II. 4. Allelism studies of new genetic male sterile barley stocks in the WPBS collection.
D. A. Dawi* and C. A. Foster, Welsh Plant Breeding Station, Plas Gogerddan, Aberystwyth, Dyfed, SY23 3EB, Wales, U.K. *Present address: Agricultural Botany Department, Faculty of Agriculture, Shambat, Sudan. "R"
Allelism test crosses have been made between 14 new genetic male sterile stocks and 8 of the numbered male sterile gene series (Dawi, 1981). In all cases crosses were made between a male sterile plant of one stock and a plant known to be heterozygous for the other male sterile gene. Evidence of allelism will be provided by the occurrence of at least one male sterile plant in the F1 progeny, with an expected ratio of 1 fertile to 1 male sterile. A progeny of 7 plants provides a 99% probability of detecting the allelism. Family sizes ranged from 7 to 35.
The new male sterile stocks segregated approximately 3 fertiles:l male sterile in previous tests of fertile heterozygotes (Table 1). The segregation of one, msg,,ha, was low in male steriles, deviating significantly from the 3:1 ratio, at the 5% level of probability. However, all are concluded to be determined by single recessive genes. Eleven of the stocks were completely male sterile. Three were partlal male steriles, showing a trace of pollen production and self-pollination in some conditions.
Table 1. New genetic male sterile stocks tested for allelism with known genes.
The results of the 111 test crosses (Table 2) show that 3 of the new stocks were allelic with one of the numbered genes. Stock msg,,gb therefore becomes msglgb, stock msg,,fr becomes msg5fr and msg,,hg becomes msg24hg.
Additional miscellaneous test crosses have given the following information:
1. msg,,fp and msg,,hr are not allelic with
msgl4;
2. msg,,fg, msg,,fz and msg,,ho
are allelic;
3. msg,,gd and msg,,gw are allelic;
4. msg,,if is not allelic with msgl, msg5,
msg,,hc, msg,,hp or msg,,gd;
5. msg,,gs is not allelic with msgl;
6. msg,,he is not allelic with msg5.
No further allelism test crosses are planned for the immediate future. There are 237 new male sterile stocks in our collection (Foster, Fothergill and Hale, 1983). Approximately 163 are potentially useful, complete or almost complete, male steriles. With at least 33 known genes in the numbered series over 5000 allelism test crosses might be required to complete the program. Of the sample of 122 crosses reported here there were only 6 instances of allelism, representing 4.9% of the crosses. In addition, this series was completed using heterozygous stocks of the new male steriles. These had been prepared for another purpose. Had they not been available fertilies from within segregating families would have been used and approximately seven times as many crosses would have been required to achieve the same result.
References:
Dawi, D. A. 1981. Genetic system for hybrid barley (Hordeum vulgare L.) breeding. Ph.D. Thesis, University of Wales, Aberystwyth.
Foster, C. A., M. Fothergill and A. D. Hale. 1983. The WPBS genetic male sterile barley collection. BGN 13 :6-8
