Totipotency & Organogenesis | Plant Biotechnology - Botany PDF Download

 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.