| F1 hybrids between three species of Aegilops
and Agropyron intermedium M. MURAMATSU and S. SAKAMOTO Lab. Gen., Kyoto Univ., Kyoto and Nationai Inst. of Genetics, Misima, Japan Three species of Aegilops, i.e. Ae. longissima, cylindrica and variabilis were crossed with Agropyron intermedium with the following results. Ae. longissima x A. intermedium: In 1954 one F1 hybrid was obtained whose somatic chromosome number, examined in root tip cells, was 2n=28 as expected. The ears of this plant resembled those of the Agropyron parent but other characters were intermediate. Pollen- and seed-sterility was complete and the development of the anthers stopped before flowering. Various kinds of chromosome conjugation were observed at MI from 1III+5II+15I to 10II+8I, and the average chromosome conjugation was 0.07IV +1.1III+6.7II+10.9I. 3-4 ring-shaped bivalents were found in each cell. Ae. cylindrica x A. intermedium: One hybrid plant (2n=35) grew slowly and was very weak. Tillering and heading were abnormal. At MI various configurations of chromosomes were found, from 2III+4II+21I to 1III+9II+14I. The average conjugation was 0.1IV+0.9III+6.9II+18I. Ae. variabilis x A. intermedium: Two F1 plants (2n=35) were obtained but one died. Its tillering was good and the bushy growth was like that of the Aegilops parent but the shape of the ears was intermediate. Pollen- and seed-sterility was complete. Various chromosome conjugations from 5II+25I to 10II+15I were observed and the average was 0.5III+6.5II+20.9I. One chromosome fragment was found in every plate. It is noteworthy that in all above mentioned hybrids the average chromosome conjugation amounted to 6-7 bivalents. Hence, autosyndesis between the genomes of A. intermedium may be inferred. The wide fluctuation of the number of bivalents indicates the occurrence of some allosyndesis between the genomes of the employed Aegilops species and A. intermedium. |