responses of pisum sativum to soil arsenate, lead and zinc - CiteSeer

84 Pages·2003·0.5 MB·English

RESPONSES OF PISUM SATIVUM TO SOIL ARSENATE, LEAD AND
ZINC: A GREENHOUSE STUDY OF MINERAL ELEMENTS, PHYTASE
ACTIVITY, ATP AND CHLOROPHYLLS
Aira E.A. Päivöke
Department of Biosciences
Division of Plant Physiology
University of Helsinki
Academic dissertation
To be presented, with the permission of the Faculty of Science of the University of
Helsinki, for public criticism in auditorium 1041 of Biocenter II, Viikinkaari 5, Helsinki,
on June 13th, 2003, at 12 o‘clock noon
Supervisor: Professor Emerita Liisa Simola
Department of Biosciences
Division of Plant Physiology
University of Helsinki
Finland
Reviewers: Professor Satu Huttunen
Department of Biology
University of Oulu
Finland
Professor Emeritus Wilfried H.O. Ernst
Department of Ecology and Physiology of Plants
Faculty of Earth and Life Science
Vrije Universiteit
Amsterdam
The Netherlands
Opponent: Professor Antti Jaakkola
Department of Applied Chemistry and Microbiology
Faculty of Agriculture and Forestry
University of Helsinki
Finland
ISSN 1239-9469
ISBN 952-10-1033-9 printed version
ISBN 952-10-1034-7 e-thesis (PDF)
Electronic version at http://ethesis.helsinki.fi
Yliopistopaino, Helsinki
Front cover: Flowering shoot of Pisum sativum cv. ‘Phenomen’.
“There´s no such place as far away” (Richard Bach)
TABLE OF CONTENTS
LIST OF ORIGINAL PUBLICATIONS 7
ABSTRACT 8
ABBREVIATIONS 10
1. INTRODUCTION 11
1.1 Wider problem context 11
1.1.1 Arsenic 11
1.1.2 Lead 11
1.1.3 Zinc 12
1.2 Pea crop 12
1.3 Peat 13
1.4 The present study 14
2. AIM OF THE STUDY 14
3. REVIEW OF THE LITERATURE 15
3.1 Sources of soil arsenic, lead and zinc 15
3.1.1 Arsenic 15
3.1.2 Lead 16
3.1.3 Zinc 17
3.2 Bioavailability of arsenic, lead and zinc 17
3.2.1 Soil pH and oxidation/reduction potential 18
3.2.2 Soil constituents 19
3.2.3 Manipulation of bioavailability 19
3.2.4 Rhizosphere 20
3.2.5 Temperature 22
3.3 Early research 22
3.3.1 Arsenic 22
3.3.2 Lead 23
3.3.3 Zinc 23
3.4 Uptake of essential and nonessential elements 23
3.4.1 Uptake of arsenate 24
3.4.2 Uptake of lead 24
3.4.3 Uptake of zinc 24
3.5 Transporters 25
3.5.1 ATPases 25
3.5.2 Cation Diffusion Family 26
3.5.3 ZIP and ZNT transporters 26
3.5.4 NRAMP 27
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3.6 Tolerance and toxicity 27
3.7 Physiological response mechanisms 28
3.7.1 Phytochelatins 28
3.7.1.1 Induction of phytochelatins by arsenate 30
3.7.1.2 Induction of phytochelatins by lead 30
3.7.1.3 Induction of phytochelatins by zinc 31
3.7.2 Organic acids 31
3.7.3 Polyphosphates 32
3.7.4 Proteins 32
3.7.5 Cell division 32
3.7.6 Cell walls 33
3.7.7 Suberization and lignification 33
3.7.8 Membrane functions 34
3.7.9 Oxidative stress 34
4. MATERIALS AND METHODS 34
4.1 Seed material and duration of cultures (I-IV) 34
4.2 Soil mixture (I-IV) 35
4.3 Artificial contamination of soil (I-IV) 35
4.4 Sowing and sequencing of cultures (I-IV) 38
4.5 Greenhouse conditions (I-IV) 38
4.6 Assessment of responses to arsenate, lead and zinc (I-IV) 38
4.6.1 Growth and development (I-IV) 38
4.6.2 In vivo and in vitro phytase activity of
cotyledons (I-III) 38
4.6.3 ATP (IV) 41
4.6.4 Chlorophyll a and b (I-IV) 42
4.6.5 Accumulation and partitioning of elements (I-III) 42
4.6.6 Element analysis (I-III) 42
4.7 Analytical accuracy (I-IV). 43
4.8 Statistical analysis (I-IV) 43
5. RESULTS AND DISCUSSION 44
5.1 Germination and remobilization from cotyledons (I-IV) 44
5.1.1 Dry matter (I-IV) 44
5.1.2 In vivo and in vitro phytase activity (I-III) 44
5.1.3 Remobilization of mineral elements (I-III) 45
5.2 ATP concentration of seedlings (IV) 46
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5.3 Growth and accumulation of arsenic, lead and zinc (I-III) 47
5.3.1 Arsenate (I) 47
5.3.2 Lead (II) 48
5.3.3 Zinc (III) 49
5.4 Chlorophyll concentrations (I-IV) 49
5.5 Concentrations and relationships of mineral
elements (I-III) 50
5.5.1 Nitrogen (I-III) 51
5.5.2 Phosphorus (I-III) 52
5.5.3 Potassium (I-III) 52
5.5.4 Calcium (I-III) 53
5.5.5 Magnesium (I-III) 53
5.5.6 Sodium (I-III) 53
5.5.7 Sulphur (I-II) 54
5.5.8 Zinc (I-III) 54
5.5.9 Iron and copper (I-III) 55
5.5.10 Manganese (I-III) 56
6. CONCLUSIONS 57
ACKNOWLEDGEMENTS 59
REFERENCES 60
APPENDIX 1 AND 2
PAPERS I-IV
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LIST OF ORIGINAL PUBLICATIONS
The following original publications form the basis of this thesis. In the text,
these papers are referred to by their Roman numerals.
I Päivöke AEA, Simola LK (2001) Arsenate toxicity to Pisum sativum:
Mineral nutrients, chlorophyll content, and phytase activity.
Ecotoxicol Environ Safety (Environ Res section B) 49: 111-121.
II Päivöke AEA (2002) Soil lead alters phytase activity and mineral
nutrient balance of Pisum sativum. Environ Exp Bot 48: 61-73.
III Päivöke AEA (2003) Mineral elements and phytase activity in
Pisum sativum grown at different Zn supply levels in the green-
house. Environ Exp Bot 49: 285-294.
IV Päivöke AEA (2003) Soil pollution alters ATP and chlorophyll con-
tents in Pisum sativum seedlings. Biol Plant 46: 145-148.
Reprinting of papers I, II and III is with kind permission of Elsevier Science.
Reprinting of paper IV is with kind permission of Kluwer Academic Publishers.
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ABSTRACT
The responses of Pisum sativum cv. ‘Phenomen’ to arsenate, Pb and Zn were examined
in potted soil cultures of 3-12 and 21 days´ duration in the greenhouse. A wide range of
soil concentrations of these elements were studied, including those considered to be ac-
ceptable for agricultural soils (2-20 mg As, 500 mg Pb and 300 mg Zn kg-1 dry soil).
Growth, remobilization of cotyledon reserves, chlorophylls, ATP and mineral elements
were assessed, with particular interest in interparameter relationships.
The effects of arsenate, Pb or Zn on the growth of seedlings contributed indirectly
to the early decline (at and after day 9) of in vivo total phytase activity of the cotyle-
dons. Element-specific impacts on the export of individual mineral elements from the
cotyledons suggested that requirements of the axis, and some mechanisms mediating
element remobilization, may have been altered.
Low levels of soil arsenate, Pb and Zn (40 µmol As, 2 mmol Pb and 5.3 mmol Zn kg-1,
respectively) increased ATP concentrations in the seedlings. The parameters of growth and
ATP concentrations correlated inversely in plants exposed to arsenate or Zn. Only Zn re-
duced the chlorophyll concentrations in seedlings, and a surplus of ATP per total chloro-
phyll concentration occurred. In adult plants, arsenate raised chlorophyll a and b concen-
trations, but their ratio declined; Pb and Zn had no impact on chlorophyll concentrations in
adult plants.
During the 21-day exposure, the shoots were usually more sensitive than the roots.
Shoot dry weight (dwt) declined even at low (24 µmol As kg-1) arsenate concentrations,
and relatively more As accumulated from lower than from higher soil As concentrations.
Under Pb exposure, the soil Pb concentration reducing shoot yield by 10% was lower
(1.4 mmol Pb kg-1) than the concentration for 90% (3.5 mmol Pb kg-1) root tolerance in-
dex (TI), but the dwt-based TI responded in an inversely linear manner to soil Pb concen-
tration. Medium (6.5 mmol) soil Pb concentration yielded higher plant Pb concentration
and total content than low (1.1 mmol) or high (9.4 mmol Pb kg-1) soil concentrations.
Shoot dwt declined at or higher than 3.2 mmol Zn kg-1 dry soil, but the decline stagnat-
ed when soil Zn level rose. The fraction (%) of shoot Zn correlated inversely with soil Zn
concentration.
Arsenate, Pb and Zn all caused an increase in plant Mg concentration. The tops of
Pb- and Zn-exposed plants had higher Mg concentrations than the average levels found
in the shoots, while in arsenate-exposed plants the fraction occurring in the roots rose.
Pb and Zn reduced P concentrations in the roots and arsenate those of the shoots. Pb
lowered the root, and Zn the shoot N concentrations, but the decline stagnated. The
shoot K concentration correlated inversely with soil Pb. In Zn-exposed plants, shoot Fe
concentration and total Fe content of the entire plants declined.
Parallel change relationships between a number of elements occurred in plants
grown with arsenate, Pb and Zn, pointing to some response mechanisms of P. sativum
that might be shared by these three elements. The parallel change and correlations sug-
gested that, apart from Mg, Ca and K also played significant roles under Pb and Zn ex-
posure. The results also suggested that the roles played by Mn and Na could have been
altered under exposure to arsenate, Pb and Zn.
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Significant responses in P. sativum cv. ‘Phenomen’ occurred even at or below the
maximum allowed soil concentrations of these three elements in agricultural soils. Re-
sults confirmed the necessity to consider species- and element-specific toxicity safety
ranges, and that low soil concentrations may be even more harmful than higher con-
centrations. It is concluded that the observed trends and directions of change are rele-
vant and should also be focused on in the field.
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ABBREVIATIONS
ATP Adenosine triphosphate
EC Effective concentration to lower yield by 10%
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FAO Food and Agricultural Organization of the United Nations
HELCOM Helsinki Commission – Baltic Marine Environment
Protection Commission
NADPH Nicotinamide adenine dinucleotide phosphate (reduced)
OECD Organization for Economic Cooperation and Development
PAL Phenylalanine ammonia-lyase
TI Tolerance index
WHO World Health Organization
Other abbreviations are used only in sections in which they are explained.
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