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.

Phenotypic or Molecular Diversity Screening for Conservation of Genetic Resources? An Example from a Genebank Collection of the Temperate Forage Grass Timothy

“…Additionally, four primer combinations from Saltonstall (2001) were screened (trnCF:rpoB, psaI:rbcL, trnS:psbD, and psaA:orf170). The exact segregation pattern of the hexaploid P. pratense is not known, but studies indicate a complex inheritance pattern, and it has not been possible to confirm neither a strict disomic nor polysomic inheritance (see e.g., Nordenskiöld, 1945;Simonsen, 1972). Nested primers exactly the number of homologous alleles at a locus.…”

“…However, it was widespread in all parts of Norway 150 yr ago (Blytt, 1876), so at least one can say that it is naturalized in this region. In addition to its complex inheritance patterns (see e.g., Nordenskiöld, 1945;Simonsen, 1972), one of the hypotheses is that the Nordic timothy is devoid of genetic diversity. However, progress in breeding timothy has been slow in the Nordic region, and the most widespread Nordic cultivar (Grindstad) is still a landrace originating from a farm in the southeastern part of Norway (Opsahl, 1964;Tamaki et al, 2010).…”

“…It is unclear why there is so little progress in breeding of this species. In addition to its complex inheritance patterns (see e.g., Nordenskiöld, 1945;Simonsen, 1972), one of the hypotheses is that the Nordic timothy is devoid of genetic diversity.…”

Cytogenetics, Geographical Distribution, Pollen Stainability and Fecundity of Santolina impressa (Asteraceae: Anthemideae)

“…The plants of S. impressa with chromosome rearrangement manifest considerable sterility, amounting to nearly 50 per cent. The deleterious effect of univalents on pollen stainability observed in S. impressa has been documented by Simonsen (1972) in Phleum pratense, and by Fiona et al (1988) in Solanum muricatum. However, Dnyansagar and Sudhakaran (1970) in Vinca rosea, Merker (1971) in Triticale, Gatt et al (2000) in some hybrids of Dahlia, and Palma-Silva et al (2004) in Vriesea and Aechmea demonstrated that the frequency of univalents is not correlated with pollen stainability.…”

“…The deleterious effect of univalents on pollen stainability has been documented by Simonsen (1972) in Phleum pratense, and by Fiona et al (1988) in Solanum muricatum, while other authors showed that the frequency of univalents is not correlated with pollen stainability. Such studies include those by Dnyansagar and Sudhakaran (1970) in Vinca rosea, Merker (1971) in Triticale, Gatt et al (2000) in some hybrids of Dahlia, and Palma-Silva et al (2004) in Vriesea and Aechmea.…”