Publication Date

1985

Location

Kyoto Japan

Description

A program was designed to sexually produce tetraploid red clover, Trifolium pratense L. adapted to the northern zone of the United States using 2n gametes to effectively transfer diploid (2x) germ plasm to the tetraploid ( 4x) level. Both unilateral (2x-4x and 4x-2x) and bilateral (2x-2x) crosses were conducted using diploid parents which produced 2n gametes. Red clover genotypes were isolated which produced an average of 0.21 2n eggs per 1000 and 12 and 16% tetraploids in unilateral and bilateral crosses, respectively. Genotypes were also identified which either produced 2n pollen exclusively or at a high frequency. Tetraploid and fertile triploid (3x) progeny were derived from bilateral crosses. It was concluded that by using 2n gametes diploid germplasm can be effectively transferred sexually to the tetraploid level, thus avoiding the inbreeding effects which occur with the conventional procedure of chromosome doubling using chemical agents. In addition, 2n gametes may be useful in interspecific germplasm transfer in Trifolium.

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Interploidy Transfer of Germplasm in Red Clover 2N Gametes

Kyoto Japan

A program was designed to sexually produce tetraploid red clover, Trifolium pratense L. adapted to the northern zone of the United States using 2n gametes to effectively transfer diploid (2x) germ plasm to the tetraploid ( 4x) level. Both unilateral (2x-4x and 4x-2x) and bilateral (2x-2x) crosses were conducted using diploid parents which produced 2n gametes. Red clover genotypes were isolated which produced an average of 0.21 2n eggs per 1000 and 12 and 16% tetraploids in unilateral and bilateral crosses, respectively. Genotypes were also identified which either produced 2n pollen exclusively or at a high frequency. Tetraploid and fertile triploid (3x) progeny were derived from bilateral crosses. It was concluded that by using 2n gametes diploid germplasm can be effectively transferred sexually to the tetraploid level, thus avoiding the inbreeding effects which occur with the conventional procedure of chromosome doubling using chemical agents. In addition, 2n gametes may be useful in interspecific germplasm transfer in Trifolium.