Change in nuclear DNA content and pollen size with polyploidisation in the sweet potato (Ipomoea batatas, Convolvulaceae) complex.

Genome size evolution and its relationship with pollen grain size has been investigated in sweet potato (Ipomoea batatas), an economically important crop which is closely related to diploid and tetraploid species, assessing the nuclear DNA content of 22 accessions from five Ipomoea species, ten sweet potato varieties and two outgroup taxa. Nuclear DNA amounts were determined using flow cytometry. Pollen grains were studied using scanning and transmission electron microscopy.

Increased resistance to fungal wilts in transgenic eggplant expressing alfalfa glucanase gene.

The wilt diseases caused by Verticillium dahliae and Fusarium oxysporum are the major diseases of eggplant (Solanum melongena L.). In order to generate transgenic resistance against the wilt diseases, Agrobacterium-mediated gene transfer was performed to introduce alfalfa glucanase gene encoding an acidic glucanase into eggplant using neomycin phosphotransferase (npt-II) gene as a plant selection marker.

Effect of genotype, gelling agent, and auxin on the induction of somatic embryogenesis in sweet potato (Ipomoea batatas Lam.).

Lateral buds of six cultivars of sweet potato were induced to form embryogenic callus in a culture medium solidified with two types of gelling agents, Agar or Gelrite, and supplemented with various concentrations of auxins, 2,4-D, 2,4,5-T and Picloram. Of the six cultivars screened, only three gave an embryogenic response. Best results with an average of 3.

ISSR and isozyme characterization of androgenetic dihaploids reveals tetrasomic inheritance in tetraploid somatic hybrids between Solanum melongena and Solanum aethiopicum group Gilo.

Gene exchanges between Solanum melongena and its allied relative Solanum aethiopicum are a crucial prerequisite for introgression of useful traits from the allied species into the cultivated eggplant. In order to evaluate the extent of genetic recombination between the 2 species, biochemical and molecular markers were employed. A dihaploid population obtained through anther culture of the corresponding tetraploid somatic hybrids was genetically analyzed.

Evaluation of somatic hybrids of potato with Solanum stenotomum after a long-term in vitro conservation.

Somatic hybrids of potato with a cultivated relative, Solanum stenotomum also called Solanum tuberosum Stenotomum group, were evaluated for their physiological and agronomical characteristics as well as the stability of the introgressed resistance to bacterial wilt, caused by Ralstonia solanacearum, after a long-term in vitro conservation for more than 5 years. Analysis of photosynthesis showed that the PEPC/Rubisco ratio remained lower than 0.5 for all vitroplants of potato and the somatic hybrids, except for the relative species.

The origin and evolution of sweet potato (Ipomoea batatas Lam.) and its wild relatives through the cytogenetic approaches.

The distribution and organization of 5S and 18S-5.8S-26S (18S) rDNA were studied in 10 varieties of hexaploid Ipomoea batatas, five accessions of tetraploid Ipomeoa trifida, and six related species (five diploids, I. trifida, I.

Production of potato intraspecific somatic hybrids with improved tolerance to PVY and Pythium aphanidermatum.

Somatic hybridization can be an interesting alternative for the selection of heterozygous and vigorous potato plants through combination of dihaploid genomes. The resulting hybrids can harbour interesting characters and thus can be used in agriculture if they are in agreement with agronomic criteria. In this report, we used an intraspecific somatic hybridization technique for the production of tetraploid potato lines.

Amplification of Nicotiana sylvestris mitochondrial subgenomes is under nuclear control and is associated with phenotypic changes.

We have previously shown the presence in a Nicotiana sylvestris protoplast-derived plant of both a nuclear mutation conferring male sterility (ms4) and a mtDNA reorganisation, named U, characterised by the amplification of substoichiometric mtDNA fragments generated by recombination in the parent T mtDNA. Here we show by physical mapping that the recombining repeats are in direct orientation, thus generating two subgenomes both of which are amplified in the U organisation to the detriment of the parent molecule, and are maintained through sexual reproduction. The nuclear ms4 mutation is likely to have play a role in the shift in mitochondrial molecule equilibrium, as higher levels of recombinant fragments were present in protoplast-derived T calli carrying the ms4 allele than in wild type calli or leaves.

Maternal inheritance of a chloroplast microsatellite marker in controlled hybrids between Fraxinus excelsior and Fraxinus angustifolia.

Restriction fragment length polymorphism, polymerase chain reaction-restriction fragment length polymorphism and simple sequence repeat (SSR or microsatellites) analyses were performed to detect chloroplast DNA polymorphisms between two ash species, Fraxinus excelsior and F. angustifolia. Only one SSR locus was found to be polymorphic, confirming the very close relatedness of these species.

Source of resistance against Ralstonia solanacearum in fertile somatic hybrids of eggplant (Solanum melongena L.) with Solanum aethiopicum L.

Solanum aethiopicum is reported to carry resistance to bacterial wilt disease caused by Ralstonia solanacearum, which is one of the most important diseases of eggplant (Solanum melongena). These two species can sexually be crossed but the fertility of their progeny is very low. In order to transfer the resistance and improve the fertility, somatic hybrids between S.

Resistance to bacterial wilt in somatic hybrids between Solanum tuberosum and Solanum phureja.

Somatic hybrid plants were produced after protoplast electrofusion between a dihaploid potato, cv. BF15, and a wild tuber-bearing relative, Solanum phureja, with a view to transferring bacterial wilt resistance into potato lines. A total of ten putative hybrids were selected.

Isozyme modifications and plant regeneration through somatic embryogenesis in sweet potato (Ipomoea batatas (L.) Lam.).

The potential of somatic embryogenesis was evaluated for 10 cultivars of sweet potato through extensive embryogenic response and isozyme analysis. Embryogenic callus was induced by incubating lateral buds on Murashige and Skoog medium containing 10 μM 2,4-dichlorophenoxyacetic acid for 6-8 weeks. The frequency of embryogenic response was low, and varied with genotypes, ranging from 0 to 17%.

Plant regeneration from cultured protoplasts of the cooking banana cv. Bluggoe (Musa spp., ABB group).

Suspensions of embryogenic cells of a triploid banana (Musa spp., cv. Bluggoe) were initiated from the uppermost part of meristematic buds, and used as protoplast source.

Production and characterization of fertile somatic hybrids of eggplant (Solanum melongena L.) with Solanum aethiopicum L.

In order to produce fertile somatic hybrids, mesophyll protoplasts from eggplant were electrofused with those from one of its close related species, Solanum aethiopicum L. Aculeatum group. On the basis of differences in the cultural behavior of the parental and hybrid protoplasts, 35 somatic hybrid plants were recovered from 85 selected calli.

Somatic hybrid plants produced by electrofusion between dihaploid potatoes: BF15 (H1), Aminca (H6) and Cardinal (H3).

In order to regenerate somatic hybrids, mesophyll protoplasts from a dihaploid potato, BF15 (H1), were electrofused with those from two other dihaploid clones, Aminca (H6) and Cardinal (H3). Determination of the ploidy level by flow cytometry showed that 10% of plants regenerated from the fusion experiment with "BF15 + Aminca" were diploids, 14% triploids, 63% tetraploids and very few were mixoploids or had a higher ploidy level. Using morphological markers and vigour in plant growth, we were able to recover a total of 24 somatic hybrid plants, respectively 20 and 4 hybrids (accounting for 12% and 13% of regenerants) from the fusions "BF15 + Aminca" and "BF15 + Cardinal".

Somatic hybrid plants produced by electrofusion between Solanum melongena L. and Solanum torvum Sw.

Somatic hybrid plants between eggplant (Solanum melongena) and Solanum torvum have been produced by the electrofusion of mesophyll protoplasts in a movable multi-electrode fusion chamber. Using hair structure as a selection criteria, we identified a total of 19 somatic hybrids, which represented an overall average of 15.3% of the 124 regenerated plants obtained in the two fusion experiments.

Plant regeneration from protoplast culture of sweet potato (Ipomoea batatas Lam.).

This is the first report on successful plant regeneration from protoplasts of sweet potato. Two cultivars (Guyana and Duclos XI) of sweet potato plants propagated under in vitro conditions were used as the source of protoplasts. Green compact calli with meristematic areas were induced in the medium supplemented with 2mg1(-1) zeatin, and plant regeneration occurred when these calli were transferred onto the medium with zeatin level reduced to 0.