A Database for Triticeae and Avena
III.2. Maintenance and multiplication of male sterile stocks without
C. A. Foster. Welsh Plant Breeding Station, Plas Gogerddan, Aberystwyth,
Screening of parental lines to identify pairs giving highyielding heterotic
F1 hybrids is required in the early stages of a hybrid barley programme.
Stocks carrying one of the many male sterile genes available (Hockett et
al., 1968) can be used in the smallscale production of experimental F1
hybrids. For this purpose stocks heterozygous for a male sterile gene must
be isolated by progeny testing. As the progeny of a heterozygous stock
will segregate 3 fertiles to 1 male sterile in their progeny, a large number
of fertiles must be removed from the crossing blocks. Automatic roguing
systems suitable for use in diploid stocks have been proposed, but are
as yet not operational.
A method of maintaining and multiplying a heterozygous male sterile
stock that, firstly, obviates the need for repeated progeny testing, and
secondly, provides seed stocks that will repeatedly segregate a high proportion
of male sterile individuals is as follows:
1. Take a small stock heterozygous for a male sterile gene. In artificial,
or spatial, isolation all the fertile segregants to pollinate the male
steriles. The fertiles will be of two sorts, homozygous (Ms Ms)
and heterozygous (Ms ms) present in the ratio 1 : 2. The pollen
produced by these fertiles will be 2 Ms : 1 ms and the seed
set on the male steriles will be 2/3 fertile; 1/3 male sterile; all the
fertiles being heterozygous.
2. Allow these fertiles to pollinate the male sterile segregants again.
The seed set on these male steriles will in this, and in every subsequent
interpollination, segregate 1 heterozygous fertile to 1 male sterile. Multiplication
or maintenance of the stock, allowing the fertiles to pollinate the steriles,
can be carried out as extensively as required and in every generation the
seed set on the male steriles will segregate 50% male steriles, and all
fertiles will be heterozygous.
By using stocks multiplied in this way repeated progeny testing is not
required, while the seed stock itself is more covenient and economical
to use, in that it segregates 50% male steriles as opposed to the 25% in
the selfed progeny of a heterozygous stock. A range of male sterile stocks
is currently being maintained or multiplied in this way.
Hockett, E. A., R. F. Eslick, D. A. Reid and G. A. Wiebe. 1968. Crop
BGN 2 toc
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