Contents
IX
5
Apoplastic and Symplastic Proton Concentrations
and Their Significance for Metabolism .............. 103
H. Pfanz
5.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 103
5.2 Definitions... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 104
5.2.1 The pH Concept. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 104
5.2.2 The Buffer Concept ............................... 104
5.2.3 Techniques to Determine Intra- and Intercellular pH . .. 106
5.3 Cellular pH ...................................... 107
5.3.1 The Apoplastic pH ................................ 107
5.3.2 The Symplastic pH ................................ 111
5.4 Conclusions.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 117
References ....................................... 118
6
The Significance of Assimilatory Starch for Growth
in Arabidopsis thaliana Wild-Type
and Starchless Mutants ............................ 123
W. Schulze and E.-D. Schulze
6.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 123
6.2 The Metabolic Pathway of Assimilatory Starch
Formation and the Use of Mutants
to Circumvent Chloroplast Starch Formation ......... 124
6.3 The Diurnal Starch Turnover ....................... 125
6.4 Significance of Leaf Starch for Growth .............. 126
6.4.1 Effects of Leaf Starch on Biomass Formation ........ 126
6.4.2 Effects of Leaf Starch on Regulation
of Shoot/Root Ratios ............................. 128
6.5 The Carbon Balance .............................. 129
6.6 Conclusions..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 130
References ....................................... 131
7
Photosynthesis, Storage, and Allocation . . . . . . . . . . . . . . 133
K. Fichtner, G. W. Koch, and H. A. Mooney
7.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 133
7.2 The Impact of Photosynthesis on Growth, Storage,
and Biomass Allocation in Transgenic Tobacco ....... 133
7.2.1 Photosynthesis and Growth ........................ 134
7.2.2 Photosynthesis and Biomass Allocation .............. 135
7.2.3 Carbon and Nitrogen Storage in Relation
to Photosynthesis ................................. 137
7.2.4 The Tobacco System: Conclusions ................... 138
7.3 Allocation in Relation to Shoot and Root Activity .... 139
7.3.1 Resource, Growth, and Allocation ................... 139
7.3.2 Photosynthesis, Specific Absorption Rate,
and Allocation ................................... 139