6.4.1 Natural Clones in Plants Flashcards
What are natural clones in plants?
Many plants can reproduce asexually using meristem cells, in a process called vegetative reproduction
Vegetative organs of plants include:
Root and shoot tips
Axillary buds (where leaves and the stem meet)
Vascular cambium (between xylem and phloem)
Naturally, over time a young, miniature plant (a plantlet) forms at these locations and remains attached to its parent plant
These plantlets are clones of their parent (as no other DNA has been introduced)
At maturity, the plantlet becomes detached from its parent and can live independently, when it is capable of photosynthesizing by itself
The new plants all have the same phenotype, so are uniform, making growing and harvesting easier
Plants that are hard to grow from seeds can be propagated, eg. orchids for the horticulture industry
Some plants have horizontal stems or runners that form over the soil surface, pointing sufficiently far away so that a new plant at that location will not be overshadowed by its parent, or in competition for water or soil nutrients
Roots form under the nodes of runners, called adventitious roots
The runner dies when the plantlet is self-sustaining
Strawberries, peppermint and spider plants reproduce in this way
What are propagation techniques using vegetative production?
Many methods of propagation do not require seeds as it is not sexual reproduction that is occurring, it is asexual reproduction
A well as runners, plants can propagate asexually using tubers, rhizomes, bulbs, suckers, and offsets
All modes of vegetative propagation contain modified stems that can generate meristematic tissue
Potato tubers are swollen modified roots that form eyes on their surface
Eyes can sprout new growth (called ‘chitting’)
The starch stored in the tuber fuels the early growth of the new plant
Ginger forms rhizomes, a modified stem that grows horizontally underground
New growth stems from nodes in the rhizome, forming new stems and adventitious roots
The section used in cookery is the rhizome
Onions and garlic form bulbs that can grow adventitious roots underground and leafy shoots above ground
Suckers are growths that appear from the root systems of many trees and shrubs, which can provide meristematic tissue for vegetative propagation
Examples are poplars, cherries and plums
Offsets are small, virtually complete daughter plants that have been asexually produced on the mother plant
Examples are tulips and lilies
Gardeners and horticulturalists can use these techniques to propagate desirable species asexually, effectively and at less cost than utilising sexual reproduction techniques
This is done by taking cuttings and dividing up plants into different clumps or sections
