It's about the reasons explaining why most organisms receive mitochondrial and chloroplast genome from their mothers only.

1. Why are most organelle genomes
transmitted maternally?
By
Sourya Banerjee
18LPMS12
Advisor-Prof.
G.Padmaja
15/03/2019
Department of Plant Sciences
University of Hyderabad
www.frontiersin.org
https://www.cgm.northwester
n.edu/images/NUSeq/mtDNA-
seq.jpg

2. Introduction

3. Organelle exclusion in plants
Greiner,S., Sobanski,J., Bock, R.(2014) Why are most organelle genomes
transmitted maternally?, Bioessays 37(1),80-94

4. Theoretical models for the occurrence of
uniparental organelle inheritance
1) Genomic conflict models
2) Mutation pressure model
3) Co-adaptation model
All are hypothetical and based on evolution
Greiner,S., Sobanski,J., Bock, R.(2014) Why are most organelle genomes transmitted
maternally?, Bioessays 37(1),80-94.

5. 1)Genomic conflict models
Proposed by Grun
ExpEvening primroses (genus Oenothera)
Avoiding competition
Avoiding negative interaction
https://www.healthline.com/health/evening-primrose-
oil

6. Two non-recombining lineages (i.e. the maternal
and paternal organellar genomes) will enter
direct competition.
Replication speed will determine who will
survive.

7. Repeated origin and loss of uniparental organelle inheritance in
evolution and selection pressures for uniparental and biparental
organelle transmission
Greiner,S., Sobanski,J., Bock, R.(2014) Why are most organelle genomes
transmitted maternally?, Bioessays 37(1),80-94.

8. Negative interaction
There is the possibility that different organelles
harbor different alleles of one locus, and
their heteroplasmic combination is
maladaptive to the cell.
T t T A

9. 2)Mutation pressure model
deleterious mutations of the smaller paternal gamete
can be eliminated effectively by selection
paternal leakage (or biparental transmission) would
interfere with this process.
Fig-Parental
leakage in Tobacco
seedlings
Greiner,S., Sobanski,J.,
Bock, R.(2014) Why are
most organelle genomes
transmitted maternally?,
Bioessays 37(1),80-94.

10. 3)Co-adaptation model
Mathematical modeling shows that co
adaptation was a driving force for uniparental
inheritance and the evolution of two sexes.
https://socratic.org/questions/how-would-you-define-endosymbiotic-theory

11. Other reasons
Maternal organelle is protected from oxidative damage, the
sessile egg cell has a lower energy demand than the
mobile sperm, the paternal oDNA may suffer from higher
oxidative damage.
Maternal germline cells are protected in specialized tissues,
where organelles would display low metabolic rates.
https://tenor.com/search/sperm-cell-
cartoon-gifs

12. Muller’s ratchet
Hermann Muller (left) and lab
members prepare fruit fly media. A
cat drinks from a small saucer on the
table.
https://biology.indiana.edu/news-
events/named-lectures/muller-
about.html
Asexual population accumulates
deleterious mutation.
Sexual reproduction is the
solution as recombination is present.

13. Evolutionary trade of uniparental
inheritance
Source- Why are most organelle genomes transmitted
maternally?Stephan Greiner, Johanna Sobanski and Ralph Bock

14. drawbacks
• Meristem confers plant growth and cellular
differentiation, it has a high energy demand.
Therefore, its mitochondria should not be protected
from reactive oxygen species.
• Hypothesis cannot apply to unicellular
organisms.
• Lack of molecular or cell biological evidence for
negative interactions between co-existing plastids.

15. Conclusion
Future approaches
1.Factors involved in and/or leading to
uniparental (maternal) organelle inheritance
need to be identified and quantified.
2. To identify the genes involved in organelle
exclusion and to investigate their population
genetics.

16. References
• Greiner, S., Sobanski, J., Bock, R.(2014) Why are most organelle
genomes transmitted maternally? Bioessays 37(1),80-94.
• Xu, J.(2006) The Inheritance of organelle genes and genomes:
Patterns and mechanisms. Genome 48(6),951-958.
• Sato, M. ,Sato, K. (2013) Maternal inheritance of mitochondrial
DNA by diverse mechanisms to eliminate paternal mitochondrial
DNA. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research
1833(8),1979-1984.
• Birky, C.W. Jr.(2008) Uniparental inheritance of organelle genes.
Current Biology 18(16),R692-695.

17. Thank you