cleistogamy and chasmogamy are mechanisms involved in self pollination

1. BY
B.SUKRUTHA
2020608008
I Ph.D
CLEISTOGAMY and CHASMOGAMY
In PLANTS

2.  First defined by Kuhn (1867) - refers to the
production of bud-like flowers that never opened
but yet developed into fruit. (literally, “closed
marriage”)
 well known in peanuts, peas, and pansy this
behavior is most widespread in the grass family.
 Advantage of cleistogamy - requires fewer plant
resources to produce seeds than does
chasmogamy, because development of petals,
nectar and large amounts of pollen is not
required-This efficiency makes cleistogamy
particularly useful for seed production on
unfavorable sites or adverse conditions
Cleistogamy

3.  Preanthesis cleistogamy
 Pseudocleistogamy/induced cleistogamy
 Complete cleistogamy
 "True" cleistogamy/Dimorphic cleistogamy
Types

4.  Condition where bud pollination occurs followed by anthesis.
 Common in cultivated legumes, grasses and other crop plants.
Preanthesis cleistogamy

5.  Mere lack of floral expansion at anthesis stage.
 Pseudocleistogamous (PCL) flowers usually have the ability to self in the bud so
there may be some subtle physiological modification in the closed flowers of
these species.
 This phenomenon is induced by an environmental factor
 Environment arrests the development of Chasmogamous(CH) flowers prior to
anthesis and results in a mechanical failure of the flower to open, resulting in the
production of a Clesitogamous(CL) flower
 Unfavorable conditions such as drought and low temperatures often promote CL
flower production
Pseudocleistogamy / Induced cleistogamy

6.  Refers to species which produce only CL flowers, such as some orchids and
grasses
 Most indications of complete cleistogamy are based on observations of only a
few individuals, often in artificial environments such as a greenhouse.
Complete cleistogamy

7.  Dimorphic cleistogamy is one form of mixed mating.
 Refers to case where floral dimorphisms result from divergent developmental
pathways in a single species or an individual.
 CL flowers are modified forms of the CH flowers characterized mainly by
reductions in stamen size and/ or number and corolla size. Such reductions are
due to more than a mere lack of expansion at anthesis in the CL flower.
True cleistogamy / Dimorphic cleistogamy

8. Primordial bud is already
predetermined to develop into
either a chasmogamous (CH) or
cleistogamous (CL) flower
No fixed developmental
trajectory, and each bud will
develop into a CH flower unless
the environment prevents its
mechanical opening.
All buds in species with complete
cleistogamy develop into CL
flowers

9.  Plant reproductive mechanism in which pollination occurs
in chasmogamous flowers. Chasmogamous flowers are
commonly showy with open petals encircling exposed
reproductive parts.
 Chasmogamous stems from Greek for "open marriage",
named after the open arrangement of floral
structures. Once chasmogamous flowers have reached
maturity, they unfurl and their stamens and/or style are
made available for pollination.
Chasmogamy

10.  Chasmogamous flowers that are cross-pollinated have the advantage of sexual
reproduction between two different parents, resulting in sexual recombination and
genetically distinct seeds. These distinct seeds increase genetic diversity of the
plant population and reduce inbreeding depression and deleterious alleles
 To promote cross-pollination, chasmogamous flowers often have strikingly
colored petals and nectar guides/nectaries to attract and reward pollinators and
pollination depends upon the availability of pollinating agents.
 These flowers generally develop when resources like light, water, nutrients, and
pollinators are high.

11.  Chasmogamous and cleistogamous are two conditions of flowers, the
reproductive organ of the angiosperms. They have significant adaptations to
encourage a particular type of pollination.
 However, both types of flowers have reproductive structures including stamen
and pistil.
 No morphological differences occur between CL and CH flowers other than a lack
of expansion and anthesis in CL flowers.
Similarities Between Chasmogamous and Cleistogamous

12. CHASMOGAMOUS CLEISTOGAMOUS
Production of flowers that open, so as to
expose the reproductive organs and allow
cross-pollination.
Condition of having small, unopened, self-
pollinating flowers
Large and more prominent Very small and indistinguishable
Have bright colors Less colorful
Have petals to attract pollinators Generally don’t have petals
Open and showy, exposing reproductive
structures to outside
Remain closed and hidden so that anthers
and stigmas never exposed
Undergo cross- pollination Undergo self-pollination
Examples : Pansy Examples : Subularia
Chasmogamous vs Cleistogamous

13. commonly known as the Benghal dayflower, tropical spiderwort, or
wandering Jew, kanshira in Bengali, is a perennial herb native to tropical
Asia and Africa.
Pollination in Commelina bengalensis

14. • Two types of flowers in Commelina :
1) cleistogamous flower and 2) chasmogamous
flower.
• Cleistogamous flower exhibit positive geotropism
and develop inside the soil along with the root,
mostly it is white in colour and its reproductive and
floral parts encircle with petals or closed or do not
open.
• Chasmogamous flower in commelina exhibit
negative geotropism and developed in shoot system
outside the soil, which are brightly coloured, open
and mechanically do not seal.

15.  CL flowers may offer reproductive assurance when pollinators are rare or absent
 CL flowers in some species may be energetically less costly to produce, resulting in
more resources available for seed production.
 CL flowers possess an inherent automatic selfing advantage because both
maternal sets of genes can be passed on to the progeny, in contrast to only one set
of genes passed on to outcrossed offspring.
 CL selfing prevents disruption of locally adapted gene complexes by avoiding the
recombination that frequently accompanies outcrossing.
 Consistent selfing through CL flowers can eliminate deleterious recessive alleles
within populations.
Advantages and Disadvantages of CH and CL Flowers
Advantages of CL

16.  Decreased genetic variation and increased genetic drift.
 High levels of inbreeding depression
 Increased sibling competition among CL seeds that are dispersed within
the immediate vicinity of the maternal plant.
Disadvantages of CL

17.  CH seeds may exhibit heterosis if they result from outcrossing events between
genetically distinct individuals.
 Genetically variable progeny produced by CH flowers would be favored in
spatially or temporally heterogeneous habitats
 CH seeds are often dispersed farther from the maternal plant, thus avoiding
sibling competition
 high energetic cost of production in some species as well as pollinator reliance
for fertilization.
Advantages of CH
Disadvantages of CH

18. Citation: Sternberger AL, Ruhil AVS, Rosenthal DM,
Ballard HE, Wyatt SE (2020) Environmental impact on
the temporal production of chasmogamous and
cleistogamous flowers in the mixed breeding system of
Viola pubescens. PLoS ONE 15(3): e0229726.
https://doi.org/10.1371/ journal.pone.0229726
CASE STUDY
V. pubescens produces chasmogamous
flowers in spring before the canopy closes
and cleistogamous flowers through summer
and early fall following canopy closure

19. Collomia grandiflora
Ratio of chasmogamous to cleistogamous flowers produced per
individual plant rises with increasing light quantity and soil fertility
favorable light and soil conditions leads
to domination of chasmogamous flowers
In contrast, increases in
cleistogamous flowers at higher
light quantities
Viola striata
Oxalis montana

20. Influence of temperature on chasmogamous and
cleistogamous flowering--- winter- cleistogamous
(spring)warmer - chasmogamous
Ceratocapnos heterocarpa
Impatiens capensis
Stipa leucotricha
less available soil moisture leads to a higher
percentage of cleistogamous flowers,
high soil moisture conditions result in
greater chasmogamous flower production

21. Objective
The present research focused on quantitatively analyzing how seasonal changes
affect chasmogamous versus cleistogamous bud production in V. pubescens and
identifying the distinct environmental factors contributing to these effects.
Materials and methods
• 10 plots were established
• Measurements of light quantity, canopy cover, photoperiod, temperature, soil moisture,
soil pH, and the number of chasmogamous and cleistogamous buds were collected on
either a weekly or biweekly basis in 2016 & 2017.

22. Results
• In 2016 – total 77 plants tracked for reproductive behaviour from which
321 chasmogamous and 405 cleistogamous buds
• 2017 - 118 individuals were evaluated with 272 chasmogamous and 387
cleistogamous buds
• Bud counts were collected individually from each of ten plots -weekly and
then biweekly following the transition from chasmogamous to
cleistogamous budding

26. Conclusion
• Offers novel insight into how chasmogamous and cleistogamous bud development may be affected
as global climate change impacts factors like temperature and water availability. and provides
insight into how climatic change may impact mixed breeding species.
• Results of the regressions herein provide a means of predicting chasmogamous and cleistogamous
bud likelihoods under simulated climate conditions offering unique opportunities to forecast future,
phenological patterns and population dynamics for viola sps and possibly other
chasmogamous/cleistogamous mixed breeding species.
• Mixed breeding species like V. pubescens can increase genetic diversity through cross-pollination
of chasmogamous flowers and also assure reproductive success via selfing of cleistogamous
flowers when environmental conditions and resources are unfavorable
• Chasmogamous/cleistogamous mixed breeding system is thought to provide species reproductive
plasticity allowing them to adapt to heterogenous habitats and assure reproductive vigor through
variable environmental and pollinator conditions.
Chasmogamous – more light
Warmer temp
high soil moisture
Cleistogamous – low light
winter temp
less moisture

27. • Lord, E.M. 1981.CLEISTOGAMY: A TOOL FOR THE STUDY OF FLORAL MORPHOGENESIS,
FUNCTION AND EVOLUTION. The Botanical Review. 47: 421-449
• Culley,T and Klooster, M.R. 2007. The Cleistogamous Breeding System: A Review of Its Frequency,
Evolution, and Ecology in Angiosperms. The Botanical Review. 73(1): 1–30. DOI: 10.1663/0006-
8101(2007)73[1:TCBSAR]2.0.CO;2
• Cleistogamy – Google Wikipedia
• Chasmogamy - Google Wikipedia
• Sternberger AL, Ruhil AVS, Rosenthal DM, Ballard HE and Wyatt SE. 2020. Environmental impact
on the temporal production of chasmogamous and cleistogamous flowers in the mixed breeding
system of Viola pubescens. PLoS ONE 15(3): e0229726. https://doi.org/10.1371/
journal.pone.0229726
References
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