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1

Chromosome pairing in triploid intergeneric hybrids of Festuca pratensis with Lolium multiflorum, revealed by GISH

100%
Kosmala A., Zwierzykowska E., Zwierzykowski Z.
Journal of Applied Genetics
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2006
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tom 47
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nr 3
Genomic in situ hybridisation (GISH) was used to reveal chromosome pairing in two partly fertile, triploid (2n = 3x = 21) hybrids obtained by crossing the diploid (2n = 2x = 14) Festuca pratensis Huds. (designated FpFp), used as a female parent, with the autotetraploid (2n = 4x = 28) Lolium multiflorum Lam. (designated LmLmLmLm), used as a male parent. The pattern of chromosome pairing calculated on the basis of the mean values of chromosome configurations identified in all 100 PMCs analysed, was: 0.71I Lm + 2.24I Fp + 2.18II Lm/Lm + 0.54II Lm/Fp + 4.18III Lm/Lm/Fp. A relatively high number of Lm/Lm bivalents and Fp univalents, and a low number of Lm/Fp bivalents and Lm univalents indicated that the pairing was preferential between L. multiflorum chromosomes. Other observations regarding chromosome pairing within the Lm/Lm/Fp trivalents also confirmed this preferential pairing in the analysed triploids, as the Fp chromosome was not randomly located in the chain- and frying-pan-shaped trivalents. The similarities and differences in chromosome pairing at metaphase I and the level of preferential pairing between Lolium chromosomes in the different triploid Lolium-Festuca hybrids are discussed.
2
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Meiosis and fertility in spontaneous tetraploids of Festuca pratensis [Huds.]

80%
Wisniewska H.
Journal of Applied Genetics
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1995
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tom 36
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nr 3
The paper is the second part of the studies on spontaneous tetraploids of Festuca pratensis, morphological characters of which were given in the previous article (WIŚNIEWSKA 1994). This paper deals with meiosis in PMCs of spontaneous tetraploids of Festuca pratensis and their F₁ progeny (2n=28) and describes the fertility of these plants in comparison to that of the colchitetraploid cv. Westa and diploid cv. Skrzeszowicka. Different chromosome parings were found in three spontaneous tetraploids. In tetraploid 4/2, most frequently quidrivalents (5.72 IV per 1 PMC) were observed, whereas in tetraploids 465/2 and 534/2, bivalents were prevailing (5.36 and 5.65 II per cell, respectively). The rest of chromosomes remained as univalents, formed trivalcnts and uncountable chromosome associations. Spontaneous tetraploid plants had dehiscent anthers and a high pollen grain fertility (from 78.0 to 94.5%). The degree of seed setting at self-pollination in these plants was low. However, at open pollination, they set a little less seeds than the diploid cv. Skrzeszowicka and the cv. Westa. The plant Si obtained from selfed of spontaneus tetraploids were all tetraploids (2n=28). Seeds obtained from open pollination of spontaneous tetraploids, gave rise to 160 plants of F₁ and all were also tetraploid. No large differences in chromosome pairing.were observed in plants of F₁. At metaphase I a predominant number of bivalents (from 4.72 to 6.05 II) and a smaller number of quadrivalents (from 3.96 to 4.63 IV), were observed. All the plants of F₁ and S₁ generations had dehiscent anthers. Pollen grain viability of Fi plants was high (88.0-90.0%) and similar to that of the parental forms (78.0-89.5%) in the same year of the studies. The average seed setting of all studied F₁ plants at self-pollination ranged from 0.15 to 0.22%, being lower than that of the parental forms. At open pollination it ranged from 34.2 to 36.0%, which was higher than or similar to that of the parental forms in the same year.
3

Cytology and fertility of viable hybrids of Nicotiana tabacum L. cv.TB-566 with N. alata Link et Otto

80%
Laskowska D., Berbec A.
Journal of Applied Genetics
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2005
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tom 46
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nr 1
A vigorous hybrid (N. tabacum cv. TB-566 tetra x N. alata) x N. alata was obtained by backcrossing a partly viable sesquidiploid hybrid N. tabacum cv. TB-566 tetra x N. alata to N. alata. The hybrid was a 35-chromosome near-amphihaploid with a pair of N. alata chromosomes in disomic condition. It was completely self- and cross-sterile and formed from 7 to 8 bivalents in pollen mother cells. By using stem pith culture, polyploidized regenerants were obtained from the 35-chromosome hybrid with somatic chromosome numbers from 65 to 70. These regenerants showed fairly regular meiosis with the number of bivalents in pollen mother cells ranging from 27.3 to 30.4. Irregularities in meiosis included a high number of univalents, aberrant tetrads, and a high frequency of micronuclei. The percentage of acetocarmine-stainable pollen ranged from 22.1 to 78.4. A 66-chromosome regenerant showed fairly regular meiosis and was self-fertile but could not be backcrossed to N. tabacum. This barrier seems to be caused by genic imbalance rather than irregularities of meiotic divisions. Hence transfer programs based on the introgression of entire linkage groups (sexual and somatic hybridization) seem to be of little use in the case of that species.
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