CHAPTER
V
DETERMINING FACTORS IN CELL GROWTH:
SOME IMPLICATIONS FOR MORPHOGENESIS IN PLANTS
F.
C. STEWARD and Η. Y. MOHAN RAM
1
I. Introduction
189
A.
The Fertilized Egg and its Environment
189
B.
Some Problems Posed
194
II. Phases and Factors in Cell Growth
196
A.
Stimuli to Cell Division in Plants
196
B.
Stimuli to Growth by Cell Enlargement
207
C.
Inhibitors of Cell Division and Cell Enlargement
213
III. The Regulatory Control of Cell Growth
216
A.
Activation of Quiescent Cells
216
B.
Polarity and Patterns of Cellular Growth
222
C.
Longevity, Senescence and Death of Cells
228
IV. Morphogenetic Considerations
232
A.
Apomictic Development
232
B.
Embryogenesis and Related Problems
233
C.
Centres of Growth in the Vegetative Plant Body
237
D.
The Transition from the Vegetative to the Reproductive State
243
E.
Unorganized Versus Organized Growth
249
V. Summary
255
Acknowledgements
257
References
258
Supplementary list of References
2
265
I. Introduction
A. The Fertilized Egg and Its Environment
The logical starting point for the consideration of morphogenesis in
higher plants is the fertilized egg. This structure, in the special environment of the embryo sac, sets in motion an impressive sequence of
developmental stages through cell divisions. Classical embryology has
furnished the descriptive approach to these problems of cell growth and
cell division and has effectively described what happens, but rarely has
it been able to explain why. It has not been possible, as yet, to remove
the fertilized egg from the environment of an ovule and furnish it with
all the nutrients and the physiological stimuli necessary to achieve the
full range of growth and development which would normally obtain
within the ovule (Fig. 1(a)). Zygote culture, therefore, is an important
ultimate objective. The nutritional stimuli to the development of the
1
Present address: Department of Botany, University of Delhi, India.
2
This chapter was completed in Jan., 1959. Some later additions to the text were
made. References to the literature which were occasioned by these changes and to useful
works published since the paper was first prepared, but which could not be cited in the
text, may be found in the supplementary list of references at the end of the main
bibliography.
189
V
DETERMINING FACTORS IN CELL GROWTH:
SOME IMPLICATIONS FOR MORPHOGENESIS IN PLANTS
F.
C. STEWARD and Η. Y. MOHAN RAM
1
I. Introduction
189
A.
The Fertilized Egg and its Environment
189
B.
Some Problems Posed
194
II. Phases and Factors in Cell Growth
196
A.
Stimuli to Cell Division in Plants
196
B.
Stimuli to Growth by Cell Enlargement
207
C.
Inhibitors of Cell Division and Cell Enlargement
213
III. The Regulatory Control of Cell Growth
216
A.
Activation of Quiescent Cells
216
B.
Polarity and Patterns of Cellular Growth
222
C.
Longevity, Senescence and Death of Cells
228
IV. Morphogenetic Considerations
232
A.
Apomictic Development
232
B.
Embryogenesis and Related Problems
233
C.
Centres of Growth in the Vegetative Plant Body
237
D.
The Transition from the Vegetative to the Reproductive State
243
E.
Unorganized Versus Organized Growth
249
V. Summary
255
Acknowledgements
257
References
258
Supplementary list of References
2
265
I. Introduction
A. The Fertilized Egg and Its Environment
The logical starting point for the consideration of morphogenesis in
higher plants is the fertilized egg. This structure, in the special environment of the embryo sac, sets in motion an impressive sequence of
developmental stages through cell divisions. Classical embryology has
furnished the descriptive approach to these problems of cell growth and
cell division and has effectively described what happens, but rarely has
it been able to explain why. It has not been possible, as yet, to remove
the fertilized egg from the environment of an ovule and furnish it with
all the nutrients and the physiological stimuli necessary to achieve the
full range of growth and development which would normally obtain
within the ovule (Fig. 1(a)). Zygote culture, therefore, is an important
ultimate objective. The nutritional stimuli to the development of the
1
Present address: Department of Botany, University of Delhi, India.
2
This chapter was completed in Jan., 1959. Some later additions to the text were
made. References to the literature which were occasioned by these changes and to useful
works published since the paper was first prepared, but which could not be cited in the
text, may be found in the supplementary list of references at the end of the main
bibliography.
189