Article 14076 of rec.gardens:
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From: klier@iscsvax.uni.edu
Newsgroups: rec.gardens
Subject: Re: F1 Hybrids
Message-ID: <1993Feb27.103541.11232@iscsvax.uni.edu>
Date: 27 Feb 93 10:35:41 -0600
References: <1993Feb26.140705.8370@credence.com>
Organization: University of Northern Iowa
Lines: 35

In article <1993Feb26.140705.8370@credence.com>, steveh@or.credence.com (Steve Holder) writes:
>   I have a question that has been lingering around in the annoyance
>   center of my brain for a few years.  How do commercial seed providers
>   maintain parent stock for F1 hybrids?  My understanding of the
>   creation of an F1 hybrid is that two or more parent lines are
>   generated through successive inbreeding for desired traits.  Then the
>   two lines are cross bred to come up with the F1 seed.

Yep, you've got the main ideas.  Maintaining parental lines is a very
important part of the seed breeding process, with lots of time and energy
expended on maintaining the same genetic stocks.  Usually this involves
growing the parental stocks in locations remote from any other strain of
that plant.  There are tables of required isolation distances for different
types of plants (and different pollinators).   Reputable seed companies
also maintain a constant check on how the currently used parental strain
compares with the originally used strain-- sometimes just visual checks,
but more often these days they use isozyme electrophoresis or one of
the DNA fingerprint techniques.

Another reason why F1 seed is so expensive is that the inbred parents
are generally pretty feeble plants from so much inbreeding.  So the
seed yield is low.  You can really see this "inbreeding depression"
in the seed corn stocks that are raised around here-- many are kinda
mangy and chloritic, and look like putting out a single small ear is
almost too much for them.  This is in sharp contrast to the gigantic,
lush, green F1's with three huge ears per stalk.

Seed corn companies (the ones I'm most familiar with) contract with
local farmers to produce the F1 seeds, and sometimes the inbred
parents.  It's a really picky job growing the seed, and the yields
are pretty low per acre.  Nevertheless, the companies pay a nice
bonus for delivering good seed, and seed corn production is much more
lucrative than most of the other crops commonly grown here.

Kay Klier  Biology Dept  University of Northern Iowa


