1. Plant Hybridization & Genetics
Plant Propagation

2. Cross-pollination
Pollen from a plant pollinates the flowers of a different plant of the same species.
Most species of plants are naturally cross-pollinated.

3. Pollen Vectors Things that move pollen from one plant to another: Wind
Insects
Bats

4. Self-pollination
The transfer of pollen from an anther to the stigma of the same flower.
Fewer species of plants are naturally self-pollinating.
Peas are an example. The petals of the flower enclose the reproductive structures making cross-pollination difficult.

5. Hybrid
The offspring of two different plants of the same or closely related species.
Naturally occurring hybrids
Artificially (man-made) created hybrids

6. Naturally Occurring Hybrids
White Oak A
White Oak B X

7. Artificially Created Hybrids
Artificial hybridization of the Garden Pea

8. Artificially Created Hybrids: Seed Corn
Line B planted later
Line A planted early
Line A planted early

9. Artificially Created Hybrids: Seed Corn
Male
Female
Female

10. Artificially Created Hybrids: Seed Corn
Female
Male
Female

11. Artificially Created Hybrids: Seed Corn
Female
Male
Female

12. Artificially Created Hybrids: Seed Corn

13. Artificial Hybrids Can result from crosses made:
Within the same species.
Between varieties, cultivars or lines of a species.
Between two closely related species within the same plant genus.

14. Reasons for Hybridizing Plants
To improve them!
Improve quality
Better resistance to diseases and insects
Improved hardiness
Improved fruit size and quality
Improved flower color
Improved yield
Improved fall color
Resistance to herbicides
Better flavor
Improved storage capabilities

15. Genotype
The genetic makeup of an organism; it’s genes.

16. Phenotype
The outward appearance of an organism; how it looks on the outside.

17. P = G x E
The phenotype of an organism is the result of the interaction between it’s genotype and the environment in which the organism lives.
Michael Jordan vs. good corn, bad corn

18. The Nucleus Command and control center of the cell.
Found in both plant and animal cells.
Contains chromosomes made of the nucleic acid DNA.

19. Onion root cells

20. Genes Segments or sections of chromosomes are referred to as genes.
Genes “code” for the various traits that control and regulate all aspects of plant development, growth and appearance.

21. Genes Just a few examples of what genes code for in plants:
Flower color
Number of stamens, petals, sepals, etc.
Number of ovules in an ovary.
Size, shape and color of the fruit.
Leaf shape and arrangement
Disease resistance
Yield, etc…

22. Genes are segments of chromosomesB C
Genes are segments of chromosomes

23. Monogenic vs. Polygenic Traits
Monogenic traits are coded for by a single gene. Eye color in human beings is an example.
Polygenic traits are coded for by several to many genes (perhaps hundreds of genes). Yield in corn is an example.

24. Somatic Cells
Over 99% of the cells in our bodies, or in a plant, have the identical number of chromosomes.
These “generic” cells are referred to as somatic cells.

25. Oh gross!
The somatic cells in my big toe, for example, have all the genes necessary to make teeth, bones, muscles, a heart, lungs, a liver, etc. The genes are present, just simply not expressed.
In fact it is theoretically possible to re-create a whole, new me from a single cell!

26. Consider that a single root cell has, in it’s nucleus, all the genes needed to make:
Chlorophyll
Leaves
Stems
Flowers
A whole new plant. Get the picture?

27. Totipotency The ability to re-create an organism from a single cell.
First accomplished in plants using Tobacco (Nicotiana).

28. Gametes
There are places, however, in both people and plants where new cells are created that only contain one-half the normal number of chromosomes.
These “sex cells” are called gametes.

29. Plant Gametes In plants there are 2 different kinds of gametes:
Female gamete = egg nucleus (located in an ovule)
Male gamete = sperm nucleus (located in a pollen grain)

30. Fertilization
Occurs when male and female gametes unite.

31. A Human Example… Female Egg 23 chromosomes Male Sperm 23 chromosomes
Baby 46 chromosomes

32. Alleles
Plant (and animal) genes come in different forms called alleles.
For example a hypothetical gene “A” can come in 2 different alleles: A a

33. Gene A codes for flower color.
Plants would have 2 versions (one from each parent) of gene A in varying combinations:
AA = red flowers
Aa = red flowers
aa = white flowers

34. A plant with genotype Aa has what color flowers?
If these 2 plants were crossed could you predict the percentages of the offspring that would have red and white flowers?

35. Parent Aa can produce 2 different gametes: A and a
Punnett Square
Aa X aa
Parent Aa can produce 2 different gametes: A and a
Parent aa can only produce 1 kind of gamete: a A a Aa aa a

36. Results 1 out of 2 (50%) offspring will have red flowers.
1 out of 2 (50%) offspring will have white flowers.

37. A Little More Complicated…
Gene A codes for flower color.
Gene D codes for plant height:
DD = normal height
Dd = normal height
dd = dwarf
What are the gametes that a plant with the genotype AaDd can make?

38. AaDd D = AD A = Ad d D = aD a d = ad

39. Try to predict the outcome of the following cross using a Punnett Square:
Aadd Flower color and size?
Crossed with…
aaDd Flower color and size?
We’ll do this one on the board!

40. The End