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The interaction between aluminium toxicity and drought stress in common bean (Phaseolus vulgaris L.) [Elektronische Ressource] : physiological and molecular aspects / Zhongbao Yang

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The Interaction between Aluminium Toxicity and Drought Stress in Common Bean (Phaseolus vulgaris L.) Physiological and Molecular Aspects Von der Naturwissenschaftlichen Fakultä t der Gottfried Wilhelm Leibniz Universitä t Hannover zur Erlangung des Grades Doktor der Naturwissenschaften Dr. rer. nat. genehmigte Dissertation von Master of Agriculture Zhongbao Yang geboren am 28.11.1979 in Tancheng, VR China 2011 Referent: Prof. Dr. rer. agr. Walter J. Horst Gottfried Wilhelm Leibniz Universitä t Hannover Korreferent: Prof. Dr. rer. nat. Hans-Peter Braun Gottfried Wilhelm Leibniz Universitä t Hannover Tag der Promotion: 07.Juli 2011 ABSTRACT Aluminium (Al) toxicity and drought are two major abiotic stress factors limiting common bean (Phaseolus vulgaris L.) production in the tropics. The Al-impeded root growth may strongly limit the water exploitation of roots from subsoil and thus less ability to withstand drought stress in the acid soils. In light of the importance of root development under Al toxicity and drought stress, in this study the short-term effects of combined Al toxicity and drought stress on root growth with special emphasis on physiological and molecular mechanisms in the root apex was investigated.

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Published 01 January 2011
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The Interaction between Aluminium Toxicity
and Drought Stress in Common Bean
(Phaseolus vulgaris L.)
Physiological and Molecular Aspects



Von der Naturwissenschaftlichen Fakultä t der
Gottfried Wilhelm Leibniz Universitä t Hannover
zur Erlangung des Grades

Doktor der Naturwissenschaften
Dr. rer. nat.
genehmigte Dissertation



von
Master of Agriculture Zhongbao Yang
geboren am 28.11.1979 in Tancheng, VR China


2011

























Referent: Prof. Dr. rer. agr. Walter J. Horst
Gottfried Wilhelm Leibniz Universitä t Hannover
Korreferent: Prof. Dr. rer. nat. Hans-Peter Braun
Gottfried Wilhelm Leibniz Universitä t Hannover
Tag der Promotion: 07.Juli 2011

ABSTRACT
Aluminium (Al) toxicity and drought are two major abiotic stress factors limiting common bean
(Phaseolus vulgaris L.) production in the tropics. The Al-impeded root growth may strongly limit the
water exploitation of roots from subsoil and thus less ability to withstand drought stress in the acid soils.
In light of the importance of root development under Al toxicity and drought stress, in this study the
short-term effects of combined Al toxicity and drought stress on root growth with special emphasis on
physiological and molecular mechanisms in the root apex was investigated.
Using hydroponics, PEG 6000 (polyethylene glycol)-induced osmotic (drought) stress reversed the
Al-induced inhibition of root elongation by reducing Al accumulation in the root tips in the Al-sensitive
genotype VAX 1, which was related to the reduction of cell-wall (CW) porosity resulting from
PEG 6000-induced dehydration of the root apoplast. Less Al stress in PEG-treated roots was confirmed
by the expression of the Al-sensitivity indicator genes: multidrug and toxin extrusion family protein
(MATE) and 1-aminocyclopropane-1-carboxylic acid oxidase (ACCO). Transcriptional analysis using
SuperSAGE (serial analysis of gene expression) and quantitative RT-PCR (qRT-PCR) suggested that
genes related to CW assembling and modification such as xyloglucan endotransglucosylase/hydrolase
(XTH), glucan endo-1,3-beta-glucosidase (BEG) and hydroxyproline-rich glycoprotein (HRGP) play
important roles in PEG-induced decrease of CW porosity leading to reduced Al accumulation in root
tips. A large-scale proteomic analysis revealed that dehydrin (DHN) may play a key role in the
protection of osmotic stress-induced physical breakage of CW and thus the maintenance of reversible
CW extensibility.
Under soil conditions, drought reduced Al toxicity in the common bean genotype VAX 1, indicated as
the reversion of Al-induced enhancement of callose content and of MATE gene expression in the root
tips. However, in contrast to PEG-induced reduction of Al injury in hydroponics, combined Al and
drought stress in soil resulted in a more severe inhibition of root elongation than either stress alone. This
is consistent with enhanced further up-regulation by Al of the drought-induced ACCO gene involved in
the biosynthesis of ethylene by Al and the down-regulation by Al of drought-induced
genes/transcription factors in the root tips: the 9-cis-epoxycarotenoid dioxygenase (NCED) gene
involved in ABA biosynthesis, the transcription factors bZIP and MYB involved in the regulation of
ABA-dependent genes, the ABA-dependent sucrose synthase (SUS) gene, the late embryogenesis
abundant (PvLEA18) gene, the KS-type dehydrin (KS-DHN) gene, and the lipid transfer family protein
(LTP) gene.
Together, the results provide circumstantial evidence that PEG-induced osmotic stress and low soil
moisture alleviates Al toxicity, but Al renders the root apex more sensitive to low soil moisture
particularly by impacting the gene regulatory network involved in ABA signal transduction and ABA
signal cross-talk with other phytohormones necessary for maintaining root growth under drought.
Key words: aluminium toxicity and drought stress, common bean, cell wall porosity
I
KURZZUSAMMENFASSUNG
Aluminium (Al)-Toxizitä t und Trockenstress sind zwei wichtige abiotische Stressfaktoren, die die
Produktivitä t von Buschbohne (Phaseolus vulgaris L.) in den Tropen begrenzen. Durch Al-Angebot
gehemmtes Wurzelwachstum kann die Wasseraufnahme aus dem Unterboden stark beeinträ chtigen und
damit die Trockenresistenz von Buschbohne auf sauren Bö den vermindern. Angesichts der Rolle des
Wurzelwachstums fü r Al-Toxizitä t und Trockenstress wurde in dieser Arbeit die kurzfristige Wirkung
von kombiniertem Al und Trockenstress auf das Wurzelwachsum mit besonderer Berü cksichtigung
physiologischer und molekularer Mechanismen in der Wurzelspitze untersucht.
In Hydroponik verminderte PEG 6000 (Polyethylenglycol) induzierter osmotischer (Trocken) Stress
die Hemmung des Wurzellä ngenwachstums durch Al durch eine verminderte Al Akkumulation in der
Wurzelspitzen im Al-sensitiven Buschbohnengenotyp VAX 1. Dies wurde zurü ckgefü hrt auf eine
Verminderung der Zellwandporositä t hervorgerufen durch die Dehydrierung des Wurzelapoplasten
durch PEG. Geringerer Al Stress in PEG behandelten Wurzeln wurde bestä tigt durch eine verminderte
Expression Al-sensitiver Indikatorgene: multidrug and toxin extrusion family protein (MATE) and
1-aminocyclopropane-1-carboxylic acid oxidase (ACCO). Eine Transcriptionsanalyse mit SuperSAGE
(serial analysis of gene expression) and quantitative RT-PCR (qRT-PCR) ergab, dass an der
Zellwandsynthese und -struktur beteiligte Gene wie z.B. Xyloglucan endotransglucosylase/hydrolase
(XTH), Glucan endo-1,3-beta-glucosidase (BEG) und Hydroxyproline-rich glycoprotein (HRGP) eine
wichtige Rolle bei der durch PEG verursachten verminderten Zellwandporisitä t, die zu einer
verminderten Al Akkumulation in Wurzelspitzen fü hrt, spielen. Eine umfassende proteomische Analyse
ergab, dass Dehyrin eine Schlü sselrolle fü r den Schutz der Zellwand vor irreversibler Schä digung durch
Entwä sserung bei osmotischem Stress durch PEG zukommen kö nnte.
Im Boden fü hrte Trockenstress zu verminderter Al Toxizitä t. Hierauf ließ eine geringere Al-induzierte
Kallose-Bildung und Expression des MATE Genes schließ en. Im Unterschied zu einer geringeren
Hemmung des Wurzelwachstums durch Al in Gegenwart von PEG in Hydroponik, erhö hte Al-Angebot
im Boden die Hemmung des Wurzelwachstums durch Trockenstress. Dies ist konsistent mit einer
verstä rkten Heraufregulierung durch Al des an der Ethylen-Synthese beteiligten ACCO Gens und der
Herunterregulierung durch Al von durch Trockenstress verstä rkt exprimierten
Genen/Transkriptionsfaktoren in den Wurzelspitzen: des an der ABA-Synthese beteiligten
9-cis-Epoxycarotenoid dioxygenase (NCED) Gens, den Transkptionsfaktoren bZIP and MYB, die an der
Regulation ABA abhä ngiger Gene beteiligt sind, des ABA abhä ngigen Sucrose synthase (SUS) Gens,
des Late embryogenesis abundant (PvLEA18) Gens, des KS-type dehydrin (KS-DHN) Gens und des
Lipid transfer family protein (LTP) Gens. Insgesamt lassen die Ergebnisse darauf schließ en, dass PEG
indizierter osmotischer Stress und Trockenstress Al Toxizitä t vermindern. Aluminium-Angebot im
Boden macht die Wurzelspitze allerdings empfindlicher gegenü ber Trockenstress, da Al insbesondere
das die ABA Signaltransduktion regulierende Gen-Netzwerk und die Kommunikation von ABA mit
anderen Phytohormonen, was Voraussetzungen fü r die Aufrechterhaltung des Wurzelwachstums unter
Trockenstress sind, beeinträ chtigt.
Schlagworte: Aluminium-Toxizitä t und Trockenstress, Buschbohne, Zellwandporositä t
II
CONTENTS
ABSTRACT .......................................................................................................................... I
KURZZUSAMMENFASSUNG ........................ II
CONTENTS ...................... III
ABBREVIATIONS ............................................................................................................ VI
GENERAL INTRODUCTION ........................... 1
CHAPTER 1 ....................................................................................................................... 10
ALTERATION OF CELL-WALL POROSITY IS INVOLVED IN OSMOTIC STRESS-INDUCED
ENHANCEMENT OF ALUMINIUM RESISTANCE IN COMMON BEAN (PHASEOLUS VULGARIS L.) 10
Abstract ......................................................................................................................... 11
Introduction .................. 12
Materials and Methods ................................. 14
Plant materials and growing conditions .................................... 14
Diffusion of low molecular weight (LMW) PEG through DMTs and the effect of
LMW PEG on root growth and Al accumulation in the root apex............................ 15
Measurement of root-elongation rate ........................................................................ 15
Collection of root exudates and determination of organic acids in exudates and root
apices ......................................................................................................................... 15
Freeze-fracture scanning electron microscopy 17
Isolation of cell-wall material ................... 17
Determination of pectin and its degree of methylation ............................................. 17
3+ 3+ 2+ 2+Cell-wall binding-capacity and uptake of Al , La , Sr , Rb in 1-cm root apices18
Determination of Al, La, Sr, and Rb ......................................... 18
Statistics analysis ...................................................................... 19
Results .......................................................................................... 20
Discussion ..................................................... 32
CHAPTER 2 ....................... 37
PHYSIOLOGICAL AND MOLECULAR ANALYSIS OF POLYETHYLENE GLYCOL-INDUCED
REDUCTION OF ALUMINIUM ACCUMULATION IN THE ROOT TIPS OF COMMON BEAN
(PHASEOLUS VULGARIS L.) ................................................................................................. 37
Abstract ......................................................... 38
Introduction .................................................................................. 39
Materials and Methods ................................................................................................. 42
III
Plant materials and growing conditions .................................................................... 42
Measurement of root-elongation rate ........ 42
RNA isolation and construction of the SuperSAGE library ..... 42
Sequence homology alignments................................................................................ 43
Primer design for qRT-PCR ...................... 43
First-strand cDNA synthesis and qRT-PCR .............................................................. 45
Confirmation of SuperSAGE expression profiles via qRT-PCR 45
Determination of Al .................................................................. 45
Statistical analysis ..................................... 46
Results .......................................................... 47
Discussion ..................................................................................... 58
CHAPTER 3 ....................... 66
PROTEOMIC ANALYSIS OF POLYETHYLENE GLYCOL-INDUCED OSMOTIC STRESS IN ROOT TIPS
OF COMMON BEAN (PHASEOLUS VULGARIS L.) ................................................................... 66
Abstract ......................................................................................... 67
Introduction .................................................. 68
Materials and Methods ................................................................. 70
Plant materials and growing conditions .... 70
Measurement of root-elongation rate ........ 70
Determination of cell-sap osmotic potential ............................................................. 70
Extraction of total soluble protein ............................................................................. 71
Extraction of apoplastic proteins ............... 71
Two dimensional isoelectric focusing (2D IEF) / sodium dodecyl
sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) ...................................... 72
Image acquisition, image analysis and statistical analysis ........ 73
Mass spectrometric analysis and data interpretation ................................................. 73
Statistical analysis ..................................................................... 75
Results .......................................................... 76
Discussion ..................................................................................... 87
CHAPTER 4 ....................... 95
PHYSIOLOGICAL AND MOLECULAR ANALYSIS OF THE INTERACTION BETWEEN ALUMINUM
TOXICITY AND DROUGHT STRESS IN COMMON BEAN (PHASEOLUS VULGARIS L.) ................. 95
Abstract ......................................................................................................................... 96
Introduction .................. 97
IV
Materials and Methods ............................................................................................... 100
Soil properties and preparation ............................................................................... 100
Plant materials and growing conditions .. 101
Measurement of root elongation rate ...................................................................... 101
RNA isolation and quantitative real time-PCR ....................................................... 102
Candidate gene selection and primer design for qRT-PCR ..... 102
Determination of Al ................................................................................................ 103
Determination of callose ......................... 103
Analysis of phytohormones .................................................................................... 103
Statistical analysis ................................................................................................... 105
Results ........................................................ 106
Discussion ................................................................................... 120
GENERAL DISCUSSION .............................. 130
OUTLOOK ...................................................... 139
REFERENCES ................................................................................ 144
SUPPLEMENTAL DATA ............................................................................................... 165
SUPPLEMENTAL DATA FOR CHAPTER 1 ................................ 166
SUPPLEMENTAL DATA FOR CHAPTER 2 168
SUPPLEMENTAL DATA FOR CHAPTER 3 ................................ 208
SUPPLEMENTAL DATA FOR CHAPTER 4 ................................ 211
CURRICULUM VITAE .................................. 216
ERKLÄRUNG ZUR DISSERTATION ......................................................................... 218
ACKNOWLEDGEMENTS ............................ 219

V
ABBREVIATIONS
2D Two dimensional
AAO abscisic aldehyde oxidase
ABA Abscisic acid
ABRE ABA-responsive element
ACCO 1-aminocyclopropane-1-carboxylic acid oxidase
ACO aconitase
ALMT Al-activated malate transporter
ANOVA analysis of variance
AQP aquaporin
BEG Glucan endo-1,3-beta-glucosidase
bp base pair
bZIP basic domain/leucine zipper
CBB Coomassie Brilliant Blue
CK cytokinin
CKX cytokinin oxidase/dehydrogenase
CPC cytosolic protein contamination
CS citrate synthase
CW cell-wall
CWP cell wall protein
CYP701A cytochrome P450 monooxygenase CYP701A
CYP735A cytochrome P450 monooxygenase 735A
cZ cis-zeatin
cZR cis-zeatin riboside
cZRMP cZR 5‘-monophosphate
DHN dehydrin
DM degree of methylation
DMAPP dimethylallyl diphosphate
DMT dialysis membrane-tube
DPS Diamond Phosphoprotein Stain
DTZ distal transition zone
DZ dihydrozeatin
DZR dihydrozeatin riboside
DZRMP DZR 5‘-monophosphate
ECEC effective cation exchange capacity
EST expressed sequence tag
EZ elongation zone
VI
GaE galacturonic acid equivalent
GFAAS graphite furnace atomic absorption spectrophotometer
GO gene ontology
HESI heated electrospray ionization
HPLC high pressure liquid chromatography
HRGP hydroxyproline-rich glycoprotein
IAA indole-3-acetic acid
ICDH isocitrate dehydrogenase
ICP-MS inductively coupled plasma mass spectroscopy
IEF isoelectric focusing
6 2iP N -(Δ -isopentenyl)-adenine
IPG immobilized pH gradient
6 2iPR N -(Δ -isopentenyl)-adenine riboside
iPRDP iP riboside 5‘-diphosphate
iPRMP iP riboside 5‘-moophosphate
iPRTP iP riboside 5‘-triphosphate
IPT adenosine-phosphate isopentenyl-transferase
JA jasmonic acid
KDa kilodalton
kPa kilopascal
KS-DHN KS-type dehydrin
LA-ICP-MS laser ablation inductively coupled plasma mass spectrometry
LEA late embryogenesis abundant
LMW low molecular weight
LTP lipid transfer protein
MATE multidrug and toxic compound extrusion
MDH malate dehydrogenase
MetS methionine synthase
MIPS myo-inositol 1-phosphate synthase
MS mass spectrometry
MWCO molecular weight cut off
NCED 9-cis-epoxycarotenoid dioxygenase
OA organic acid
OP osmotic potential
OS osmotic stress
P5CS Δ1-pyrroline-5-carboxylate synthase
PAGE polyacrylamide gel electrophoresis
PCV pyrocatechol violet
PEG polyethylene glycol
VII
PEPC phosphoenolpyruvate carboxylase
PGM phosphoglycerate mutase
PHGDH D-3-phosphoglycerate dehydrogenase
PIP plasma membrane intrinsic protein
PME pectin methylesterase
PR Pathogenesis-related protein
PRP proline-rich protein
qRT-PCR quantitative real-time polymerase chain reaction
RC recovery
RNA ribonucleic acid
ROS reactive oxygen species
SA salicylic acid
SAGE serial analysis of gene expression
SAM S-adenosylmethionine
SAMS S-adenosylmethionine synthethase
SDS sodium dodecyl sulphate
SEM scanning electron microscope
SSH suppression subtractive hybridization
SUS sucrose synthase
SWP soil water potential
Tris tris(hydroxymethyl)aminomethane
TZ transition zone
tZ trans-zeatin
tZR trans-zeatin riboside
tZRDP tZR 5‘-diphosphate
tZRMP tZR 5‘-monophosphate
tZRTP tZR 5‘-triphosphate
UDP Uridine diphosphate
UniTags unique transcripts
XET xyloglucan endotransglucosylase
XTH xyloglransglucosylase/hydrolase
ZEP zeaxanthin epoxidase
ZOG zeatin-O-glucoside
ZOGT zeatin-O-glucosyltransferase
ZR zeatin-riboside
βGlc β-glucosidase
VIII