relates to an organism's ancestry
, an unmixed origin or descent, or a pedigreehttp://www.oxforddictionaries.com/definition/...
• (also pure-bred
) (of an animal or plant) of unmixed origin or descent; pedigree:the pure Charolais is white or light wheat in the coat80 pure-bred stallions were on parade
While two Charolais cattle might both be pure-bred (& produce only Charolais cattle as offspring) they will unlikely be homozygous for every trait that Charolais cattle might have (unless they are identical twins). For instance, the pure-bred Charolais can be either white in the coat or light wheat in the coat. Crossing a white Charolais with a light wheat Charolais will produce offspring that are hybrid as to coat color, but still pure-bred Charolais. The hybrid pure-bred
Charolais will not be true-breeding
as to coat color.True breeding
relates to an organism's offspring
& never relates to all possible traits of an organism (unless they are identical twins) but only one trait at a time (or sometimes to specific combinations of traits).
If I remember my Mendel hybridization experiments correctly:
A garden pea true-breeding for wrinkled seeds will (if self-pollinated) produce only wrinkled-seed offspring, & a garden pea true-breeding for smooth seeds will (if self-pollinated) produce only smooth-seed offspring.
But, if a true-breeding wrinkled-seed garden pea is crossed with a true-breeding smooth-seed garden pea, the offspring will be hybrid smooth-seed garden peas (I hope I remember correctly which one is dominant) that are not true-breeding.
However, these offspring hybrid smooth-seed garden peas that are not true-breeding
will (if self-pollinated) produce 1/4 true-breeding
wrinkled-seed garden peas, 1/4 true-breeding
smooth-seed garden peas, and 1/2
hybrid smooth-seed garden peas that are not true-breeding
Pure-bred organisms may or may not be true-breeding, but will always produce pure-bred offspring if mated with pure-breds of the same breed.
True-breeding organisms may or may not be pure-bred, but will always produce true-breeding offspring if self-pollinated.
Non-true-breeding organisms can produce true-breeding organisms (as much as 1/2 total) if self-pollinated.
I don't know if pure-bred & true breeding should each be two words, one hyphenated word, or one unhyphenated word. And I don't know what the German should be for each. I leave that to others.
P.S. Wikipedia is wrong
in my opinion about true breeding organisms being the same as pure-bred.