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Plant regeneration from immature inflorescence-derived callus of Italian ryegrass (Lolium multiflorum Lam.): chromosome number and fertility of regenerated plants

100%

Zwierzykowski Z., Rybczynski J. J.

Journal of Applied Genetics

1998

vol. 39

issue 3

217-224

Twenty field-grown genotypes of diploid Italian ryegrass (Lolium multiflorum Lam., 2n = 2x = 14) were tested for their ability to induce callus and regenerate plants. Callus cultures were initiated from segments of immature inflorescences cultured on the MS medium supplemented with 4.0 mg L-1 2,4-D. The calluses were subcultured first on the maintaining medium (MS medium with 2.0 mg L-1 2,4-D) and later on the rooting medium (MS medium with 0.2 mg L-1 2,4-D). The frequency of callus induction varied depending on the source of explant and the initial genotype. A total of 473 green plantlets were regenerated, of which 420 were established in the soil. All these plants had the morphological characteristics of Italian ryegrass. Among 372 regenerants analysed cytologically, 302 (81.2%) had the expected diploid chromosome number (2n = 2x = 14), 65 (17.5%) were tetraploid (2n = 4x = 28); several aneuploids and mixoploids were also observed. All diploid and tetraploid regenerants were male and female fertile. However, a great variation of female fertility within and between both groups of regenerants was observed.

Karyological characterization of sugar beet gynogenetic lines cultured in vitro

75%

Svirshchevskaya A., Dolezel J.

Journal of Applied Genetics

2001

vol. 42

issue 1

21-32

Flow cytometry was used to screen ploidy levels in 47 cultured in vitro sugar beet gynogenetic lines of various origin and age, obtained after plant regeneration from unfertilized ovules. When donor plants were diploid, the majority of regenerants were found to have cells with 1C, 2C and 4C relative DNA content (mainly haploid and diploid) and there were large differences in the rate of spontaneous in vitro chromosome doubling between individual homozygous lines. Six ovule-derived lines regenerated from fertile and sterile diploid donors of forty-five lines were solid diploids from the very early stages of their in vitro cultivation, and thus could not be classified as doubled haploids. In the case of tetraploid donor plants, the gynogenetic regenerants demonstrated 2x-ploidy level. The results obtained in chimeric plants with both haploid and diploid cells indicated the possibility to overcome mixoploidy by their re-cultivation through generative shoot tip culture. The flow cytometry method confirmed data obtained by conventional microscopic chromosome counting in dividing leaf cells and was found very useful for screening of a large number of regenerants and for characterizing the process of in vitro gynogenetic lines formation in sugar beet.

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2 Journal of Applied Genetics

1 2001

1 1998

1 Dolezel J.

1 Rybczynski J. J.

1 Svirshchevskaya A.

1 Zwierzykowski Z.

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Plant regeneration from immature inflorescence-derived callus of Italian ryegrass (Lolium multiflorum Lam.): chromosome number and fertility of regenerated plants

Karyological characterization of sugar beet gynogenetic lines cultured in vitro