When the P fr level is below approximately 1 per cent (<0.01) the effectiveness of the excision factor decreases while the effect of kinetin remains additive. The observed additivity is explained by a model where the three factors operate independently through a common intermediate (presumably 5-aminolevulinate) in the biosynthetic chain leading to Chl. With regard to the coaction of the excision factor and phytochrome it is concluded that the production of the excision factor requires the operation of phytochrome (even though saturated at a low P fr level) while the action of the excision factor is independent of phytochrome. This conclusion was confirmed by experiments in which the rate of light-mediated anthocyanin synthesis was measured in excised mustard cotyledons. The effect of excision in the case of anthocyanin formation differs kinetically from the effect of excision on Chl formation.Abbreviations Chl chlorophyll(ide) a - P fr far-red absorbing form of phytochrome - P fr/P tot ratio at photoequilibrium - RL red light - FR far-red light - GL green light - RG9 light long wavelength far-red light - WL white light  相似文献   

12.
Photocontrol of stem elongation in light-grown plants of Fuchsia hybrida   总被引:1,自引:1,他引:0  
D. Vince-Prue 《Planta》1977,133(2):149-156
Stems of the caulescent long-day plant, Fuchsia hybrida cv Lord Byron, showed 2 types of response to light. In one, internode length was increased by far-red irradiation given at the end of an 8 h photoperiod: the response was no greater with prolonged exposure and was less when the start of far-red was delayed. The effect of far-red was reversible by a subsequent exposure to red light. Internode length was inversely proportional to the Pfr/P ratio established before entry to darkness and there was no evidence for loss of Pfr during a 16 h dark period. The inhibitory effect of Pfr acted at a relatively late stage of internode growth. With the development of successive internodes a second response appeared in which stems lengthened following prolonged daily exposures to red or far-red light, or mixtures of the two, or to brief breaks with red or white light. In these later internodes, a short exposure to far-red near the middle of the night was not reversible by red because red alone promoted elongation at this time. Internode length increased with increase in the daily duration of light and, when light was given throughout an otherwise dark period of 16 h, with increase in illuminance to a saturation value of 200 lx from tungsten lamps. Elongation increased as a linear function of decrease in photostationary state of phytochrome down to Pfr/P0.3; however, internodes were shorter in far-red light than in 25% red/red+far-red. It was concluded that stem length is a net response to two modes of phytochrome action. An inductive effect of Pfr inhibits a late stage in internode expansion, and a phytochrome reaction which operates only in light (and may involve pigment cycling) promotes an early stage of internode development. Stem elongation is thus a function both of the daily duration of light and its red/red+far-red content. The outgrowth of axillary buds was controlled by the first type of phytochrome action only.Abbreviations and symbols FR far red light - R red light - P phytochrome - Pfr phytochrome in the far-red light absorbing form - SD 8 h short days - LDP long-day plant - SDP short-day plant  相似文献   

13.
The in vivo properties of Amaranthus phytochrome   总被引:1,自引:1,他引:0  
Summary Phytochrome has been measured in etiolated seedling of Amaranthus caudatus. The phytochrome content increases from the time of germination until 72 hr from sowing, after which it remains constant at 27.5x10-3 (OD) units per 200 seedlings. After a saturating dose of red light P fr decays in the dark to a form not detectable photometrically. There is no evidence for the process of dark reversion of P fr to P fr found in other dicotyledons. Even in the presence of azide, a selective inhibitor of decay, the process of dark reversion is not observed. The decay of P fr has been investigated at different temperatures and follows first order decay kinetics throughout. Over the temperature range 15–30° the Q 10 of decay remained constant at 4.3.The photostationary states of phytochrome (P fr /P total )maintained by mixed red/far-red light have been measured in both seedlings and partially purified protein extracts, with good agreement. The rate of phytochrome decay can be manipulated by changing the P fr /P total ratio. The lag period before a decay curve becomes exponential is characteristic of a particular P fr /P total ratio and represents the time for attainment of the photostationary state. The effect of energy on decay has been investigated under red and blue light. The rate of phytochrome decay is dependent on the P fr /P total ratio and only becomes energy dependent when the light intensity is so low that the photostationary state is never attained.The process of apparent phytochrome synthesis has been found in Amaranthus. After reducing the phytochrome to a low level by red light treatment a rate of apparent synthesis of 1.35×10-4 (OD) units per hr per 200 seedlings was observed, levelling off at 29% of the original phytochrome level.Under white tungsten lights of high intensity there is a deviation from the expected first order decay kinetics. The nature of this low rate of decay cannot be explained at the present time.  相似文献   

14.
Abstract Mustard seedlings were light treated at 24 h after sowing (25°C) to induce phytochrome-mediated anthocyanin synthesis in cotyledons and hypocotylar hook. All light treatments were performed within the range of the reciprocity law. The in situ photoconversion kinetics of phytochrome (Pr→ Pfr) were measured under the same light treatment. It was found that between 0.4 and 1.0 relative Pfr level the amount of anthocyanin extracted from the organs at 52 h after sowing was linearily correlated with the amount of Pfr produced at 24 h in cotyledons and hypocotylar hook. It is concluded that an explanation of the fluence response function for red light mediated anthocyanin synthesis in the mustard seedling does not require the concept of active vs. bulk phytochrome.  相似文献   

15.
D. Marmé  B. Marchal  E. Schäfer 《Planta》1971,100(4):331-336
Summary During the first 10 min after a saturating dose of red light, 72 h dark-grown mustard cotyledons show no phytochrome decay. Within the same time interval there exists a transient form of P fr (=P fr T ) which is no longer photoconvertible at 0°C, but is at 25°C. This P fr T converts in the dark to P fr and P r . These dark reversions take about 10 min. After a lag phase of 10 min the P fr decay can be described by a single, first order kinetic curve. The time courses of these reactions are functions of the time of etiolation.Research supported by DAAD and by Deutsche Forschungsgemeinschaft (SFB 46).  相似文献   

16.
Germination of spores of Dryopteris fllix-mas has been induced by two pulses of saturating red light, separated by a dark period of about 8 to 24 h. By chosing different wavelengths, different Pfr/Ptot levels could be established. Thus, by a “null method” the second pulse could be used as a “test pulse”, determining the actual Pfr level remaining from the “start pulse”, and thus providing information about an apparent Pfr decay. It cannot be decided yet whether this apparent Pfr decay results from dark destruction or dark reversion. The apparent Pfr decay depends, as expected, on the temperature, being accelerated with increasing temperatures. Moreover, the later after sowing that the decay is tested, the faster it proceeds; a tentative interpretion is that newly synthesized Pr undergoes faster decay after phototransformation than that phytochrome pool present in the resting spores. A third factor that influences the apparent Pfr decay is the Pfr/Ptot level established by the first pulse (start pulse). The lower this level, the slower the decay kinetics. This could be due to phytochrome biosynthesis partly compensating for Pfr destruction, and the relative contribution of this biosynthesis to the total effect increases with lower Pfr levels. Spores of D. paleacea yield virtually the same results. Whatever the real basis of the observed Pfr decay, i.e. destruction, reversion, or a combination of these reactions with biosynthesis, it can be concluded that modification of this Pfr decay by various factors is the basis of the effect of those factors on light-induced germination.  相似文献   

17.
H. Kasemir  G. Prelim 《Planta》1976,132(3):291-295
Summary The rate of chlorophyllide esterification in mustard cotyledons can be increased by a pretreatment with 5 min red light applied 24 h prior to the protochlorophyll(ide)chlorophyll(ide) photoconversion at 60 h after sowing. Simultaneously the red light pulse pretreatment leads to a decrease of the total amount of chlorophyll(ide) a in darkness. It has been proven that phytochrome (Pfr) is the photoeffector for both. Since the amounts of esterified chlorophyllide are determined by the ratio [chlorophyll a]/[chlorophyllide a+chlorophyll a] it is assumed that Pfr increases the rate of esterification indirectly via stimulating the decrease of chlorophyll(ide) a. The regulation of chlorophyll synthesis by Pfr does not seem to involve a control of esterification. The duration of the chlorophyllide esterification differs from the duration of the Shibata shift although both are greatly shortened by the red light pulse pretreatment. The effect of 5 min red light on the duration of the esterification is fully reversible by 5 min far-red light while the reversibility with respect to the Shibata shift is lost within 2 min [Jabben, M. and H. Mohr, Photochem. Photobiol. 22, 55–58 (1975)]. We conclude that the control of the chlorophyllide esterification and the control of the Shibata shift cannot be traced back to the same initial action of Pfr.Abbreviations Chl chlorophyll - Chlide chlorophyllide - Chl(ide) sum of Chl and Chlide - PChl protochlorophyll - PChlide protochlorophyllide - PChl(ide) sum of PChl and PChlide - Pfr far-red absorbing form of the phytochrome system  相似文献   

18.
The low chlorophyll content of cotyledons of Pharbitis nil grown for 24 h in far-red light (FR) or at 18° C in white light from fluorescent lamps (WL) allows spectrophotometric measurement of phytochrome in these tissues. The (A) measurements utilize measuring beams at 730/802 nm and an actinic irradiation in excess of 90 s. The constancy of the relationship between phytochrome content and sample thickness confirms that, under these conditions of measurement, a true maximum phytochrome signal was obtained. These techniques have been used to follow changes in the form and amount of phytochrome during an inductive dark period for flowering. Following exposure to 24h WL at 18° C with a terminal 10 min red (R), Pfr was lost rapidly in darkness and approached zero in less than 1 h; during this period there was no change in the total phytochrome signal. Following exposure to 24 h FR with a terminal 10 min R, Pfr approached zero in 3 h, and the total phytochrome signal decreased by about half. The relevance of these changes to photoperiodic time measurement is discussed.Abbreviations BCJ irradiation from photographic ruby-red lamps - FR far-red light - Pfr far-red-absorbing form of phytochrome - Pr red-absorbing form of phytochrome - P total phytochrome content - R red light - WL white light from fluorescent lamps  相似文献   

19.

Main conclusion

Storage promotes carotenoid accumulation and converts amylochromoplasts into chromoplasts in winter squash. Such carotenoid enhancement is likely due to continuous biosynthesis along with reduced turnover and/or enhanced sequestration. Postharvest storage of fruits and vegetables is often required and frequently results in nutritional quality change. In this study, we investigated carotenoid storage plastids, carotenoid content, and its regulation during 3-month storage of winter squash butternut fruits. We showed that storage improved visual appearance of fruit flesh color from light to dark orange, and promoted continuous accumulation of carotenoids during the first 2-month storage. Such an increased carotenoid accumulation was found to be concomitant with starch breakdown, resulting in the conversion of amylochromoplasts into chromoplasts. The butternut fruits contained predominantly β-carotene, lutein, and violaxanthin. Increased ratios of β-carotene and violaxanthin to total carotenoids were noticed during the storage. Analysis of carotenoid metabolic gene expression and PSY protein level revealed a decreased expression of carotenogenic genes and PSY protein following the storage, indicating that the increased carotenoid level might not be due to increased biosynthesis. Instead, the increase likely resulted from a continuous biosynthesis with a possibly reduced turnover and/or enhanced sequestration, suggesting a complex regulation of carotenoid accumulation during fruit storage. This study provides important information to our understanding of carotenogenesis and its regulation during postharvest storage of fruits.  相似文献   

20.
B. Steinitz  H. Drumm  H. Mohr 《Planta》1976,130(1):23-31
Summary It is demonstrated that phytochrome-mediated anthocyanin synthesis in the epidermal cells of mustard seedling cotyledons takes place only 27 h after sowing onwards (at 25°C). This starting point cannot be shifted by light treatments or by nutrients. The late appearance of competence for P fr (P r and P fr, red- and far-red absorbing forms of phytochrome, respectively) with regard to anthocyanin synthesis is not related to the phytochrome system per se (P rP fr) as this is fully functional immediately after sowing of the seed; nor is it related to the primary reaction of phytochrome: P fr+XP fr XP fr X (X, X, two forms of a receptor for P fr) or to the initial action of P fr X:P fr X+KY (K, coupling element, leading to the product Y, which is no longer photoreversible). Rather, the starting point is determined by internal factors only and is thus not accessible to any specific control by external factors. On the other hand, however, the beginning of the initial action of P fr X (coupling point) can be shifted by light via phytochrome under high irradiance conditions. Moreover, it is shown that there is no phytochrome-independent effect of blue light on photomorphogenesis in the young mustard seedling and that there is no rapid dark reversion of P fr which can be detected by physiological means, at least duringAbbreviations P r red-absorbing forms of phytochrome - P fr far-red-absorbing forms of phytochrome - P 1 total spectrophotometrically detectable phytochrome - HS Hoagland's nutrient solution - HIR high irradiance response  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号