Meiotic properties in populations of hexaploid Phleum pratense

Abstract

The meiotic properties were studied in two Norwegian populations of Phleum pratense L. (Grindstad and Bodin), one Danish (Pajbjerg) and one Russian population (Rjadovaja). At diakinesis, multivalents in addition to bivalents were found in most of the sporocytes examined, and the mean frequency per sporocyte ranged from 1.09 in Bodin to 1.39 in Grindstad. The differences between populations were not statistically significant. First metaphase was unsuitable for determination of bivalents and multivalents because the chromosomes were clumped together on the equatorial plate. The frequency of MI's with univalents could, however, be determined with certainty, and the average per cent of cells with univalents was 8.7 in Rjadovaja, 18.4 in Pajbjerg, 20.9 in Grindstad and 33.1 in Bodin. Comparisons between the 4 populations showed that Rjadovaja had a significantly lower frequency of MI's with univalents than the others. The remaining populations, on the other hand, did not differ significantly, though the frequency of sporocytes with irregularities at MI and later stages generally was higher in Bodin than in Grindstad and Pajbjerg. The mean frequency of multivalents at diakinesis and first metaphase with univalents varied continuously among plants within populations, and the variation was of the same kind as that found for characters like earliness, plant height etc. Unpaired chromosomes at MI were the most common reason for irregularities at later stages of meiosis and in tetrads, whereas multivalents seemed to play a relatively minor role.