Penetration of blue nad UV radiation measured by fiber optics in spruce and fir needlesBornman, Janet F.; Vogelmann, Thomas C.
doi: 10.1111/j.1399-3054.1988.tb06368.xpmid: N/A
The penetration of blue light (460 nm) and UV‐A (360 nm) radiation into needles of spruce (Picea engelmannii Parry ex. Engelm.) and fir [Abies lasiocarpa (Hook.) Nutt. var. Iasiocrpa] was examined. The distribution of collimated and scattered light in intact needles was measured by quartz fiber optic microprobes. Both blue light and UV‐A were attenuated more rapidly with depth in fir than in spruce, although the light profiles for the two light regimes were different; blue light penetrated to a greater depth than UV‐A, Removal of the epicuticular wax from the needle surface increased the amount of internal blue light slightly, but had little effect on the amount of UV‐A. The differences in light penetration in light penetration in spruce and fir may be caused bhy different pigmentation and leaf anatomy.
Fiber optic studies of light gradients and spectral regime within Lactuca sativa achenesWidell, Karl Olof; Vogelmann, Thomas C.
doi: 10.1111/j.1399-3054.1988.tb06369.xpmid: N/A
Light gradients and spectral regime were measured in Lactuca sativa L. cv. Grand Rapids achenes using fiber optic microsensors. The distribution of scattered light across lettuce achenes was linear for 660 and 730 nm and non‐linear for 450 nm light. Spectra for scattered light within intact achenes also showed a non‐linear increase with wavelength. The preferential attenuation of blue light by the pericarp and seed explains in part the relative ineffectiveness of blue light with respect to red in triggering germination of lettuce. Calculated action spectra for phytochrome‐stimulated germination agree closely in the red with experimentally derived action spectra; however, there is little agreement within the blue.
Iron‐deficiency in pea leaves: Effect on lipid composition and synthesisAbadia, A.; Ambard‐Bretteville, F.; Remy, R.; Trémolièes, A.
doi: 10.1111/j.1399-3054.1988.tb06370.xpmid: N/A
The lipid composition of chlorotic leaves of Pisum sativum L. cv. Kelvedon Wonder, developed under iron‐deficiency was determined and compared to similar material developed under normal nutrient conditions. All lipid classes were affected by iron‐deficiency but to different extents, and thylakoid lipids were more affected than non‐thylakoid lipids. The most striking results concerned changes in the fatty acid content of the main polar lipids. The linolenic acid of the galactolipids decreased to the benefit of more saturated fatty acids, mainly linoleic acid. In phosphatidylglycerol, the proportion of Δ3‐trans‐hexadecenoic acid decreased. Using radioactive acetate, lipid synthesis was investigated. Desaturation leading to linoleic acid was less affected by iron‐deficiency than desaturation leading to Δ3‐trans‐hexadecenoic and linolenic acids.
Properties of reformed prolamellar bodies from illuminated and redarkened etiolated wheat plantsMinkov, Ivan N.; Ryberg, Margareta; Sundqvist, Christer
doi: 10.1111/j.1399-3054.1988.tb06372.xpmid: N/A
Prolamellar bodies were isolated from etiolated leaves of wheat (Triticum aestivum L. cv. Walde, Weibull), which were illuminated for 4 h and then grown in darkness for 16 h. The inner etiochloroplast membranes were isolated by differential centrifugation, and prolamellar bodies and thylakoids were separated on a 10–50% continuous sucrose density gradient. The reformed prolamellar bodies contained phototransformable protochlorophyllide as the main pigment as shown by low temperature fluorescence spectra and high performance liquid chromatography. After illumination with 3 flashes of white light almost all of the protochlorophyllide was transformed to chlorophyllide. In the thylakoids, however, most of the protochlorophyllide was not phototransformed. The reformed prolamellar bodies and the thylakoids showed a fluorescence emission ratio 657/633 nm of 5.6 and 0.5, respectively. Both membrane systems contained also chlorophyllide and chlorophyll synthesized during the illumination. Polyacrylamide gel electrophoresis showed the main chlorophyllide oxidoreductasse.
Mineral and lipid composition of Glycine ‐ Glomus ‐ Bradyrhizobium symbiosesPacoysky, Raymond S.; Fuller, Glenn
doi: 10.1111/j.1399-3054.1988.tb06373.xpmid: N/A
Soybean [Glyeine max (L.) Merr. cv. Amsoy 71] plants were inoculated with either the vesicular‐arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum. with a strain of Bradyrizobobium Japonicum. or with both endophytes in combintion. Noninoculated controlplantes were fertilized with levels of N and P previously found to compensate for nutrient input following infection by Bradyhizobium or Glomus Temporal differences in N and P assimilation in nodulated or mycorrhizal plants indicated that Glomus was most effective during early vegetative growth and Bradyrhizobion was active until the mid‐pod‐fill stage in soybean. In general. soybeans colonized by Glomus contained more Cu but less Mn and P than corresponding P‐fertilized plants. Soyubean roots infected with G. fasciculaum contained five unusual fatty acids: [16: 1 (11c): 8:3 (6c, 9c, 12c): 20:3 (8c, 11c, 14c): 20:4 (5c, 8c, 11c, 14c): 20:5 (5c, 8c, 11c, 14c, 17c)] that were absent in non‐infected roots. Fatty acid 16:1 (11c) comprised 43% of total fatty acids in Glomus‐infected roots at week 9 and 29% of total root fatty acids at week 15. This isomer of hexadecenoic acid was positively correlated with vesicle number (r = 0.92**). and 16:1 (11c) was probably the principalstorage fatty acid in fungal vesicles. These five unusual fatty acids were not found in the leaves. pods or seeds of either VAM or non‐VAM plants. Specific leaf area increased with time in nodulated soybeans. but these plants contained lessCu than corresponding N‐fertilized plants. Soybeans nodulated with Bradyrthizobium contained more total lipid and proportionately more fatty acid 16:0 than N‐fertilized plants. Infection by Glomus or Bradyrhizobium also altered the fatty acid composition of above‐ground plant parts, although these changes were subtle compared to the markedly different fatty acid found in Glomus‐infected roots. These findings suggest that seed quality may be altered due to the physiological changes resulting from infection by N2‐fixing bacteria and/or endomycorrhizal fungi. Observed differences in the plant nutrition of inoculated soybeans could not be replicated by fertilizer addition alone.
Ca2+‐dependent in vitro phosphorylation of soluble proteins from germinating wheat (Triticum turgidum) endospermKrishnan, Hari B.; Pueppke, Steven G.
doi: 10.1111/j.1399-3054.1988.tb06374.xpmid: N/A
A 40000 g supernatant fraction from extracts of germinating wheat (Triticum turgidum Desf. cv. Edmore) endosperm contains protein kinase activity that phosphorylates several endogenous proteins. In vitro incorporation of radiolabel from [32P]‐ATP into phosphoproteins was maximal in the presence of 1 mM CaCl2 and 5 mM MgCl2Ca2+ at micromolar concentrations greatly stimulated the phosphorylation of 49 and 47 kDa polypeptides and also inhibited the phosphorylation of a few specific polypeptides. The phosphorylation of the 49 and 47 kDa polypeptides was present at 2 days after seed germination and was maximal at 8 days. Quantitative protein changes were also detected during the seed germination, but differences could not be correlated with changes in protein phosphorylation. Phosphoamino acid analysis by two dimensional thin‐layer electrophoresis showed that the Ca2+‐dependent protein kinase phosphorylates a serine residue of the 47 kDa polypeptide. Ca2+‐dependent protein kinase phosphorylates a serine residue of the 47 KDa polypeptide. Ca2+ dependent protein phosphorylktion was inhibited by phenothiazine‐derived drugs. Addition of S‐adenosylmethionine to the in vitro phosphorylation reaction specifically inhibited the Ca2+‐dependent protein phosphorylation.
Nitrate and hydrogen peroxide metabolism in Medicago sativa nodules and possible effect on leghaemoglobin functionBecana, M.; Aparicio‐Tejo, P.; Sánchez‐Diaz, M.
doi: 10.1111/j.1399-3054.1988.tb06375.xpmid: N/A
The effect of NO3 (0–20 mM for 7 days) upon NO3 and H2O2 metabolism in lucerne (medicago sativa L. ev. Aragón) nodules initiated by Rhizobium meliloti strain 102F51 has been examines. Ty;pical nitrate reductase, (NR) activities of bacteroids (EC 1.7.99.4) and cytosol (EC 1.6.6.1) of nodules not treated with NO3 were 60 and 45 nmol NO2 formed (mg protein)1h−1 respectively, Inductin of bacteroid NR took place in nodules exposed ot concentrations above 5 mM No3 whereas cytosol NR was induced at 5 mM No3 decreasint at greater NO3 concentrations. In resonse to NO3 additin, NO2 increasingly accumulated in the nodule cytosol at quantities commensurate with those needed to oxidise leghaemoglobin (Lb) in vitro. A comparison of patterns of NO2 accumulation and activities of NRs expressed on a nodule weight basis indicates that plant NR contributes decisively to NO2 production at the earlier phass of nodule senescence (5–10mM No3 while bacteroid NR becomes increasingly important in generating NO2 at nore advanced stages (10–20mM NO3). Specific superoxide dismutase (SOD; EC 1.15.1.1) and catalase (EC 1.11.1.6) activities of bacteroids remained constant during the NO3 induced senescence of nodules whereas SOD activity of cytosol increased 1.5‐fold and catalase activity ws inhibited by 20% at 20 mM NO3 substantial peroxidase (EC 1.11.1.7) activity was found in the plant but none in the bacteroid fraction of nodules. Peroxidase activity increased significantly only at 20 mM NO3 concomitantly with malondialdephyde content. concentrations. Free H2O2 interferes wihjt Lb function in vivo is suggested.
The effects of nitrate on the enzymes involved in nitrogen assimilation in nodulated pea rootsVézina, L.‐P.; Joy, K. W.; Hope, H. J.
doi: 10.1111/j.1399-3054.1988.tb06376.xpmid: N/A
Pea Plants (Pisum sativaum L. ev. Little Marvel) were grown in N‐free medium and when well nodulated (28 days) were supplied for 8 days with nitrate or ammonium. Over the 8 days of nitrate treatment, total amino and amide N in sap declined, and the proportion of aspartate relative to the other amino acids increased. After 8 days of treatment, nitrogenase (EC 1.18.2.1) activity in nitrate‐treated plants declined to about 30% of the activity in controls even though nodules were not directly in contact with nutrient solution. Nitrogenase activity was also decreased by the addition of ammonium chloride (10 mM). With addition of nitrate or ammonium. clear signs of senescence began to show in the nodules after 4 days. Nitrate reductase (EC 1.6.6.1) activity was induced in roots by nitrate, but decreased sharply in nodules. In response to nitrate addition, newly formed root tissues showed 3‐ to 5‐times higher glutamine synthetase (GS. EC 6.3.1.4) activity than newly formed tissues of control plants, expressed on a protein or weight basis. In complementary experiments, when ammonium salts were used instead of nitrates, the increase in GS activity was significantly lower. GS activity decreased in nodules of treated plants and total extractable protein was 3 times lower in nodules of nitrate‐treated plants than in controls at day 8 of treatment.