Science Update - Nectarines

Weekly Science Update: Nectarines
Answers to Question 3

P = dominant (peach) gene
p = recessive (nectarine) gene

Every tree has two copies of the gene. If at least one copy of the peach gene is present, the tree will produce peaches.

So, a peach tree can have two different genetic types:

Both dominant (peach) genes: PP
One dominant (peach) and one recessive (nectarine) gene: Pp

But a nectarine tree can ONLY have one genetic type:

Two recessive (nectarine) genes: pp

A tree inherits one copy of the gene from each parent. Therefore, the answers are as follows:

A) Cross two peach trees, get a peach tree

This is possible. Each parent must have at least one dominant (P) gene. If the offspring inherits just one dominant gene, it will produce peaches.

B) Cross two peach trees, get a nectarine tree

This is also possible, if both parent trees have one dominant and one recessive gene (Pp). The offspring would produce nectarines (pp) if it inherited the recessive gene from each of its parents.

C) Cross a peach and a nectarine tree, get a nectarine tree

This is also possible, if the peach tree has one copy of each gene.

D) Cross a peach and a nectarine tree, get a peach tree

This is also possible. The peach tree must have at least one dominant gene. If the offspring inherits that dominant gene, it will be a peach tree.

E) Cross two nectarine trees, get a peach tree

This is NOT possible. Both parents must have two copies of the recessive gene (pp). Therefore, there is no dominant gene for the offspring to inherit.