Download Plant Reproduction/Propagation

Plant Reproduction/Propagation
Learning Objectives
3) Plant Reproduction/Propagation
a) Develop an understanding of plant genetics
b) Contrast mitosis and meiosis and explain the
significance of each
c) Explain the importance of plant breeding
d) Hypothesize the future influence of biotechnology
on the plant industry
e) Evaluate the significance of sexual propagation of
plants
f) Assess the effectiveness of various types of asexual
propagation of plants
g) Defend the need for Germplasm
Develop an Understanding of Plant
Genetics
• Genes control plant traits
– Phenotype refers to physical characteristics
– Genotype refers to genetic makeup
• Chromosomes and genes separate during
meiosis and resulting gamete contains one
gene for each characteristic (haploid)
– Genes are recombined after pollination (become
diploid)
Contrast Mitosis and Meiosis and Explain
the Significance of Each
Mitosis
Meiosis
•
•
• Makes gametes
• Nucleus divides twice
Makes more genetically identical cells
Nucleus divides once
–
–
•
Four Phases
–
–
–
–
•
•
•
2 diploid cells (2n)
Number of chromosomes remains the
same
Prophase
Metaphase
Anaphase
Telophase
Occurs only during asexual
reproduction
The basic process of vegetative growth
Plants resulting are genetically identical
to parents
– 4 haploid cells (1n)
– Reduces the number of
chromosomes by half
– Nucleus divides twice
– Homologous pairs of chromosomes
separate once while the cell divides
twice
• Two major phases
– Meiosis I
– Meiosis II
• Occurs during sexual
reproduction and only in flowers
Contrast Mitosis and Meiosis and Explain
the Significance of Each
• Compare Mitosis and Meiosis
– http://highered.mheducation.com/sites/0072495
855/student_view0/chapter2/animation__compar
ison_of_meiosis_and_mitosis__quiz_1_.html
• Contrast Mitosis and Meiosis
– http://highered.mheducation.com/sites/0072495
855/student_view0/chapter2/animation__compar
ison_of_meiosis_and_mitosis__quiz_2_.html
Explain the Importance of Plant Breeding
• Plant Breeding
– When reproduction is deliberately controlled and
manipulated, it becomes plant propagation
•
Plants can be bred to have certain desired
characteristics
Evaluate the Significance of Sexual
Propagation of Plants
• Sexual Reproduction
– Requires the fusion of two sex cells (gametes)
•
Forms a cell with two sets of chromosomes, one from
each parent
– Advantages
•
•
•
•
Less expensive than asexual propagation techniques
Many plants can be produced quickly
Genetic crosses result in hybrid vigor
Avoids passing on some diseases
Assess the Effectiveness of Various
Types of Asexual Propagation of Plants
• Asexual Reproduction
– Uses a part or parts of plants of only one parent
plant
– Resulting plant is genetically identical to the
parent plant
– Also known as vegetative propagation
– Advantages
• Less time is required to produce a salable plant
• Plants are genetically identical
• The only way to reproduce some plant varieties
Assess the Effectiveness of Various
Types of Asexual Propagation of Plants
• Runners
– Stems that grow along the ground and form new plants at their nodes
• Stolons
– Aerial shoots that take root after coming into contact with the soil
• Layering
– Roots develop on a stem that is still attached to the parent plant
• Grafting
– Joining the upper portion of a plant with the lower portion of another plant
and fusing them together to become a single plant
• Cuttings
– Pieces of root, leaves, or stems that are removed from parent plant and placed
in an environment that promotes development into total plants
• Tissue Culturing
– Repro of plants from tiny pieces of plant organs; newest propagation
technique
Defend the Need for Germplasm
• Plant Germplasm
– Living tissue from which new plants can be grown
• Seed, leaf, piece of stem, a few cells
• Contains the genetic information for the plants
hereditary makeup
– Needed to preserve the genetic diversity of plants