Plant Reproduction and Breeding Topic 3 Selective Breeding

Plant Reproduction and Breeding Topic #3

Selective Breeding Selective breeding means that people have chosen specific plants with particular characteristics and encouraged these plants to reproduce Example: Canadian researchers were responsible for developing canola (Canadian + oil). The original plant was rapeseed, but they selectively bred rapeseed plants that produced a good-tasting oil. Work continues with breeding to produce crops that are resistant to disease, drought and even chemicals – THINK MONSANTO http: //www. monsanto. ca/Pages/default. aspx

Genetic Modification Plant scientists now have the ability to make changes to plants by going inside a plant cell and changing some of its material (genetic code) They can take genes and combine them with genetic material from other plants. This is put back into the plant and is used to create a new plant. This process is called genetic modification, but is more commonly called genetic engineering

Vegetative (Asexual) Reproduction Asexual reproduction occurs when a “parent” plant grows new plants from its roots, stems or leaves. Grafting is when you take a branch from one tree and attach it to another, where it will grow and thrive Layering is when a branch from a plant is bent down to the ground and covered with soil. Roots will grow from the buried stem and eventually a new plant will grow

Veg. Rep. (cont) Commercial growers will often use cuttings (small sections of leaf and stem cut from a parent plant) to grow new plants This guarantees that the new plant will be just like the parent

Sexual Reproduction Many trees produce male and female cones. Larger female cones contain ovules (eggs) Smaller male cones contain pollen grains with sperm. Wind carries pollen grains to the female cones, although most never reaches them You’ve probably seen wafts of yellowish pollen in the air

Cones (cont) Once the pollen reaches the female cones, the eggs are fertilized and a tiny seed begins to grow This process is called pollination Female cones then release their seeds, which will get carried elsewhere, buried and will grow a new tree

Flowers are usually bright coloured to attract insects and other animals who will help pollinate the plant while feeding on the plant’s nectar Flowers may also have strong scents to guide insects and animals at night Flowers that aren’t as “showy” often depend on the wind to spread their pollen instead

Parts of a Flower

Pollination can happen in several ways 1) Some plants like barley, self-pollinate – the sperm fertilizes the eggs in the same plant 2) In cross-pollination, the eggs of one plant are fertilized by the sperm from another plant 3) Artificial pollination can also be used where humans are breeding specific plants together for their traits – selective breeding

Disgusting Fruit The last time you ate a piece of fruit, did you realize you were eating the growing ovary and embryo of the plant? Its one purpose is to protect the developing seeds of the plant until they are ready

Seed Dispersal Tumbleweeds Dropping coconuts Fruit-eating birds Sticky burrs Sticky pitch or sap Dandelion “umbrellas/parachutes”

Germination Once the seed has been dispersed and reaches the ground, it stays inactive until the growing condition are right Germination is the development of the seed into a new plant