theories of root apex organization concept of quiescent centre development of lateral roots and root hairs functional differentiation

1. ROOT APEX AND VASCULAR
ELEMENTS
Presented by :- Patel Rinku D.
Roll No :- 208
CBO :- 405
M.Sc Sem :- 2
Department of life sciences ,
H.N.G.U., Patan

2. CONTENT
• Theories of Root apex organization :
 Concept of quiescent centre
Development of lateral roots and root hairs
• Vascular elements :
 Functional differentiation

3. Concept of quiescent centre
• Quiescent centre A region in the apical meristem of a root
were cell division proceeds very slowly or not at all , but the
cells are capable of resuming meristematic activity should
tissue surrounding them be damaged .
• Clowes in his autoradiographic studies of DNA synthesis in
the root tip of Zea Mays , Noted a central cup-like region .

5. • The cells of which had fewer mitochondria and ER ,very small
nuclei and low rate of DNA and protein synthesis .
• He referred this inactive region as quiescent centre .
• Since than such regions have been observed in many plants .
• It consists of about 500 cells in Zea mays, 600 in sinapsis .

6. Development of lateral roots and root hairs
 Lateral roots :-
• Lateral roots extend horizontally from the primary root and
serve to anchor the plant securely into the soil .
• This branching of roots also contributes to water up take
and facilitates the extraction of nutrition required for
growth and development of the plant .

7. • Many different factors are involved in the formation of lateral
roots .
• Regulation of root formation is tightly controlled by plant
hormones such as auxin and by the precise control of aspects of
the cell cycle .

9.  Lateral root hairs :-
• A root hair or absorbent hair the rhizoid of a vascular plant is a
tubular outgrowth of a trichoblast a hair forming cell on the
epidermis of a plant root .
• Just prior to the root hair cell development there is a point of
elevated phosphorylase activity .

10. Vascular Elements
• A Vessel elements or vessel member is one of the cell types
found in xylem the water conducing tissue of plants .
• Vessel elements are typically found in flowering plants but
absent from most gymnosperms such as conifers .
• Distinguishing the hard wood of angiosperms from the
softwood of Conifers .

11.  Xylem tissues :-
• Xylem is one of the important tissues of the vascular system of
plants .
• The main activity of this tissue is the transport minerals and
water from roots and carry them to other parts of the plants .

12.  Phloem tissues :-
• Phloem is also important as the xylem tissues for vascular
system of plants .
• The main activity of his tissues is to transport nutrients and
food from leaves to other growing parts of plants .

13.  Cambium :-
• The vascular cambium is the main growth layer in the stems
and roots of many plants specifically in dicots such as butter
cups and oak tress and gymnosperm such as pine trees .
• It produces xylem on the inside and phloem on the outside .

14. REFRENCE
• A Text book of botany plant anatomy and economic botany
volume – 3
by – S.N.Pandey
A. Chadha
https://WWW.encyclopedia.com>Science

15. THANK YOU