Style and stigma-Structure & diversity

This PPT intends to explore the structure of stigma & style along with diversity for the sexual reproduction in angiospernms.

1. REPRODUCTIVE BIOLOGY
Welcome to
Structure of Stigma & Style
By N.Sannigrahi, Associate Professor, Department of
Botany, Nistarini College, Purulia, 723101(W.B) India

2. POLLEN GRAINS & STIGMA

3. POLLEN PISTIL INTERACTION
•Pollination→Pollen adhesion→ Pollen hydration→
Pollen germination→ Pollen tube entry into stigma→
Pollen tube growth to the style→ Pollen tube entry
into the ovule and embryo sac → Double fertilization.
•All the events leading from pollination to release of
gametes in the embryo sac form a part of pollen pistil
interaction is called Programic phase.

4. STRUCTURE OF PISTIL
•The female reproductive organ of the flower is called
Gynoecium and the individual member is called
pistil.Pistil is divisible into lower bulbous portion-
Ovary, the long filamentous structure -style and the
upper part of the style called stigma. All the three part
of the pistil enjoy a wide degree of diversity as far as
taxonomic point of view.But whatever may be the
diversity, it is adapted to receive the pollen, aid its
germination and subsequently entry of the pollen tube
into the ovary, ovule and finally into the embryo sac
for fertilization.The ultimate aim to acomplish the
biological actvities as designed for do that.

5. Pistil-Parts and Executives

6. STRUCTURE OF STIGMA
•Stigma-the specialized part where pollen grains are trapped
during pollination.The features of the srtigma has wide
diversity as far as structural composition is cencerned.
•Stigma based on amount of secretion present during receptive
period, decoration of the reseptive surface with glandular cells
or papillae-Wet or Dry,
•The composition of secretion produced by the subepidermal
cells of the stigma highly heterogenous having lipids, proteins,
glycoproteins, amino acids, arbionogalactans, Ca
++
,Phenols.
•Stigma of four types-I, II, III, IV(J. Heslop-Harrison,
1976;Y.Heslop-Harrison & Shivanna, 1977).
•Enzymes are diverse types-non-specific esterases on the
receptive surface, Stigmatic epidermis is covered with cuticle
and some extracelluar protineaceous lipoidal layer called
Pellicle present.
•The layer capture pollen grains and hydration of pollen grains.

7. DIFFERENT TYPES OF STIGMA

8. Structure of Wet Stigma

9. PEROXIDASE ACTIVITY OF STIGMA

10. Structure of Dry Stigma
•In dry stigma, no exudates are released.
•The cuticle is discontinuous,
•Behind the Pellicle & cuticle, thin mucilagenous layer
opresent and the pectocellulosic layer id differentiated into
several layers that form parammural bodies associated with
secrtion of surface components, protein, Polysacchrides,
Constituents of pectocellulosic wall and intercellular matrix.
•In some cases, the pellicle shows ATPase and carbonic
anhydrase activity.
•The pellicle also binds to the lectins and contains
arbinogalactans, a group of carbohydrates with adhesive
properities ( Clarke et al, 1979).

11. FUNCTION OF STIGMA
•FUNCTION
•i.Pollen-Pistil interaction
•ii. Lipoidal components secreted by the stigma to prevent
evaporation and wetting by acting as liquid cuticle,
•iii.Pheolics & Protease inhibitors of stigma give protection
againest insects & pathogens,
•iv.Stigmatic exudates serve as a nutrient sources for
pollinating insects.
•v. Ther pellicle components originate from the epidermal cells
of the stigma or stigmatic papillae shows ATPase and carbonic
anahydrase activity,
•vi. The pellicle binds with lactins and arbinogalactans as
adhesive properities.

12. AFTER POLLEN-PISTIN INTERACTION

13. STRUCTURE OF STYLE
•Style is a tubular structure having the connections between
stima and ovary.
•Mainly of two types-Solid(closed) & Hollow(Open).
•The solid style has a central stand of transmitting tissues of
elongated cells interconnected by plasmodesmata.Intercellular
substances of protinaceous nature surrounded the cells of the
transmitting tissue. It also contains Proteins, glycoproteins and
lipid.A number of transmitting proline rich proteins have been
localized in intercellular matrix(Cheung et al, 1993)The cells
of the transmitting tissue exhibit normal ultrastructural profiles
with numerous mitochondria,active dictyosomes,
roughER,plastids and ribosomes.Pollen tube grow down the
style throgh the intercellular matrix of the transmitting tissue.

14. STYLES OF CARPEL

15. HOLLOW STYLE
•In the hollow style, the central core has one or more canals
which normally correspond to the number of carpels.The stylar
canal is bordered by one or few layers of glandular cells, canal
cells. A layer of cuticle lines the canal cells in the young bud
and the secretion product from the canal cells accumulate
below the cuticle.The canal cells aree glandular and may be
filled with secretion fluid.
•whatever may be, the pollen grains after getting attachment
with the stigma followed by the recognition of the pollen
grains as compatible for germination, either by the sol;id satyle
or the hollow style, a passage is made for the easy
transportation of the pollen grains after germination in the
form of pollen tube until the entire process of the biological
dramas of fertil;iozartuion cme to an end.

16. PATH OF POLLEN TUBE
•The pollen tube pathway depends on the nature of the
stigma.In the species with wet stigma and soild style differs
with that of wet stigma and hollow style.
•In wet stigma and solid style, the cuticle of the stgma or
papillae is disrupted during the secretion of exedutes, thus
there is no physical barrier for the pollen tube entry into the
intcellular spaces before the transmitting tissue of the stigma.
•In the wet stigma with hollow style, pollen tube grows on the
surface of the stigma and enter the stylar canal.
•In the species of the dry stigma and solid style, the cuticle
provides the physical barrier for the pollen tube entry.The
cuticle is eroded at the point of contact by the activity of the
cutineses released by the pollen.After the digestion of the
cuticle, the tube enters the pectocellulosic wall of the papillae
and finally grows throgh the intercellular substances of the

17. Pollen tube guidance
•of the stigma and the style.
•In most of the tissues, pollen tube makes their way to the
ovary though the intercellular matrix of the transmitting tissues
or throgh the mucilagenous matrix of ther hollow style.
Different types of glycoproteins, sugar, proteins plauyed an
important role in this regard.
•The pollen tube finally pushes throgh the ovule and reaches
the embryo sac.The guidance in the ovule is in terms of
essential signal originating from the male and female tissue.In
Arabidopsis, bel1 and sin1-the two genes activate in the
female gametophyte play a crucial role in the signalling
process that guides in the pollen tubes into the ovule.In fact,
pollen tube are always attracted to the ovules with a functional
embryo sac that confirms a female gametophyte control of
pollen tube guidance.

18. DOUBLE FERTILIZATION

19. HOPE, YOU HAVE ENJOYED IT.THANK YOU FOR
YOUR PATIENCE