stem cell in plant

2. seminar
Stem cell
Supervisor
Dr. Niazi
Provisioner
Nazila gharibi
Spring 1400

3. ➢ Stem cells
➢ Stem cell classification
➢ Embryonic stem cells ( ESC)
➢ Embryonic germ cells (EGC)
➢ Adult stem cell (ASC)
➢ Progenitor cells
➢ Hematopoietic Stem Cells (HCS)
➢ Stem cell comparison
➢ Application of stem cells
➢ Plant stem cells
Over view

4. Stem cells are undifferentiated or partially differentiated cells that can differentiate
into various types of cells and proliferate indefinitely to produce more of the same
stem cell.
stem cells
➢ self-renewal : the ability to go through
numerous cycles of cell growth and cell
division, known as cell proliferation,
while maintaining the undifferentiated
state.
➢ Differentiation : is the process in which
a cell changes from one cell type to
another
Characterized by two unique properties :

6. Stem cell classification based on differentiation potential and
reversibility:
•Totipotent (omnipotent) can give rise
to all the cell types that make up the
body.
•Pluripotent : ability of a single stem
cell to give rise to most but not all the
various cell types i.e. cells derived from
any of the three germ layers.
•Multipotent : ability of a single stem
cell to develop into more than one cell
type of the body.
•Oligopotent : differentiate into only a
few cell types, such as lymphoid or
myeloid stem cells.
•Unipotent cells can produce only one
cell type, their own.

7. Type of stem cell:
➢ Embryonic stem cells ( ESC)
➢ Embryonic germ cells (EGC)
➢ Adult stem cell (ASC)
➢ progenitor cells
➢ induced Pluripotent Stem Cells (IPS)
➢ Bone Marrow Stem Cell:
- Mesenchymal Stem Cells (MSC)
- Hematopoietic Stem Cells (HCS)

9. ➢ Embryonic stem cells ( ESC)
1- Derivation from Blastocyst
2- Unlimited division power, without
differentiation
3- Natural karyotype
4- pluripotency
5- Ability to integrate in all embryonic tissues
6- Germ Line production capacity
7- Cloning
8- Expression of transcription factor Oct-4
9- Directional elicitor (proliferation or
differentiation)
10- No check point G1 in the cell cycle
11- No inactive X chromosome

10. Embryonic stem cell production
process:
1- Isolation of inner cell mass
- Mechanical
- Immunosurgery
2- Transfer to the culture medium
3- Colony formation

11. At the same time experiments:
1. sub-culturing in a few months
2. Determination of cell markers specific to undifferentiated
3. Checking the presence of Oct-4 protein
4. Microscopic study of chromosomes
5. Investigating the ability of cells to divide after freezing
6. Injection into mice with defective immune system

12. Embryonic stem
cells
Adult stem
cells
Source Inner cell mass of
the blastocyst of
embryo
Tissues
throughout
the body
Status Pluripotent Multipotent
Role Developing
embryo
repair

15. Shoot apical meristem (SAM) Root apical meristem (RAM)
Plant stem cells

16. STEMIN1 gene
CLV3 gene

18. Shoot apical meristem (SAM)
• Organizing center (OC)
• Central zone (CZ)
• Peripheral zone (PZ)
• Rib meristem (RM)
Root
apical
meristem
(RAM)
•
Quiescent
center
(QC)
➢ OC cells express WUS transcription factor
essential for maintaining the stem cell pool
➢ SAM stem cells express the CLV3 gene, and the
secreted CLV3 protein counteracts WUS activity
➢ CLV3 with CLV1 and CLV2 genes. Three CLV genes
- in a feedback loop - restrict stem cell
proliferation
➢ QC cells marks the position of the stem cell niche
➢ Surrounding the QC are the stem cells that divide
asymmetrically to generate all the tissue types

19. Transcription factor movement
through plasmodesmata.
(a) WUSCHEL (WUS) is expressed in the
organizing center, and WUS protein (W)
moves into central zone stem cells. In those
cells, W activates the expression of CLAVATA3
(CLV3), a small signaling peptide that
prevents WUS expression outside the
organizing center. New evidence suggests
that WUS dimers repress CLV3 expression in
the organizing center.
(a) (b) SHORTROOT (SHR) is expressed in the
stele, where it localizes to both the nucleus
and cytoplasm. SHR protein (S) moves into
the endodermis, where it activates the
expression of SCARECROW (SCR). Physical
interaction with SCR sequesters S to the
nucleus, preventing further movement.

20. Fig. Classical concept: The plant body is a product of founder cells (stem cells) located in apical
meristems. During zygotic embryogenesis, plants generate the pluripotent stem cells (blue)
Extended concept: Somatic cells induced by various signals (stress-related /ecotype expression)
to form single totipotent embryogenic stem cells that can proliferate invitro giving rise to the
plant body (SAM & RAM)
Pluripotent versus totipotent
plant stem cells

21. ➢ meristematic zone
➢ elongation zone
➢ differentiation zone
Arabidopsis
seedling
❖
hormones
auxin
and
cytokinin
HORMONES AND PATTERNING
✓ the hormones auxin and
cytokinin are essential for
positioning and maintaining
meristem activity.
✓ In the root, auxin regulates
stem cell divisions, and
cytokinin triggers the transition
to differentiation. These roles
are reversed in the shoot
✓ Each hormone stimulates a
signaling pathway that
culminates in the activation
of transcription factors

22. Hormonal treatment can convert lateral
root primordia into shoot primordia and
switch the characteristic auxin-cytokinin
gradient of a root within a short
developmental window.
Presented is a schematic of how lateral
root primordia responded to hormonal
treatments by Rosspopoff et al,at
different developmental stages (2017).
➢ Early lateral root primordia are
aborted
➢ intermediate-stage lateral root
primordia transition to accumulate
cytokinin in the stem cell niche and
grow to resemble a shoot apical
meristem.
➢ Past a certain stage, lateral root
primordia maintain their characteristic
auxin-cytokinin domains and emerge
as lateral roots.

23. Structural variation at the maize WUSCHEL1 locus alters stem
cell organization in inflorescences
these are traits that depend on populations
of stem cells maintained by the CLAVATA
WUSCHEL (CLV-WUS) negative feedback-
loop that controls the expression of the
WUS homeobox transcription factor
Hypersensitivity to
cytokinin causes stem
cell over proliferation
and major
rearrangements of
Bif3 inflorescence
meristems, leading to
the formation of ball-
shaped ears and
severely affecting
productivity.
the maize dominant Barren inflorescence3 (Bif3) mutant
harbors a tandem duplicated copy of the ZmWUS1 gene,
ZmWUS1-B, whose novel chimeric promoter enhances
transcription in a ring-like pattern.

24. What are currently applications of plant stem cells?
There are plenty of positive cosmetic effects that can be
obtained using plant stem cells, for example:
• increasing the life of fibroblasts and stimulating their
activity (e.g., Oryza sativa, Gardenia Jasmin ides);
• rising the flexibility of the epidermis (e.g., Symphytum
officinale, Capsicum annuum, Opuntia spp.);
• managing cell division (e.g., Oryza sativa, Lotus japonicus);
• fixing damaged epidermis (e.g., Panax ginseng, Opuntia
spp.);
• activating DNA repair of the cells (e.g., Rubus ideas,
Lycopersicon esculentum);
• protecting DNA from oxidative stress (e.g., Citrus limon);
• keeping from harm of UV radiation (e.g., Dolichos biflorus,
Opuntia Ficus indica).

26. Natural processes for creating plant cell
cultures:
selecting/taking away a small piece of the plant
▼
wounding of plant material to induce callus formation
▼
incubation on agar plates
▼
Harvesting of developed callus on solid media
▼
Cultivation until complete dedifferentiation to obtain stem cells
▼
Transfer of the stem cells into a suspension (liquid media)
▼
Adaptation to cold
▼
Disruption of the stem cells wall
▼
encapsulation of stem cells content into liposome (Liposomal extract)

27. Schematic representation of the stepwise process of isolation
of stem cells from Swiss apples (Uttwiler splatlauber)

28. Fig. Workflow depiction of commercial products formation from plant stem cells

29. Thank You