Lecture 5 - Root Apex | Plant Anatomy - Biotechnology Engineering (BT) PDF Download

 Page 1


Root Apex 
Institute of Lifelong Learning, University of Delhi 
                
 
 
Lesson Prepared under MHRD project “Natio n al Mission on 
Education through IC T” 
 
Discipline: Botany 
Paper: Plant Anatomy 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Root Apex 
Lesson Developer: Mrs Meenam Bhatia 
Daulat Ram College, University of Delhi 
 
Lesson Reviewer: Dr Vibha Kaushik 
Department/College: Department of Botany, University of Delhi 
Language Editor: Namrata Dhaka 
Department/College: Department of Genetics, University of Delhi, 
South Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
 
 
 
 
Page 2


Root Apex 
Institute of Lifelong Learning, University of Delhi 
                
 
 
Lesson Prepared under MHRD project “Natio n al Mission on 
Education through IC T” 
 
Discipline: Botany 
Paper: Plant Anatomy 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Root Apex 
Lesson Developer: Mrs Meenam Bhatia 
Daulat Ram College, University of Delhi 
 
Lesson Reviewer: Dr Vibha Kaushik 
Department/College: Department of Botany, University of Delhi 
Language Editor: Namrata Dhaka 
Department/College: Department of Genetics, University of Delhi, 
South Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
 
 
 
 
Root Apex 
Institute of Lifelong Learning, University of Delhi 1 
Chapter: Root Apex 
Table of Contents                                                               
? Introduction  
? Anatomy of root apex 
? Cellular organization of root apex 
? Root cap 
? Apical Meristem 
? Zone of Elongation 
? Zone of Maturation 
? Internal organization of apical meristem 
? Apical cell theory 
? Histogen theory 
? Open root meristem 
? Closed root meristem 
? Korper-kappe theory 
? Quiescent center 
? Summary  
? Exercise/ Practice 
? Glossary 
? References 
? Web links 
 
 
 
 
 
 
Page 3


Root Apex 
Institute of Lifelong Learning, University of Delhi 
                
 
 
Lesson Prepared under MHRD project “Natio n al Mission on 
Education through IC T” 
 
Discipline: Botany 
Paper: Plant Anatomy 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Root Apex 
Lesson Developer: Mrs Meenam Bhatia 
Daulat Ram College, University of Delhi 
 
Lesson Reviewer: Dr Vibha Kaushik 
Department/College: Department of Botany, University of Delhi 
Language Editor: Namrata Dhaka 
Department/College: Department of Genetics, University of Delhi, 
South Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
 
 
 
 
Root Apex 
Institute of Lifelong Learning, University of Delhi 1 
Chapter: Root Apex 
Table of Contents                                                               
? Introduction  
? Anatomy of root apex 
? Cellular organization of root apex 
? Root cap 
? Apical Meristem 
? Zone of Elongation 
? Zone of Maturation 
? Internal organization of apical meristem 
? Apical cell theory 
? Histogen theory 
? Open root meristem 
? Closed root meristem 
? Korper-kappe theory 
? Quiescent center 
? Summary  
? Exercise/ Practice 
? Glossary 
? References 
? Web links 
 
 
 
 
 
 
Root Apex 
Institute of Lifelong Learning, University of Delhi 2 
 
Introduction 
The meristems located at the apices of plant organs are called apical meristems. Root apex 
is a term used to refer to the root apical meristem. 
 
Figure: The contribution of shoot apical meristem and root apical meristem to the growth of 
Arabidopsis plant. Both meristems are about 100µm in diameter and contain about 100 
cells. 
Source: http://www.nature.com/nature/journal/v415/n6873/pdf/415751a.pdf 
Root apex is much simpler in its structure than shoot apex. The apical meristem of root can 
be distinguished from shoot apex in lacking the developing appendages like leaf primordia, 
leaf trace or axillary bud. Hence it is continuous and shows no periodic changes in shape 
and structure during its development as shown by shoot apices on leaf initiation. Unlike 
shoot apical meristem, it is bipolar in nature as it adds new cells both distally and 
proximally. The distal cells derivatives give rise to a root cap and the proximal cells elongate 
and differentiate into mature tissue of the root. Thus the growth of root apex is antagonistic 
Page 4


Root Apex 
Institute of Lifelong Learning, University of Delhi 
                
 
 
Lesson Prepared under MHRD project “Natio n al Mission on 
Education through IC T” 
 
Discipline: Botany 
Paper: Plant Anatomy 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Root Apex 
Lesson Developer: Mrs Meenam Bhatia 
Daulat Ram College, University of Delhi 
 
Lesson Reviewer: Dr Vibha Kaushik 
Department/College: Department of Botany, University of Delhi 
Language Editor: Namrata Dhaka 
Department/College: Department of Genetics, University of Delhi, 
South Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
 
 
 
 
Root Apex 
Institute of Lifelong Learning, University of Delhi 1 
Chapter: Root Apex 
Table of Contents                                                               
? Introduction  
? Anatomy of root apex 
? Cellular organization of root apex 
? Root cap 
? Apical Meristem 
? Zone of Elongation 
? Zone of Maturation 
? Internal organization of apical meristem 
? Apical cell theory 
? Histogen theory 
? Open root meristem 
? Closed root meristem 
? Korper-kappe theory 
? Quiescent center 
? Summary  
? Exercise/ Practice 
? Glossary 
? References 
? Web links 
 
 
 
 
 
 
Root Apex 
Institute of Lifelong Learning, University of Delhi 2 
 
Introduction 
The meristems located at the apices of plant organs are called apical meristems. Root apex 
is a term used to refer to the root apical meristem. 
 
Figure: The contribution of shoot apical meristem and root apical meristem to the growth of 
Arabidopsis plant. Both meristems are about 100µm in diameter and contain about 100 
cells. 
Source: http://www.nature.com/nature/journal/v415/n6873/pdf/415751a.pdf 
Root apex is much simpler in its structure than shoot apex. The apical meristem of root can 
be distinguished from shoot apex in lacking the developing appendages like leaf primordia, 
leaf trace or axillary bud. Hence it is continuous and shows no periodic changes in shape 
and structure during its development as shown by shoot apices on leaf initiation. Unlike 
shoot apical meristem, it is bipolar in nature as it adds new cells both distally and 
proximally. The distal cells derivatives give rise to a root cap and the proximal cells elongate 
and differentiate into mature tissue of the root. Thus the growth of root apex is antagonistic 
Root Apex 
Institute of Lifelong Learning, University of Delhi 3 
i.e., it is occurs in both directions, towards the axis and away from axis.  Also it is sub 
terminal in position because of the presence of a protective tissue root cap at its tip. 
Additionally, it provides a shield to the inner meristematic tissue against the mechanical 
obstacles, root cap cells secrete a complex polysaccharide mucigel (mucilage). It enables 
the root to penetrate the soil by lubricating the passage.  
 
Figure: Diagrammatic sketch of L.S. Shoot tip (A) and root tip (B) of Linum usitatissimum 
Source: Esau, K. 1960. Anatomy of Seed Plants, John Wiley & Sons, Inc., NY. 
Page 5


Root Apex 
Institute of Lifelong Learning, University of Delhi 
                
 
 
Lesson Prepared under MHRD project “Natio n al Mission on 
Education through IC T” 
 
Discipline: Botany 
Paper: Plant Anatomy 
National Coordinator: Prof. S.C. Bhatla 
 
Lesson: Root Apex 
Lesson Developer: Mrs Meenam Bhatia 
Daulat Ram College, University of Delhi 
 
Lesson Reviewer: Dr Vibha Kaushik 
Department/College: Department of Botany, University of Delhi 
Language Editor: Namrata Dhaka 
Department/College: Department of Genetics, University of Delhi, 
South Campus 
 
Lesson Editor: Dr Rama Sisodia, Fellow in Botany ILLL 
 
 
 
 
 
 
Root Apex 
Institute of Lifelong Learning, University of Delhi 1 
Chapter: Root Apex 
Table of Contents                                                               
? Introduction  
? Anatomy of root apex 
? Cellular organization of root apex 
? Root cap 
? Apical Meristem 
? Zone of Elongation 
? Zone of Maturation 
? Internal organization of apical meristem 
? Apical cell theory 
? Histogen theory 
? Open root meristem 
? Closed root meristem 
? Korper-kappe theory 
? Quiescent center 
? Summary  
? Exercise/ Practice 
? Glossary 
? References 
? Web links 
 
 
 
 
 
 
Root Apex 
Institute of Lifelong Learning, University of Delhi 2 
 
Introduction 
The meristems located at the apices of plant organs are called apical meristems. Root apex 
is a term used to refer to the root apical meristem. 
 
Figure: The contribution of shoot apical meristem and root apical meristem to the growth of 
Arabidopsis plant. Both meristems are about 100µm in diameter and contain about 100 
cells. 
Source: http://www.nature.com/nature/journal/v415/n6873/pdf/415751a.pdf 
Root apex is much simpler in its structure than shoot apex. The apical meristem of root can 
be distinguished from shoot apex in lacking the developing appendages like leaf primordia, 
leaf trace or axillary bud. Hence it is continuous and shows no periodic changes in shape 
and structure during its development as shown by shoot apices on leaf initiation. Unlike 
shoot apical meristem, it is bipolar in nature as it adds new cells both distally and 
proximally. The distal cells derivatives give rise to a root cap and the proximal cells elongate 
and differentiate into mature tissue of the root. Thus the growth of root apex is antagonistic 
Root Apex 
Institute of Lifelong Learning, University of Delhi 3 
i.e., it is occurs in both directions, towards the axis and away from axis.  Also it is sub 
terminal in position because of the presence of a protective tissue root cap at its tip. 
Additionally, it provides a shield to the inner meristematic tissue against the mechanical 
obstacles, root cap cells secrete a complex polysaccharide mucigel (mucilage). It enables 
the root to penetrate the soil by lubricating the passage.  
 
Figure: Diagrammatic sketch of L.S. Shoot tip (A) and root tip (B) of Linum usitatissimum 
Source: Esau, K. 1960. Anatomy of Seed Plants, John Wiley & Sons, Inc., NY. 
Root Apex 
Institute of Lifelong Learning, University of Delhi 4 
 
A.       B. 
Figure: A.L.S. Coleus shoot apex; B. L.S. Root apex 
Source:http://www.doctortee.com/cgi/image-lookup.cgi?coleus-stem-tip 
;www.daviddarling.info/encyclopedia/P/plant_root.html