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At least 505 records · Page 28Linked to original sources
PubMed2005

In vitro regeneration of Hagenia abyssinica (Bruce) J.F. Gmel. (Rosaceae) from leaf explants.

A protocol for shoot regeneration of Hagenia abyssinica (Bruce) J.F. Gmel. has been developed using leaf explants originating from in vitro seedlings and mature material. The explants were cultured on Murashige and Skoog medium containing various concentrations of alpha-naphthaleneacetic acid and thidiazuron (TDZ). Concentrations of TDZ lower than 1.0 microM promoted direct shoot regeneration, but higher concentrations promoted callus induction. Around 96-100% regeneration was obtained between 1.0 and 10 microM TDZ. The average number of shoots per explant at 1.0 microM TDZ was 8.4+/-4.8. Among the different explants used, the highest percentage of regeneration and shoots per explant was obtained from complete leaf explants. A significant (P< or =0.05) difference in regeneration capacity was observed among the five genotypes examined. The resulting shoots were multiplied on multiplication medium, rooted and acclimatised in a greenhouse.

Agriculture↗
PubMed2002

Trends in site-number change of rDNA loci during polyploid evolution in Sanguisorba (Rosaceae).

To elucidate the evolutionary dynamics of rDNA site number in polyploid plants, we determined 5S and 18S-5.8S-26S rDNA sites for ten species of Sanguisorba (2n=14, 28, 56) and a single species of each of three outgroup genera, Agrimonia (2n=28), Rosa (2n=14), and Rubus (2n=14) by the fluorescence in situ hybridization (FISH) method. We also estimated phylogenetic relationships among these species using matK chloroplast DNA (cpDNA) sequences, and reconstructed the evolutionary history of rDNA site number based on the maximum parsimony method. The 2n=14 and 2n=28 plants of all genera except Rosa carried two 5S rDNA sites, whereas Rosa and 2n=56 plants carried four sites. The 2n=14 plants had two 18S-5.8S-26S rDNA sites, whereas Sanguisorba annua and 2n=28 plants had four or six sites. Phylogenetic analysis showed that polyploidization from 2n=14 to 2n=28 has occurred once or three times in Sanguisorba and Agrimonia. The 5S rDNA sites duplicated during each ancestral polyploidization were evidently lost after each polyploidization. However, the duplicated 18S-5.8S-26S rDNA sites were all conserved after each polyploidization. Thus, the duplicated 5S rDNA sites tend to have been eliminated, whereas those of 18S-5.8S-26S rDNA tend to have been conserved in Sanguisorba. In the most parsimonious hypothesis, 2n=14 in S. annua is a secondary, putatively dysploid state, reduced from 2n=28.

Biological Evolution↗