1. Plant Reproduction System
PLANT BREEDING AGR 3204
Plant Reproduction System

2. Plant Reproduction System
The reproduction mechanism of a particular plant species or the way it reproduces determines
its genetic characteristics
the breeding approach.

3. 1. Sexual Reproduction
Using sex organs to form next generation / to produce seeds.

4. 1. Sexual reproduction (cont.)
Important steps:
Production of gametes (gametogenesis)
Pollination – Transfer of pollen from anther (male organ) to the stigma (female organ).
Fertilization – The union of male and female gametes to produce new genotypes.

9. POLLINATION
Transfer of pollen from anther (male organ) to the stigma (female organ).
Two kinds of pollination,
Self pollination
Cross pollination

10. Self Pollination
Transfer of pollen from anther to stigma of the same flower / plant

11. Self pollination Natural mechanisms that encourages self pollination:
Cleistogamy
Pollination happens when flower is still closed.
Example: Rice

12. Self Pollination (cont.)
Stigma protected by anther
Anthesis and pollination occur instantaneously once the flower blooms.
Many pollen are produced, covering the stigma, hence preventing pollination by pollen from outside.
Example: lime, tomato and chilli
Chilli flower

13. Self pollination (cont.)
3. Stigma and anther protected by other parts of flower.
Male (stamen) and female (pistil) organs covered by keel, i.e. two fused petals.
Example: Leguminosae family, sub-family Papilionoideae.

14. Cross Pollination
Transfer of pollen from anther to stigma of flower of different plant.

15. Cross Pollination(cont.)
Natural mechanisms to promote cross pollination:
Dieocious
Male and female flowers are formed on different plants.
Have male and female plants.
Example: Papaya, salak
Male salak flower
Female salak flower

16. Cross Pollination(cont.)
2. Monoecious
Male and female flowers are in separate positions on the same plant but mature at slightly different times.
Example: Oil palm, corn and rubber.

17. Cross Pollination(cont.)
3. Dichogamy
Anther and stigma from hemaphrodite flower or flower of monoecious plant mature at different times.
Protogyne
Stigma (female flower) matures before anther (male flower).
Example: Potato, cassava and cashew.
Protogyne: Potato flower

18. Cross Pollination(cont.)
3. Dichogamy (cont.)
Protandry
Anther (male flower) matures before stigma (female flower).
Example: Starfruit and rubber.
Protandry: Starfruit flower

19. Cross Pollination(cont.)
4. Self-incompatibility
Pollens are unable to fertilize ovule (female gamete) of the same flower/plant due to genetic factor (self incompatibility gene)
Example: Potato, passion fruit and starfruit.

20. Cross pollination(cont.)
In some species, there are more than one mechanism to promote cross pollination:
Rubber and corn: monoecious and protandry.
Potato, Sweet potato: Self- incompatibility and protogyne
Starfruit & passion fruit: Self- incompatibility and protandry

21. Methods to determine modes of pollination
1. Identify flower formation system.
2. Isolate plants.
No fruit/seed  cross pollinated
Fruit set/seed set  self pollinated and possibly cross pollinated
3. Selfing.
To observe the effects of inbreeding.
Present  cross pollinated.
Absent / minimal  self pollinated.

22. 2. Asexual Reproduction
Does not involve sex or union of male and female gametes.
Mechanisms:-
Vegetative reproduction
Apomixis

23. Vegetative Reproduction
Stem/branch/root cuttings  e.g. cassava
Grafting  e.g. rubber, rambutan & durian
Rhizome  e.g. tumeric & ginger
Stolon  e.g. grass
Tuber  e.g. potato & sweet potato
Tiller  e.g. pineapple , sugarcane & banana

24. apomixis
Formation of seeds without union of gametes, i.e. fertilization.

25. Apomixis (cont.)
Apogamy – Embryo formation from synergids or antipodals

26. Apomixis (cont.)
Apospory Embryo develops from somatic cell such as nucellus and integument.
Diplospory Embryo develops from megasporocyte.
Adventitious embryo Embryo develops directly from nucellus and integument cells without involving embryo sac cells.
Parthenogenesis Embryo develops from unfertilized eggs.

28. Apomixis (cont.) Obligate apomixis
Apomixis reproduction is the main method of reproduction.
Example: mangosteen

29. Facultative apomixis Both apomixis and sexual reproduction occur.
Example: Guinea grass (Panicum maximum), Citrus sp.

30. Characteristics of cross pollinated, self pollinated and asexual plants
Population
Heterogeneous
Homogeneous
Genotype
Heterozygous
Homozygous
Gamete
Different
Similar
Progeny
Different & heterozygous
Similar & homozygous
Similar & heterozygous
Inbreeding depression
Present
Absent
Incompatibility