Page 1
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 1
Lesson Prepared Under MHRD project “National Mission
on Education Through ICT”
Discipline: Botany
Paper: Plant Biotechnology
National Coordinator: Prof. S.C. Bhatla
Lesson: Totipotency and Organogenesis
Lesson Developer: Dr Gladys Muivah
1
, Dr Vera Kapai
2
, Dr
Samira Chugh
2
Department/College: SGTB Khalsa College
1
, Gargi
College
2
Lesson Reviewer: Dr Rita Arora Sharma
Department/College: School of Life Sciences, Jawaharlal
Nehru University
Language Editor: Vinee Khanna
Department/College: University of Delhi, South Campus
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Page 2
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 1
Lesson Prepared Under MHRD project “National Mission
on Education Through ICT”
Discipline: Botany
Paper: Plant Biotechnology
National Coordinator: Prof. S.C. Bhatla
Lesson: Totipotency and Organogenesis
Lesson Developer: Dr Gladys Muivah
1
, Dr Vera Kapai
2
, Dr
Samira Chugh
2
Department/College: SGTB Khalsa College
1
, Gargi
College
2
Lesson Reviewer: Dr Rita Arora Sharma
Department/College: School of Life Sciences, Jawaharlal
Nehru University
Language Editor: Vinee Khanna
Department/College: University of Delhi, South Campus
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 2
Table of Contents
? Totipotency
? Introduction
? Historical accounts
? Organogenesis
? Basis of organogenesis
? Events during organogenesis
? Factors affecting shoot bud differentiation
? Plant growth regulators
? Explant type
? Genotype of the source plant
? Physical factors
? Summary
? Glossary
? Exercises
? References
Page 3
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 1
Lesson Prepared Under MHRD project “National Mission
on Education Through ICT”
Discipline: Botany
Paper: Plant Biotechnology
National Coordinator: Prof. S.C. Bhatla
Lesson: Totipotency and Organogenesis
Lesson Developer: Dr Gladys Muivah
1
, Dr Vera Kapai
2
, Dr
Samira Chugh
2
Department/College: SGTB Khalsa College
1
, Gargi
College
2
Lesson Reviewer: Dr Rita Arora Sharma
Department/College: School of Life Sciences, Jawaharlal
Nehru University
Language Editor: Vinee Khanna
Department/College: University of Delhi, South Campus
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 2
Table of Contents
? Totipotency
? Introduction
? Historical accounts
? Organogenesis
? Basis of organogenesis
? Events during organogenesis
? Factors affecting shoot bud differentiation
? Plant growth regulators
? Explant type
? Genotype of the source plant
? Physical factors
? Summary
? Glossary
? Exercises
? References
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 3
Totipotency
Introduction
Totipotency can be described as the inherent potential of a plant cell that can give rise to
a whole plant. Totipotency is a developmental phenomenon that separates plant cells
from animal cells. Plants retain this capacity even after the cell has undergone final
differentiation. In plants, as long as the cell have an intact membrane system and a
viable nucleus, even highly mature and differentiated cells retain the ability to regenerate
to a meristematic state. There are mainly three types of cell potency; the differences of
which are given on Table 1:
Table1: Types of cell potency
Totipotency pleuripotency Multipotency
The ability of a single cell to
divide and produce all the
differentiated cells in an
organism, including extra
embryonic tissues.
Example, a plant cutting or
callus can be used to grow
an entire plant.
The potential of a cell to
develop all cell types except
for extra embryonic tissue.
Example, an animal cell
which can differentiate into 3
germ layers i.e. endoderm,
mesoderm and ectoderm.
The ability of a cell to
develop into closely related
family of cells.
Example, a blood stem cell
can develop into types of
blood cells like erythrocytes,
leucocytes etc. but cannot
develop into any other kind
of cell i.e. germ layer cell.
Page 4
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 1
Lesson Prepared Under MHRD project “National Mission
on Education Through ICT”
Discipline: Botany
Paper: Plant Biotechnology
National Coordinator: Prof. S.C. Bhatla
Lesson: Totipotency and Organogenesis
Lesson Developer: Dr Gladys Muivah
1
, Dr Vera Kapai
2
, Dr
Samira Chugh
2
Department/College: SGTB Khalsa College
1
, Gargi
College
2
Lesson Reviewer: Dr Rita Arora Sharma
Department/College: School of Life Sciences, Jawaharlal
Nehru University
Language Editor: Vinee Khanna
Department/College: University of Delhi, South Campus
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 2
Table of Contents
? Totipotency
? Introduction
? Historical accounts
? Organogenesis
? Basis of organogenesis
? Events during organogenesis
? Factors affecting shoot bud differentiation
? Plant growth regulators
? Explant type
? Genotype of the source plant
? Physical factors
? Summary
? Glossary
? Exercises
? References
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 3
Totipotency
Introduction
Totipotency can be described as the inherent potential of a plant cell that can give rise to
a whole plant. Totipotency is a developmental phenomenon that separates plant cells
from animal cells. Plants retain this capacity even after the cell has undergone final
differentiation. In plants, as long as the cell have an intact membrane system and a
viable nucleus, even highly mature and differentiated cells retain the ability to regenerate
to a meristematic state. There are mainly three types of cell potency; the differences of
which are given on Table 1:
Table1: Types of cell potency
Totipotency pleuripotency Multipotency
The ability of a single cell to
divide and produce all the
differentiated cells in an
organism, including extra
embryonic tissues.
Example, a plant cutting or
callus can be used to grow
an entire plant.
The potential of a cell to
develop all cell types except
for extra embryonic tissue.
Example, an animal cell
which can differentiate into 3
germ layers i.e. endoderm,
mesoderm and ectoderm.
The ability of a cell to
develop into closely related
family of cells.
Example, a blood stem cell
can develop into types of
blood cells like erythrocytes,
leucocytes etc. but cannot
develop into any other kind
of cell i.e. germ layer cell.
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 4
Expression of totipotency depends on competence, by which the ability of cells to be
induced along a particular developmental pathway and determination, in which cells
become irreversibly committed to a particular pathway. To express totipotency by a
mature differentiated cell, it first undergoes dedifferentiation followed by redifferentiation.
The phenomenon of a mature cell reverting to the meristematic state and forming
undifferentiated callus tissue is termed dedifferentiation. And conversion of competent
callus cells to whole plant or plant organ is called redifferentiation.
Figure: Totipotency explained in fruit pericarp
Page 5
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 1
Lesson Prepared Under MHRD project “National Mission
on Education Through ICT”
Discipline: Botany
Paper: Plant Biotechnology
National Coordinator: Prof. S.C. Bhatla
Lesson: Totipotency and Organogenesis
Lesson Developer: Dr Gladys Muivah
1
, Dr Vera Kapai
2
, Dr
Samira Chugh
2
Department/College: SGTB Khalsa College
1
, Gargi
College
2
Lesson Reviewer: Dr Rita Arora Sharma
Department/College: School of Life Sciences, Jawaharlal
Nehru University
Language Editor: Vinee Khanna
Department/College: University of Delhi, South Campus
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 2
Table of Contents
? Totipotency
? Introduction
? Historical accounts
? Organogenesis
? Basis of organogenesis
? Events during organogenesis
? Factors affecting shoot bud differentiation
? Plant growth regulators
? Explant type
? Genotype of the source plant
? Physical factors
? Summary
? Glossary
? Exercises
? References
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 3
Totipotency
Introduction
Totipotency can be described as the inherent potential of a plant cell that can give rise to
a whole plant. Totipotency is a developmental phenomenon that separates plant cells
from animal cells. Plants retain this capacity even after the cell has undergone final
differentiation. In plants, as long as the cell have an intact membrane system and a
viable nucleus, even highly mature and differentiated cells retain the ability to regenerate
to a meristematic state. There are mainly three types of cell potency; the differences of
which are given on Table 1:
Table1: Types of cell potency
Totipotency pleuripotency Multipotency
The ability of a single cell to
divide and produce all the
differentiated cells in an
organism, including extra
embryonic tissues.
Example, a plant cutting or
callus can be used to grow
an entire plant.
The potential of a cell to
develop all cell types except
for extra embryonic tissue.
Example, an animal cell
which can differentiate into 3
germ layers i.e. endoderm,
mesoderm and ectoderm.
The ability of a cell to
develop into closely related
family of cells.
Example, a blood stem cell
can develop into types of
blood cells like erythrocytes,
leucocytes etc. but cannot
develop into any other kind
of cell i.e. germ layer cell.
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 4
Expression of totipotency depends on competence, by which the ability of cells to be
induced along a particular developmental pathway and determination, in which cells
become irreversibly committed to a particular pathway. To express totipotency by a
mature differentiated cell, it first undergoes dedifferentiation followed by redifferentiation.
The phenomenon of a mature cell reverting to the meristematic state and forming
undifferentiated callus tissue is termed dedifferentiation. And conversion of competent
callus cells to whole plant or plant organ is called redifferentiation.
Figure: Totipotency explained in fruit pericarp
Totipotency and Organogenesis
Institute of Lifelong Learning, University of Delhi 5
Source:
http://www.jstor.org/stable/pdfplus/1710376.pdf?&acceptTC=true&jpdConfirm=true
Tissue culture techniques offer not only an excellent opportunity to study the factors that
elicit the totipotentiality of cells but also allow investigation of factors controlling
cytological and histological differentiation. Differentiation is the development of organized
structures from undifferentiated tissue or specialized cells that would not normally give
rise to organized multicellular growth. Development of organized structures can follow
one of three pathways:
1. Shoot regeneration, based on a unipolar structure with a shoot apical meristem
2. Root regeneration, essentially a unipolar structure with a root apical meristem
3. Somatic embryogenesis in which there is a bipolar structure
Another type of embryogenesis is through embryo formation from immature post-meiotic
pollen grains (microspores) which leads to production of haploid plants, first reported in
1966 by Guha and Maheshwari when studying meiosis in vitro in Datura innoxia anthers.
Sometimes differentiation takes place in the absence of cell division: in tissue culture
systems, such as Zinnia elegans. Vascular differentiation of tracheary elements has been
extensively investigated using mesophyll cells of Zinnia elegans as model system. For
vascular tissue differentiation, exogenous auxin is important. Kohlenbach and Schmidt
(1975) reported that maximum differentiation of tracheary elements occurs within a
narrow range of both auxin and cytokinin which suggests that the absolute concentration
of the two hormones in the culture medium is more important than auxin/cytokinin ratio.
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