Chapter 19 - Clonal Selection Flashcards
advantages of clonal propagation (5)
- Genetic improvement and selections
- Uniformity of populations
- Control of phases of plant development, (earlier bearing of fruit)
- Combine more than one genotype into a single plant,
- Greater commercial value
disadvantages of clonal propagation
- Monoculture
- Slow reproduction rate
- Lack of genetic variation for breeding and selection
- Potential for propagating systemic pathogens from clonal sources
- Insufficient genetic diversity for resistance against unforeseen pests or pathogens
- Potential for latent genetic mutation
What is a bud-sport?
A sudden change in a single branch due to a mutation apparently arising from a single bud.
How can rates of somatic mutations be increased?
The rate of mutation can be increased by treatment with specific mutagenic agents such as X-rays, gamma rays, neutrons, and specific chemicals.
What are reasons why the phenotype might differ in a cloned population?
(a) environment by genotype interactions (phenological changes),
(b) ontogenetic aging (phase changes),
(c) permanent genetic variation,
(d) infection by systemic pathogens or viruses
What is a chimera?
A plant that is composed of a mixture of tissue, with different genotypes that originates within meristematic tissue.
Why can axillary buds, rather than adventitious buds, reliably reproduce chimeras?
due to chimeras only occupying a percentage of the cell layers of a new shoot.
How can meristem-tip culture be used to eliminate viruses from plants?
The small apical dome of a growing point (Fig. 33), including the meristem and a few subtending leaf primordia, is often free of virus and other pathogens even in systemically infected plants. Excision and aseptic culture of this small segment (shoot apex culture) can be the start of a new pathogen-free foundation clone.
clonal “fixing”
The concept of a clone as stabilizing a genotype for propagation.
How can heat treatments and thermotherapy be used to eliminate viruses from plants?
The correct heat kills the pathogen but does not injure the plant. This treatment can be applied to plants, plant parts, bulbs, and seeds to control fungi, bacteria, and nematodes
Why are seedlings usually virus free?
Most viruses either are not trans-mitted through seeds, or the percentage of infected seedlings is low.
ELISA
A specific serological test to determine the antibody reaction to specific viruses.
