The Effect of Light on Carotenoids of Etiolated Mung Bean Seedlings

Etiolated mung bean seedlings have been shown to contain thefollowing carotenoids: phytofluene, ß-carotene, ß-zeacarotene,5,6-monoepoxy-ß-carotene, 5,6:5', 6'-diepoxy-ß-carotene,violaxanthin, lutein, 5,6-monoepoxylutein, flavoxanthin, andauroxanthin whereas in the light -carotene and neoxanthin werealso identified. In the dark, total carotenoids after 8 dayswere 71.4 µg/g compared to 926.5 µg/g dry weightin light. In the dark, whereas most of the other individualcarotenoids were decreasing between 6 and 8 days, auroxanthinwas increasing. Further, flavoxanthin (5,8-monoepoxylutein)and auroxanthin (5,8:5', 8'-diepoxyzeaxanthin) were decreasingand disappeared in the light. Total xanthophylls increased much more than total caroteneson illuminating etiolated seedlings; lutein increased much morethan ß-carotene. This is in agreement with Goodwinand Phagpolngarm's (1960) results and in contrast to those ofother workers who suggested that ß-carotene was rapidlysynthesized whereas xanthophyll levels altered only slightlyunder these conditions. However, a critical look at these resultsshowed that a considerable increase in carotenes was more thanmatched by the increase in xanthophylls.     

Development of the Primary Photochemical Apparatus of Photosynthesis during Greening of Etiolated Bean Leaves

Seven-day-old dark-grown bean leaves were greened under continuous light. The amount of chlorophyll, the ratio of chlorophyll a to chlorophyll b, the O₂ evolving capacity and the primary photochemical activities of Photosystem I and Photosystem II were measured on the leaves after various times of greening. The primary photochemical activities were measured as the photo-oxidation of P₇₀₀, the photoreduction of C-550, and the photo-oxidation of cytochrome b₅₅₉ in intact leaves frozen to −196 C. The results indicate that the reaction centers of Photosystem I and Photosystem II begin to appear within the first few minutes and that Photosystem II reaction centers accumulate more rapidly than Photosystem I reaction centers during the first few hours of greening. The very early appearances of the primary photochemical activity of Photosystem II was also confirmed by light-induced fluorescence yield measurements at −196 C.     

Chlorophyll Formation in Greening Bean Leaves during the Early Stages

In the evolution of the absorption spectrum of etiolated bean leaves (Phaseolus vulgaris L.) following illumination, a rapid photoconversion of 50% or more of the active protochlorophyllide at room temperature is followed by a shift of the chlorophyll(ide) absorption maximum: C₆₇₈→ →C₆₈₄→C_{672 nm}. Kinetic studies at 2 C and the absence of an isosbestic point provide evidence for an intermediate between C₆₇₈ and C₆₈₄. A dramatically different evolution is observed following the photoconversion of only 5 to 30% of the active protochlorophyllide at room temperature. C₆₇₂ appears within 30 seconds, and no subsequent dark shift occurs during the following 90 minutes. At 0 C, conversion of 5% of the active protochlorophyllide produces a new species, C₆₇₆, which converts progressively to C₆₇₂ within 10 minutes. We interpret the results in terms of two photochemical steps operating in series for the complete conversion of active protochlorophyllide. Furthermore, there appears to be competition between an irreversible, terminal dark shift and the second light reaction. We propose a scheme based on dimers of protochlorophyllide reduced stepwise to dimers of chlorophyllide in two successive light reactions. The intermediate mixed protochlorophyllide-chlorophyllide dimer absorbs at 676 nm and displays a much faster dissociation to monomers than does the chlorophyllide-chlorophyllide dimer.     

The Effect of Age on the Phytochrome-Mediated Chlorophyll Formation in Dark-grown Bean Leaves

The effect of red and far-red treatment on chlorophyll synthesis in dark-grown bean leaves was studied at various ages. Although the effect was pronounced in the old leaves, no effect was observed in the young ones (4 days old). In the 5-day old leaves a measurable effect of red light pretreatment can be observed, whereas the far-red reversal effect was not observed. — The length of the dark period between the red pretreatment and the continuous illumination is also age dependent. Leaves older than 6 days show a maximum at about six hours, while in the young leaves the red light effect increases with the time of dark incubation up to the 24 hours tested. — The reversal effect of far-red light on protochlorophyllide regeneration was also examined. The far-red light has no reversal effect on leaves younger than 6 days old, while on the old leaves it has such an effect.     

光质对绿豆幼苗叶片超微弱发光及叶绿素含量的影响

以绿豆幼苗为试材,测定其叶片超弱发光(UBE)及叶绿素含量在不同光质条件下的变化,并探讨两者之间的关系.结果表明,生长在不同光质下绿豆幼苗叶片的UBE及延迟发光衰减参数1/P都随着其生长不断增强,且生长在白光下绿豆幼苗的UBE是生长在其他光质(红、黄、蓝、绿)下幼苗的2倍以上,而红光、黄光和绿光处理之间无显著差异;生长在白光下的绿豆幼苗叶片叶绿素含量显著高于红、黄、蓝、绿光处理幼苗,而红光和黄光处理又显著高于蓝光和绿光处理.研究发现,光质对绿豆幼苗叶片超弱发光和叶绿素含量影响相似,绿豆幼苗叶片超弱发光可能与叶绿体的发育和光合作用有关.     

Purification of a Soluble Cytockinin-binding Protein from Etiolated Mung Bean Seedlings

A cytokinin-binding protein (CBP) was purified from a crude extract of etiolated mung bean seedlings by a protocol involving affinity chromatography on benzyladenine-linked Sepharose 4B, ion exchange chromatography on DEAE-Sephadex A50, and gel filtration on Sphacryl S-400. The molecular weight was estimatd to be about 200,000 by gel filtration. CBP appeared as two bands corresponding to molecular weights of about 45,000 and 48,000 on SDS-polyacrylamide gel electrophoresis. The dissociation constant for benzyladenine was 7.5 x 10^-7 M. ¹⁴C-Benzyladenine-binding to CBP was reversible and could be inhibited by the addition of kinetin or trans-zeatin. Adenine, AMP, and ADP had no inhibitory effect on the binding of ¹⁴C-benzyladenine to CBP but the addition of ATP to the assay mixture enhanced the binding.     

The Mode of Action of Organdie-Damaging Factor from Mung Bean Leaves

Organelle-damaging factor, which damages cell organelles andcauses them to release their matrix enzymes at pH 7.5, had noability to actively hydrolyze carbohydrates, proteins and lipidsat pH 7.5. When the factor was incubated with spinach chloroplastsin the presence of calcium ions, the matrix enzyme, triosephosphateisomerase, was released from chloroplasts after a lag period.A significant amount of activity of the factor was lost duringthe release. We suggest that the factor is not an enzyme andbounds tightly to organelle membranes to break them. (Received October 6, 1980; Accepted December 3, 1980)     

High-Pressure Effects on Vacuolar H+-ATPase from Etiolated Mung Bean Seedlings

A high-hydrostatic-pressure technique was employed to study the structure-function relationship of plant vacuolar H⁺-ATPase from etiolated mung bean seedlings (Vigna radiata L.). When isolated vacuolar H⁺-ATPase was subjected to hydrostatic pressure, the activity of ATP hydrolysis was markedly inhibited in a time-, protein concentration- and pressure-dependent manner. The pressure treatment decreased both V _max and K _m of solubilized vacuolar H⁺-ATPase, implying an increase in ATP binding affinity, but a decrease in the ATP hydrolysis activity. Physiological substrate, Mg²⁺-ATP, augmented the loss of enzymatic activity upon pressure treatment. However, ADP, AMP, and Pi exerted substantial protective effects against pressurization. Steady-state ATP hydrolysis was more sensitive to pressurization than single-site ATPase activity. The inactivation of solubilized vacuolar H⁺-ATPase by pressure may result from changes in protein–protein interaction. The conformational change of solubilized vacuolar H⁺-ATPase induced by hydrostatic pressure was further determined by spectroscopic techniques. The inhibition of vacuolar H⁺-ATPase under pressurization involved at least two steps. Taken together, our work indicates that subunit–subunit interaction is crucial for the integrity and the function of plant vacuolar H⁺-ATPase. It is also suggested that the assembly of the vacuolar H⁺-ATPase complex is probably not random, but follows a sequestered pathway.     

Characterization of 2,4-D Binding to the Auxin-binding Protein Purified from Etiolated Mung Bean Seedlings

New acetylenic nematicidal compound, penipratynolene (1), methy (2′R)-4-(2′-hydroxy-3′-butynoxy)benzoate, together with two known compounds, 6-methoxycarbonylpicolinic acid (2) and 2,6-pyridinedicarboxylic acid (3), were isolated from the culture filtrate of Penicillium bilaiae Chalabuda. The structures of 1–3 were established by spectroscopic methods. The absolute configuration of 1 was confirmed by using a modified version of Mosher’s method. Compounds 1–3 showed nematicidal activity of 77%, 52%, and 98%, respectively, by a bioassay at 300 mg/l with the root-lesion nematode Pratylenchus penetrans.     

Auxin-Binding Protein in Etiolated Mung Bean Seedlings: Purification and Properties of Auxin-Bindmg Protein-II

An auxin-binding protein (ABP-II) was purified from the extractof etiolated mung bean seedlings by affinity chromatographyon 2,4-D-linked Sepharose 4B and by gel filtration on Sepharose4B and Sephacryl S-200. The molecular weight was estimated tobe about 190,000 by gel filtration on Sephacryl S-200. ABP-IIgave a single band corresponding to a molecular weight of about48,000 on SDS-polyacrylamide gel electrophoresis. The dissociationconstants of ABP-II for 2,4-D determined by amrnonium sulfateprecipitation and equilibrium dialysis were 9.5?10^–6 Mand 1.1?10^–5 M, respectively. ¹⁴C-2,4-D-binding to ABP-IIwas reversible and inhibited by addition of IAA, naphthalene-1-aceticacid, 2,4,5-trichlorophenoxyacetic acid or p-chlorophenoxyisobutylicacid to the assay mixture. (Received September 5, 1984; Accepted November 5, 1984)     

Purification of an Auxin-Binding Protein from Etiolated Mung Bean Seedlings by Affinity Chromatography

An auxin-binding protein with high affinity for 2,4-D and IAAwas purified from the extract of etiolated mung bean seedlingsby affinity chromatography on 2,4-D-linked Sepharose 4B andby gel nitration on Sepharose 4B. Its molecular weight was estimatedto be about 390,000 by gel nitration on Sepharose 4B and itconsisted of two different subunits with molecular weights ofabout 47,000 and 15,000. This protein had no ribulose-l,5-bisphosphatecarboxylase activity. Its dissociation constants for 2,4-D andIAA were 9.3 x 10^–6 M and 3.2 x 10^–6 M, respectively,as determined by Scatchard's method. (Received December 21, 1982; Accepted March 23, 1983)     

Effects of Uniconazole on Leaves Photosynthesis,Root Distribution and Yield of Mung Bean (Vigna radiata)

Journal of Plant Growth Regulation - Uniconazole was a plant growth retardant with effect of regulating plant growth and development, however, there were very few studies on its application to mung...     

Regulation of Phytochrome on Swelling of Protoplasts Isolated from Hypocotyl of Etiolated Mung Bean Seedlings

Protoplasts from hypocotyls of etiolated mung bean (Phaseolus raditus L. ) seedlings were maintained at a constant osmotic potential at 20±2℃, and they were found to swell gradually after being pulsed with red light (R) (10.5 W · m-2, 3 min) when CaCl2 was present in the medium. The volume reached maximum during 30--60 min after R-irradiation and decreased swelling afterwards. Farred light (FR) irradiation in presence or absence of Ca2+ did not influence the protoplast volume. The R-effect was photoreversible by subse- quent FR (2.5 W · m-2, 5 min) irradiation, usually seen over two R-FR cycles. Furthermore, swelling response was in positivecorrelation with red light intensity and duration of R pulse, indicating the involvement of phytoehrome. FR became less effective in reversing the effect of R after 10 min in dark between R and FR. Protoplast swelling occurred only when Ca2+ ions (1 mmol/L) then Ca2+ ions (1 mmol/L) is added to the medium 5 rain after R. The effect of Ca2+ could not be replaced by Mg2+, Ba2+, Zn2+, or K+. The time course of water (3H20) uptake into protoplasts after R-irradiation was consistent with the trend of protoplast swelling, indicating the existence of certain relationship between the swelling and water uptake of the protoplasts.