II. 3. The WPBS genetic male sterile barley collection.
C. A. Foster, M. Fothergill and A. D. Hale, Welsh Plant Breeding Station, Plas Gogerddan, Aberystwyth, Dyfed, SY23 3EB, Wales, U.K. "R"
One hundred and seventy-five genetic male sterile and partial male sterile stocks have been submitted to the International collection maintained at Bozeman, Montana. These stocks were isolated from among approximately 2300 sterile plants that have been collected, between 1971 and 1976, during searches for spontaneous genetic male steriles in crops, trials and breeders' nurseries.
The stocks carry collection reference numbers, WPBS stock numbers and most of them have been assigned permanent gene symbols, from msg,,eh to msg,,ix (Hockett, pers. comm.). The F2, F3 and in some cases F4 progenies of the collected sterile plants have been grown and their segregation ratios, anther characteristics and selfing behaviour determined. They range from those which are completely male sterile to those which produce some pollen that is able to effect some self-pollination. The latter are termed partial male-steriles. Anther morphology of the male steriles ranges from those with rudimentary, hair-like structures to those with more or less normal-sized anthers. Many other variants, including female steriles, ovaryless, partial female steriles and semi-steriles (presumably due to reciprocal translocation) and aneuploids, have been found. Few of these have been examined cytologically.
The primary purpose of the collection has been to provide a range of genetic male sterile stocks, in currently cultivated and experimental varieties, that can be used for the production of experimental F1 hybrids. The collection has proved to be invaluable as source material for this purpose. The most promising male sterile stocks have been multiplied by isolating small 3:1 segregating populations in pollen-proof isolation glasshouse units for two generations, taking seed from the male sterile plants at each cycle, to yield stocks segregating 1 fertile:l male sterile (Foster, 1972). Such stocks are more economical to use when hand-roguing segregating stocks in F1 hybrid production plots. The most satisfactory stocks have also been multiplied by the same method on a larger scale in isolated field plots. This method favors the higher seed setting male sterile, since only these provided sufficient seed for intra-population multiplication. These will also set the most F1 hybrid seed in hybrid production plots.
In addition to their use in producing F1 hybrids, some male steriles have been examined in detail by M. Steer and Y. R. Herd at the Queen's University of Belfast. Light microscopy, cytochemistry, SEM and TEM have been used to study pollen development in fertile barley and in 6 genetic male sterile stocks, including msg,,fg, msg,,fp, msg,,fz, mss,,gf and msg,,ho (Herd, 1981). The allelic relationships between some of the most promising stocks and known genes have been studied as part of our own effort on F1 hybrid barley breeding (Dawi and Foster, 1983).
Further collections of male steriles have been made each year from 1977-1982, but these have been less intensively screened. They have yielded 62 genetic male steriles from among 592 collected sterile plants. These have not yet been placed in the International collection or assigned gene symbols.
Of the approximately 2900 sterile plants collected and analysed so far approximately 8% have contained a male sterile gene. Of the male sterile stocks isolated approximately 70% have been complete male steriles, the remainder being partial male steriles or partial steriles of an undefined nature. The collection represents 23 of the 33 spring barley varieties that have been recommended for use in England and Wales in the period 1971-1980. Seven other varieties that have been used, although not recommended, are also represented by male sterile stocks in the collection (Table 1). The majority of the remainder are in breeders' selections and unnamed varieties in trials.
Table 1. Summary of the varietal and male sterile type composition of the WPBS collection.
References:
Dawi, D. A. and C. A. Foster. 1983. Allelism studies of new genetic male sterile stocks in the WPBS collection. BGN 13:9-ll.
Foster, C. A. 1972. Maintenance and multiplication of male sterile stocks without progeny testing. BGN 2:114.
Herd, Y. R. 1981. A comparative light and electron microscopic study of pollen development in male fertile and genetic male sterile barley (Hordeum vulgare L.). Ph.D. Thesis, The Queen’s University of Belfast.
