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Plant Sulfur Research

Fundamental, Agronomical and Environmental Aspects
of Sulfur Nutrition and Assimilation in Plants


Karl

I found this reference yesterday while searching information on cellular issues

http://www.plantsulfur.org/reports/sia29.htm

What is apparent to me that none of the sites I have found understand where organic sulfur originates. Some say that the phytoplankton make it others say it come from the clouds while no one seems to understand that the sulfur cycle is all about
heat and especially the heat of the magma from the center of the earth.
Mineral sulfur is created when volcanic activity occurs in the atmosphere while organic sulfur upon which the plankton feed occurs when this same volcanic activity occurs in sea water. The salt enables the sulfur to become free molecules
within the sea, replaced or released by the sodium. Organic chemistry can best be observed in the oceans that surround us.

In the second paragraph of the article "air pollutants SO2 and H2S MAY also be used
directly as a sulfur source by the leaves." The discussion of acid rain makes this statement ludicrous, but it shows how chemists fail to understand the ability of sulfur to bond with almost every other element and in turn become unavailable biologically.
Sulfur is taken up by the roots not the leaves just as sulfur is absorbed via the gastrointestinal system as opposed to topically.

The value of the article attached is regarding glutathione, whether in plants or animals sulfur is necessary for the production of this vital amino acid. When we depend on man's chemistry to copy what God hath made the results seem to be incomplete.

Patrick

______________________________________________

The role of glutathione in the development of stress and damage to plants

Source

Michael Tausz, Astrid Wonisch, Maria Müller and Dieter Grill

 

Institute of Plant Physiology, University of Graz, Schubertstraße 51, A-8010 Graz, Austria

 

Besides its role as a central compound in the sulfur metabolism, glutathione is a major component of the cellular antioxidative defense system [7]. Although its direct affinity towards oxidizing free radicals is supposed to be rather low under physiological conditions [8], it is necessary for the regeneration of ascorbate and the protection of protein thiols. In this overview some representative excerpts on the current research at the Institute of Plant Physiology, University of Graz, regarding sulfur metabolism and the role of glutathione conducted, is presented.

            The phytotoxic air pollutants SO2 and H2S may also be used directly as sulfur source by the leaves. The reduced sulfur of H2S is incorporated directly into cysteine and further glutathione, whereas SO2 is reduced by the sulfur assimilation pathway in an energy consuming process [1,2]. Thus, both agents lead to increased levels of reduced sulfur in the leaves, mainly in the form of glutathione [1, 3]. Although there are a lot of studies dealing with these effects in herbaceous plants and some on shoots of trees, only few investigations were aimed at the roots of trees [13]. In young spruce trees, only fumigation of H2S (225 nl l-1 for three weeks) lead to a significant increase in glutathione content of the roots, but not a fumigation with the same dose of SO2 (Fig. 1).

            This increase might be due to the basipetal transport of glutathione excessively synthesized in the needles. Alternatively, glutathione formation might take place in the roots and translocation to the shoots might be inhibited due to the lack of demand. The results of Rennenberg and Herschbach [9] support the latter hypothesis, since basipetal phloem transport was found in beech, but not in spruce trees. The time scale of glutathione changes in roots of spruce trees is two to three weeks compared to days in needles or in herbaceous plants (Wonisch et al., [14]). The contribution of glutathione changes in the roots to damages and growth reductions remains unclear.

            In green plant tissues, the glutathione pool is largely kept in the reduced state. Oxidized glutathione (GSSG) accounts for between 5 and 15% of total [8]. Under oxidizing conditions the proportion of GSSG may be increased. Such an increase was observed on damaged spruce needles in the field [11]. In a study on ozone injury to Pinus ponderosa in the San Bernardino Mountains in Southern California a higher proportion of GSSG could be found in sun exposed needles of sensitive individuals (Fig. 3). This change was measurable before any visible symptoms occurred on the needles. Furthermore, it was still reversible upon dark adaptation of these needles. However, since resistant individuals growing at the same plot and thus experiencing the same ozone dose did not show this redox changes, it might be concluded that oxidation of glutathione is an initial indicator of biochemical damage within the cells rather than a direct consequence of ozone oxidation potency. At the time of these investigations, the ascorbate and tocopherol systems were still largely uninfluenced.             Among many other substances, sulfurous air pollutants induce chromosomal damages (counted as percentage aberrations in ana- and metaphases) in meristems of spruce trees.

Figure 1. Total GSH contents in fine roots (< 2 mm diameter, dw = dry weight) of three years old Picea omorika trees treated in fumigation cabinets. Open symbols = control, closed symbols = fumigated variant. Asterisks mark significant differences between fumigated variant (closed symbols) and control (open symbols). Decision rule: p<0.05, Mann-Whitney-test. Data adapted from Wonisch et al. [14].

 

Figure 2. Percentage of GSSG in total GSH in current (A) and previous year’s needles (B) of ozone sensitive and resistant Pinus ponderosa trees grown at the same plot in the San Bernardino Mountains, CA, US. Light exposed: samples are taken at midday in full sun, dark exposed samples were allowed to dark adapt overnight. Asterisks mark significant differences between light and dark adapted samples (p<0.05, Wilcoxon test, n=5). Data adapted from Tausz et al. [12].

 

Fumigation experiments with SO2 [6] and H2S (14) revealed an increased number of chromosomal aberrations in dividing root tip cells of spruce trees. The signaling pathway of the impact of air pollutants on the canopy leading to chromosomal abnormalities in the roots is still enigmatic. Recently, experimental studies on young spruce seedlings showed that glutathione is able to induce increased rates of chromosomal damages after external application to the roots. Concentrations of  50-500 µmol l-1 glutathione induced a significant increase over control depending on treatment duration (Müller et al. [4]). Simultaneously, the mitotic index, a measure of mitotic activity, was decreased (Table 1). If this pathway is of importance under more natural conditions remains to be elucidated.

 

Table 1. Effects of 12 h glutathione treatment (externally applied in distilled water) on chromosomal aberrations and mitotic indices in root tips of 12 days old spruce seedlings. Medians (20-80 percentile ranges) of 6 samples per variant. Different letters indicate significant differences at p<0.05. Data adapted from Müller et al. [4].

 

 

Glutathione concentration [mM]

 

0

0.05

0.1

0.5

 

Mitotic index [%]

9.2 (2.9)a

9.4 (0.8)a

2.6 (1.2)b

6.4 (1.1)c

 

Aberrations [%]

4.4 (1.0)a

9.6 (1.4)b

12.5 (2.8)c

8.6 (2.0)b

 

 

            The cellular and intracellular distribution of glutathione may be of importance for effects on the antioxidative system and on the nucleus. The use of the specific fluorescent dyes monochlorobimane or mercury-orange allows a specific in vivo staining of thiol groups in cells. The adaptation of methods developed on animal cells to plant cells proved successful on certain plant materials (epidermal cells of Allium cepa) and a quantification of the staining intensity was possible by the help of digital image analysis (Müller et al. [5]. Recently, an adaptation of the monochlorobimane method was described for Arabidopsis roots [10]. However, in our experiments with spruce and Allium roots, a very strong unspecific fluorescence at the emission wavelength of bimane prevented a successful application of this histochemical method so far.

 

Acknowledgments

This work is financially supported by the‚ Fonds zur Förderung der wissenschaftlichen Forschung (FWF), Project P11836 BIO‘ and included in the COST Action 829. Additional support by the Dutch (NUFFIC) and Austrian Government (Federal Ministry of Science and Traffic) is gratefully acknowledged.

 

References

  1. 1.     De Kok L.J., Stuiver C.E.E. and Stulen I. 1998. Impact of atmospheric H2S on plants. – In: De Kok L.J. & Stulen I. (eds.), Responses of plant metabolism to air pollution and global change, 51-63. , – Backhuyes Publishers, Leiden, The Netherlands.
  2. 2.     De Kok L.J. 1990. Sulfur metabolism in plants exposed to atmospheric sulfur. In: Rennenberg H., Brunold C., De Kok L.J. and Stulen I. (eds.) Sulfur nutrition and sulfur assimilation in higher plants. Fundamental, environmental and agricultural aspects, pp. 111-130, SPB Academic Publishing, The Hague.
  3. 3.     Grill D., Esterbauer H. and Hellig K. 1982. Further studies on the effect of SO2-pollution on the sulfhydryl-systems of plants. - Phytopath. Z. 104: 264-271.
  4. 4.     Müller M., Tausz M. and Grill D. Effects of exogenous glutathione on root tip chromosomes of spruce trees – Does it exert mutagenic effects (in preparation a).
  5. 5.     Müller M., Tausz, M., Guttenberger H. and Grill D. 1999. Histochemical localization of glutathione in plant tissues: A comparison of two fluorescence staining methods. (in preparation b).
  6. 6.     Müller M., Zellnig G., Tausz M., De Kok L. J. and Grill D. 1998. Root responses of forest trees to environmental stresses. In: L. J. De Kok and I. Stulen (eds.) Responses of plant metabolism to air pollution, pp. 383-386, Backhuys Publishers, Leiden.
  7. 7.     Noctor, G., Arisi, A. M., Jouanin, L., Kunert, K. J., Rennenberg, H. and Foyer, C. H. 1998. Glutathione: biosynthesis, metabolism and relationship to stress tolerance explored in transformed plants. J. Exp. Bot. 49, 623-647.
  8. 8.     Polle, A. and Rennenberg, H. 1994. Photooxidative stress in trees. In: C. H. Foyer and P. M. Mullineaux (eds), Causes of photooxidative stress and amelioration of defense systems in plants, pp. 199-218. CRC Press, Boca Raton.
  9. 9.     Rennenberg H. and Herschbach C. 1995. Sulfur nutrition of trees: A comparison of spruce (Picea abies L.) and beech (Fagus sylvatica L.). J. Plant Nutri. Soil Sci. 158: 513-517.
  10. 10.  Sánchez-Fernández R, Fricker M., Corben L.B., White N.S., Sheard N., Leaver C.J., Van Montagu M., Inze D., . and May M.J. 1997. Cell proliferation and hair tip growth in the Arabidopsis root are under mechanistically different forms of redox control. Proc. Natl. Acad. Sci USA 94, 1745-2750.
  11. 11.  Schmieden U., Schneider S. and Wild A. 1993. Glutathione status and glutathione reductase activity in spruce needles of healthy and damaged spruce trees at two mountain sites. Environ. Poll. 82: 239-244.
  12. 12.  Tausz M., Bytnerowicz A., Weidner W., Arbaugh M. J., Padgett P. and Grill D. 1999. Stress-physiological variables describe the susceptibility of Pinus ponderosa to ozone in Southern Californian forests (in preparation).
  13. 13.  Tausz M., Van der Kooij T. A. W., Müller M., De Kok L. J. and and Grill D. 1998. Uptake and metabolism of oxidized and reduced sulfur pollutants by spruce trees. In: L. J. De Kok and I. Stulen (eds.) Responses of plant metabolism to air pollution, pp. 455-458, Backhuys Publishers, Leiden, . pp. 455-458.
  14. 14.  Wonisch A., Tausz M., Müller M., Weidner W., De Kok L. J. and Grill D. 1999. The time dependent changes of thiols and chromosomal aberrations in roots of young spruce trees exposed to SO2 and H2S. (in preparation).

 

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