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As a result of its domestication, breeding and subsequent commercialization, African violet (Saintpaulia ionantha H. Wendl.) has become the most famous and popular Saintpaulia species. There is interest in producing cultivars that have increased resistance to pests and low temperature, in the introduction of novel horticultural characteristics such as leaf shape, flower colour, size and form, and in improved productivity and enhanced flower duration in planta. In African violet, techniques such as the application of chemical mutagens (ethylmethanesulfonate, N-nitroso-N-methylurea), radiation (gamma (γ)-rays, X-rays, carbon ion beams) and colchicine have been successfully applied to induce mutants. Among these techniques, γ radiation and colchicine have been the most commonly applied mutagens. This review offers a short synthesis of the advances made in African violet breeding, including studies on mutation and somaclonal variation caused by physical and chemical factors, as well as transgenic strategies using Agrobacterium-mediated transformation and particle bombardment. In African violet, Agrobacterium-mediated transformation is affected by the Agrobacterium strain, selection marker, and cutting-induced wounding stress. Somaclonal variation, which arises in tissue cultures, can be problematic in maintaining true-to-type clonal material, but may be a useful tool for obtaining variation in flower colour. The only transgenic African violet plants generated to date with horticulturally useful traits are tolerant to boron (heavy metal) stress, or bear a glucanase-chitinase gene.

Resumen Las “violetas africanas” Saintpaulia ionantha H. Wendl. (Gesneriaceae) son plantas ornamentales muy valoradas en el mundo por su belleza y capacidad de dar flores durante todo el ano. Esto ha conllevado a que su demanda sea mayor, pues es idonea para decorar espacios interiores del hogar. Por ello, su cultivo con fines comerciales ha aumentado, siendo la propagacion in vitro y su posterior aclimatacion una buena alternativa de emprendimiento en floricultura. Sin embargo, ante escasa informacion referida a la aclimatacion ex vitro de S. ionantha , se propuso como objetivo estandarizar un protocolo de aclimatacion. Para ello, se seleccionaron plantulas in vitro del Laboratorio de Biotecnologia del Instituto de la Papa y Cultivos Andinos, las cuales fueron transportadas al invernadero para su siembra, empleandose diferentes sustratos, constituidos por: T1 = arena + musgo + humus; T2 = arena + musgo; T3 = arena + humus y T4 = arena. Se encontraron diferencias estadisticamente significativas, siendo el tratamiento T1 el que evidencio un buen porcentaje de plantas aclimatadas, el mayor porcentaje de plantas enraizadas, el mayor numero promedio de hojas, el mayor numero promedio de raices normales, y la mayor longitud y ancho promedio de hoja. Se concluye que el sustrato constituido por arena + musgo + humus es el mas optimo para la aclimatacion ex vitro de S. ionantha . Palabras clave: aclimatacion, plantulas, in vitro , Saintpaulia , “violeta africana”. Abstract “African violets” Saintpaulia ionantha H.Wendl. (Gesneriaceae) are ornamental plants very valued in the world for their beauty and ability to give flowers throughout the year. This has brought an increase in their demand, as they are suitable for decorating interior spaces at home. That is the reason because their cultivation for commercial purposes has increased, and the propagation in vitro and its subsequent acclimation is a good alternative of entrepreneurship in floriculture. However, the scarce information of ex vitro acclimation of S. ionantha leads us to propose a standard acclimation protocol. For this purpose, we selected in vitro seedlings from the Biotechnology Laboratory of the Potato and Andean Crops Institute. They were transported to greenhouse for planting using different substrates consisting of: T1 = sand + moss + humus; T2 = sand + moss; T3= sand + humus and T4 = sand. Statistically significant differences were found, with treatment T1 showing a good percentage of acclimated plants, the biggest percentage of rooted plants, the biggest average number of leaves, the biggest average number of normal roots and the biggest average leaf length and width. It was concluded that the substrate constituted by sand + moss + humus is the most optimal for ex vitro acclimation of S. ionantha . Keywords: acclimation, seedlings, in vitro, Saintpaulia ; “african violet”.

Within the family Gesneriaceae, the two related genera Saintpaulia and Streptocarpus contain species that are used as ornamental potted plants. Crosses within the genus Streptocarpus subgenus Streptocarpella and between Streptocarpus and Saintpaulia ionantha were carried out to produce new ornamental plants. Crossing barriers were localised, and methods to overcome these barriers were tested. The in vitro germination ability of pollen was determined; germination varied from 3 to 85% among genotypes. A high correlation coefficient of 0.99 was found between the assessment of pollen viability using staining with 2,5-diphenyl tetrazolium bromide (MTT) and in vitro germination. From crosses of nine Streptocarpus species from the subgenus Streptocarpella, 11 hybrids were established. Hybridity was confirmed in five of these crosses by morphological and RAPD (random amplified polymorphic DNA) marker analysis. An embryo rescue technique was used in an attempt to overcome existing post-zygotic barriers in intergeneric crosses between S. ionantha and Streptocarpus species. Despite swelling of the ovules, which is usually considered as an indicator for successful fertilisation, no germination of plants from embryos was observed with this method.

The Gesneriaceae (Lamiales) is a family of flowering plants comprising >3000 species of mainly tropical origin, the most familiar of which is the cultivated African violet ( Saintpaulia spp.). Species of Gesneriaceae are poorly represented in the lists of taxa sampled for genome size estimation; measurements are available for three species of Ramonda and one each of Haberlea , Saintpaulia, and Streptocarpus , all species of Old World origin. We report here nuclear genome size estimates for 10 species of Sinningia , a neotropical genus largely restricted to Brazil. Flow cytometry of leaf cell nuclei showed that holoploid genome size in Sinningia is very small (approximately two times the size of the Arabidopsis genome), and is small compared to the other six species of Gesneriaceae with genome size estimates. We also documented intraspecific genome size variation of 21%–26% within a group of wild Sinningia speciosa (Lodd.) Hiern collections. In addition, we analyzed 1210 genome survey sequences from S. speciosa to characterize basic features of the nuclear genome such as guanine–cytosine content, types of repetitive elements, numbers of protein-coding sequences, and sequences unique to S. speciosa. We included several other angiosperm species as genome size standards, one of which was the snapdragon ( Antirrhinum majus L.; Veronicaceae, Lamiales). Multiple measurements on three accessions indicated that the genome size of A. majus is ∼633 × 106 base pairs, which is approximately 40% of the previously published estimate.

Saintpaulia (H. Wendl.) is a forest-dependent, endangered plant genus endemic to Tanzania and Kenya. The taxonomy of Saintpaulia from the Usambara Mountains and adjacent lowlands in north-eastern Tanzania is problematic because of the morphological similarity of the species and the presence of considerable intraspecific variation. Conventional molecular phylogenetic methods have failed to reveal the genetic structure of this Saintpaulia complex. In this study, we assessed the genetic composition of 12 Saintpaulia populations, representing four different morphotypes, from the East Usambara Mountains using inter-simple sequence repeat (ISSR) markers. Relatively high genetic diversities were observed within populations (mean h = 0.320), indicating their adaptive potential. Little genetic differentiation amongst populations (mean Fst = 0.063) and the genetic divergence of the rosulate and trailing morphotypes support the hypothesis of ongoing divergent evolution within the East Usambara metapopulation(s) of Saintpaulia. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157, 347–355.

Hypersensitivity is induced in many species of Acanthaceae and Gesneriaceae by local mechanical wounding. Once a plant of these species sustains a wounded leaf, it exhibits a temporary hypersensitive state and severe injury easily occurrs even in unwounded leaves. Locally wounded African violet (Saintpaulia sp.) plants sometimes show severe injury even at a noninjurious temperature for this species. This study was aimed to clarify changes in the temperature sensitivity of hypersensitivity-induced African violet plants by local wounding. The basal leaves of African violet ‘Ritali’ plants were cut as a local wounding treatment. The locally wounded plants were transferred to growth chambers at various temperatures and we evaluated the degree of leaf injury using an analysis software. In locally wounded plants, temperature sensitivity increased and leaf injury was observed even at 11°C, which is a noninjurious temperature for unwounded African violet. Such a wound-induced sensitivity to low temperature treatment (7°C for 1 h) quantitatively increased with local wounding severity. For the investigation of time-course changes in the hypersensitive state (wounding memory) of locally wounded plants, the plants were transferred to low temperature conditions at various intervals after the wounding treatment. The wounding memory was short-lived, that is, it was generally observed immediately after local wounding and then almost disappeared 30 min after. In conclusion, the low temperature sensitivity of African violet plants was enhanced by prewounding treatment.

Summary A synopsis of the poorly known genus Linnaeopsis , endemic to the Uluguru Mts. in Tanzania, is provided. Three species are recognized: L. subscandens B. L. B urtt , L. heckmanniana E ngl . and L. alba (E. A. B ruce ) B. L. B urtt . L. heckmanniana is subdivided into two subspecies, ssp. heckmanniana and ssp. gracilis (E. A. B ruce ) W eigend , stat. nov., and also in L. alba two subspecies are distinguished, ssp. alba and ssp. edwardsii W eigend , subsp. nov. The latter is marked by rugose leaves with 5-to 6-celled trichomes on the adaxial side (vs. 3- to 4-celled hairs in ssp. alba ) and by different hair cover of the ovary and stem. The affinities of Linnaeopsis are discussed and an origin within or near Streptocarpus subg. Streptocarpus suggested. A close relationship with Saintpaulia appears rather unlikely.

Summary. Two new endemic species of Saintpaulia, S. ulugurensis Haston and S. watkinsii Haston (Gesneriaceae) are described from the Uluguru Mountains. Their discovery emphasises the need for additional floristic work to be carried out in this area and supports the calls for strong conservation measures for the fragile forest habitats of Tanzania.

Floral diversity in Streptocarpus and Saintpaulia can be classified into six distinct types on the basis of quantitative variation. Species are differentiated by overall flower size and by corolla lobe size in relation to corolla tube opening size, characteristics implicated in pollination ecology. Saintpaulia has a very short corolla tube and yellow protruding anthers, strikingly different from Streptocarpus , and probably associated with buzz pollination. Some species of Streptocarpus and all species of Saintpaulia are enantiostylous, a feature often linked to buzz pollination. Mapping of these floral characters onto a molecular phylogeny based on ITS sequence data showed that inStreptocarpus flower size evolved from small to large, with reversals in four species. The putatively bee pollinated ‘open-tubed’ type had two independent origins, and the putatively lepidopteran-pollinated ‘keyhole’ type had four separate origins. Enantiostyly had one or two origins. The degree of zygomorphy varies withinStreptocarpus/Saintpaulia. The most extreme difference is between Saintpaulia ionantha and aSaintpaulia peloric cultivar. The developmental basis of floral variation was compared using SEM in three very different types: Streptocarpus primulifolius, Saintpaulia ionantha and a Saintpaulia peloric cultivar. Differences in corolla tube length and zygomorphy are established very early in flower development. Small, early changes in flower development establish major changes in mature floral morphology.

vegetative structures among some species, and are among the few genera in the Gesneriaceac which include species with chromosome counts or 1/ = 15. The similarity of these features has indicated that the two genera are likely to be closely related. This study examines the sequences of the chloroplast gene ndhF among several representative species of SaiJJlpulIlia and representatives of Slreptocarpu.I' subgenera Strcplocarpella and StreptocarplI.l'. The results of this analysis are congruent with those of a previous analysis based on the nuclear ribosomal region, ITS. Sailltpalliia was found to be nested within Streptocarpll.l' subgenus Streprocarpella. The results raise the possibility of the taxonomic revision or these genera, and this is discussed. Comparisons between the data sets are made regarding utility of the two regions, sample size and outgroup.

Saintpaulia (Gesneriaceae) is confined in the wild to small patches of forest in East Africa (Tanzania and Kenya), with most of the species occurring in submontane or montane forest. However, a few species are known from lowland forests and this paper outlines the distribution and ecology of some of the species recorded from lowland sites. Additional sites for S. confusa B.L. Burtt, S. diplotricha B.L. Burtt, S. grotei Engl., S. ionantha H. Wendl, S. tongwensis B.L. Burtt and two, possibly new, species, have been located during recent field studies. One of the critically endangered species, S. tongwensis has featured previously in Curtis's Botanical Magazine (N.S. t. 11) and its illustration and description are repeated here.

The molecular phylogeny of African violets (Saintpaulia H. Wendl.), based on ribosomal DNA internal transcribed spacer (ITS) sequences, follows the disjunct biogeography of the genus. Sequence analysis by parsimony of 19 accessions, representing 17 currently recognized Saintpaulia species, resulted in four trees of 182 steps. The first major division is between S. goetzeana, from the Uluguru Mts, Tanzania, and the rest of the genus. The basal position of S. goetzeana, and its putative primitive characters, may indicate an Uluguru origin for Saintpaulia and subsequent colonization of the more northerly mountains. Of the remainder, S. teitensis, from the Teita Hills of Kenya, is sister taxon to the other species (which occur mainly in the Usambara Mts of north-east Tanzania). A group of nine Usambaran species that we call the 'ionantha complex' show minimal ITS genetic differentiation and are also taxonomically critical. Species diversity in the Usambara Mts appears to be the result of rapid, recent (possibly Pleistocene) radiation. This study reveals the limitations of ITS sequences for elucidating the radiation of poorly differentiated species (the ionantha complex). However, the molecular data strongly suggest that conservation of the Uluguru and Teita populations is essential for the protection of the full range of diversity within the genus.

Saintpaulia ionantha H. WENDL. Salzburg: Flachgau, Mattsee, Friedhof, auf Kies verwildert, ca. 505m, 8044/2, Sommer 2003, vid. CS & OS. Neu für Österreich. Die bei uns als "Usambaraveilchen" bekannte Gattung Saintpaulia gehört nicht zu den Violaceen, sondern zu den Gesneriaceen. Sie umfasst 20 Arten niedriger, immergrüner Stauden, die in einer begrenzten Region des tropischen Ostafrikas auf Böschungen, an Flussufern oder als Epiphyten auf Bäumen auftreten. Saintpaulia ionantha bildet dabei für die meisten der ca. 2000 bekannten, verschiedenfarben blühenden Kultivare den Ausgangspunkt (BARTHLOTT 2000). Obwohl als nicht frosthart beschrieben, wird die Art bei uns selten im Freiland kultiviert, so zum Beispiel auf Friedhöfen. Von solchen Kulturen stammt auch die hier beobachtete, sicherlich vorübergehende Verwilderung ab. Aus Österreich waren bislang noch keine entsprechenden Nachweise bekannt (vgl. WALTER et al. 2002) und auch für Mitteleuropa dürfte die Art neu sein (vgl. z.B. PYŠEK et al. 2002, GASSMANN & WEBER 2006)., Published as part of Stöhr, O., Pilsl, P., Essl, F., Hohla, M. & Schröck, C., 2007, Beiträge zur Flora von Österreich, II, pp. 155-292 in Linzer biologische Beiträge 39 (1) on page 243, DOI: 10.5281/zenodo.5407540, {"references":["BARTHLOTT W. (Hrsg.) (2000): DuMont`s grosse Pflanzenenzyklopadie von A-Z. - 3. Aufl., DuMont, Koln.","WALTER J., ESSL F., NIKLFELD H. & M. A. FISCHER (2002): Gefasspflanzen. - In: ESSL F. & W. RABITSCH (Hrsg.): Neobiota in Osterreich. - Umweltbundesamt, Wien: 46 - 173.","PYSEK P., SADLO J. & B. MANDAK (2002): Catalogue of alien plants of the Czech Republic. - Preslia 74: 97 - 186."]}

African Violets, genus Saintpaulia, (Gesneriaceae), are endemic to coastal Kenya and northern Tanzania. The taxonomic status of the wild species of the African Violet remains unresolved. In addition, there is an almost complete lack of knowledge about the genetic variation among natural populations of the African Violets. We have embarked on a project to assess the chloroplast DNA variation among these African Violets, with special emphasis on the only four remaining natural populations of Saintpaulia rupicola B.L. Burtt and Saintpaulia sp. nov. from Coastal Kenya.

Recent phylogenetic studies have shown that Colpogyne, Hovanella, Linnaeopsis, Saintpaulia and Schizoboea (Gesneriaceae) are embedded in Streptocarpus . Saintpaulia had been expanded to over 20 species, but this narrow species concept was challenged by recent studies that showed that most of these taxa were poorly genetically and morphologically differentiated. The number of species in Saintpaulia has been reduced to six, with the majority of former species reduced to subspecies and varieties of S. ionantha. A key to the species in Streptocarpus subgenus Streptocarpella in tropical East Africa, and new combinations in Streptocarpus are provided here.

The Fantasy mutation in Saintpaulia ionantha produced flowers that had a purple background color with pink sectors. The purple background tissue contained kaempferol 3- O -glucoside and malvidin 3-rutinoside-5-glucoside. The pink sector tissue contained kaempferol 3- O -glucoside and peonidin-3-rutinoside-5-glucoside.