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0:00
Hello.
My name is Nathan Springer.
I am a professor in the
Department of Plant Biology
at the University of Minnesota.
My lab studies maize genetics.
And we have done some research
on the phenomena of heterosis.
Today, I will be talking about
heterosis in agriculture.
0:20
It is useful to
begin with an outline
of what I will talk about today.
First, I want to discuss
what is heterosis, what
is the meaning of this
word, and what are we
describing when we use this word?
Second, what is the
genetic basis of heterosis?
Heterosis is a complex phenomenon.
And it would be useful to better
understand the genetic processes
that might contribute to heterosis.
Third, what are the implications
of heterosis for agriculture?
Heterosis is widely used
in agricultural systems
throughout the world.
And it has some strong implications
for both how seed is produced to go
into fields, as well as
the yield and the types
of plants that are utilized.
1:06
So what is heterosis?
Heterosis refers to
the phenomenon in which
hybrid offspring exhibit
characteristics that lie
outside the range of the parents.
This was initially described
in 1908 by George Shull.
You'll often hear
the term hybrid vigor
and heterosis used interchangeably.
Heterosis is a phenomena that was
formally described by George Shull
when inbred lines were crossed.
But this phenomena can
be observed any time
two related individuals
are crossed or two
unrelated individuals are crossed.
The two pictures on this page show
examples of heterosis in maize.
The picture on the left
shows four ears of corn.
The ears of corn on the far
left and far right of this image
are from the inbred lines
B73 and Missouri 17.
These are two commonly
used lines of corn.
The ears in the middle are F1s.
They are the result of crossing
together B73 and Missouri 17.
You'll notice that the F1
ears are substantially larger
and have more seeds
than either parent.
Similarly, you can see hybrid vigor
for plant growth characteristics
in the picture on the right.
Once again, the two
parents are shown
growing on the two edges of this
image, and the rows in the middle
are F1s.
You'll see that the
F1s have grown faster
and result in more vigorous
plants then either parent.
