Plant Development and Chimeras Quiz

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Questions and Answers

How can true to type periclinal chimeras be propagated effectively?

By separating the chimera genotypes

By using tissue culture from the entire plant

Through seed propagation

By grafting cuttings from the tip (correct)

What is a common manifestation of chimera aside from variegation?

Faster growth rate

Increased ploidy level

Thorn development

Loss of epidermal appendages (correct)

Which statement is true about the role of tissue culture in modern agriculture?

Tissue culture has no impact on agricultural sciences.

Tissue culture has no contribution to somaclonal variation.

It allows for disease-free plant propagation through mass micropropagation techniques. (correct)

It primarily focuses on creating genetically heterogenous plant materials.

What is a key benefit of tissue culture in relation to germplasm conservation?

Enabling cryopreservation for germplasm conservation. Signup and view all the answers

What is the consequence of a cell mutation near the crest of the apical dome?

All cells produced from it will be of the mutated type, leading to chimera formation. Signup and view all the answers

How can chimeras be induced?

Spontaneously through natural genetic variation. Signup and view all the answers

Why are chimeral patterns in plant tissues important?

For recognizing stability and vegetative propagation potential. Signup and view all the answers

How are chimeras described in terms of cell layers?

Using upper case letters in sequence to represent genetic composition. Signup and view all the answers

What is the characteristic of chimeras that arise from mutations near the apical dome?

Cells of different genotypes grow adjacent to each other in plant tissue. Signup and view all the answers

Why is careful observation of coloration in variegated dicot leaves essential for recognizing chimeras?

For distinguishing layers in the shoot apex based on color pattern differences. Signup and view all the answers

What is the main site of cell division in a plant where most cells producing the plant body are formed?

Apical meristem Signup and view all the answers

Which region in the shoot apex exhibits a controlled pattern of cell division resulting in the maintenance of discrete layers?

Tunica Signup and view all the answers

What is the primary function of the tunica in the shoot apex of a plant?

Layering formation Signup and view all the answers

Which factor interacts to determine the type of chimera produced and the stability of the pattern in a plant?

Pattern and frequency of cell division Signup and view all the answers

In variegated plants, why do some cells appear white despite originating from the same tissue system?

Inability to synthesize chlorophyll Signup and view all the answers

Which part of the apex lacks evident layering but plays a crucial role in chimera formation?

Corpus Signup and view all the answers

Study Notes

Chimeras in Plants

A plant can be a chimera for any trait, not just variegation.
A periclinal chimera with a genetically green, white, and green designation is L.I, L.II, and L.III, respectively, which is represented as G-W-G.

Development of Leaf Margins

In dicot leaves, the margins are derived from L.II, and the extent of the leaf margin contributed by L.II varies from species to species and among leaves on an individual stem.
In monocots, L.I contributes to the development of the leaf margin, L.II develops the majority of the central portion of the leaf, and L.III contributes only a small portion of the leaf blade.

Propagation of Chimeras

True to type periclinal chimeras can be propagated through cuttings from the tip and then grafting.
Tissue culture from the meristem of a periclinal chimera can separate the chimera genotypes in some species.

Benefits of Tissue Culture

Tissue culture provides plants needed to meet the world's increasing demand.
It contributes to advances in agricultural sciences and is an important tool in modern agriculture.
It allows the production and propagation of genetically homogenous, disease-free plant materials.
Cell and tissue culture in vitro is useful for introducing somaclonal variation and producing new stable genotypes through the induction of genetic variability.
It enables the production of secondary metabolites, salinity, drought, flooding, heat stress-tolerant plant varieties, and germplasm conservation through cryopreservation.

Origin and Types of Chimeras

Chimeras result from cell mutation, which can be spontaneous or induced by irradiation or chemical mutagens.
If the cell that mutates is located near the crest of the apical dome, all other cells produced by division from it will also be the mutated type, resulting in a chimera.
Periclinal chimeras are the most stable and can be propagated vegetatively.

Recognition of Chimeral Patterns

Determination of chimera layers in the shoot apex is possible through careful observation of the pattern of coloration in variegated dicot leaves.
Describing the nature of the cell layers involves using upper-case letters in sequence to denote the genetic composition of the cells.

Organization of the Shoot Apex

The pattern and frequency of cell division and the layered organization of the cells in the apex interact to determine the type of chimera produced and the stability of the pattern that will be produced.
The apical meristem is the site of cell division, where most of the cells producing the plant body are formed.
Cell division occurrence is fast, leading to cell elongation or expansion, resulting in growth in length of the shoot.

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Description

Test your knowledge on plant development processes and chimeras resulting from cell mutations. Questions cover topics such as the origin of different cell layers in plants and the formation of chimeras due to cell mutations near the apical dome.