Floral biology and the effects of plant-pollinator interaction on pollination intensity, fruit and seed set in Solanum

Reproductive biology and patterns of plant-pollinator interaction are fundamental to gene flow, diversity and evolutionary success of plants. Consequently, we examined the magnitude of insect-plant interaction based on the dynamics of breeding systems and floral biology and their effects on pollination intensity, fruit and seed set. Field and laboratory experiments covering stigma receptivity, anthesis, pollen shed, load and viability, pollinator watch vis-à-vis controlled self, cross and pollinator-exclusion experiments were performed on nine taxa of Solanum: Solanum aethiopicum L., Solanum anguivi Lam., Solanum gilo Raddi, Solanum erianthum Don, Solanum torvum SW, Solanum melongena L. (‘Melongena’ and ‘Golden’) and Solanum scabrum Mill. (‘Scabrum’ and ‘Erectum’). Pollen shed commenced 30 min before flower opening attaining peak at 20 to 30 min and continued until closure. Stigma was receptive 15 to 30 min before pollen release, making most species primary inbreeders (100% selfed) but facultatively outbreeding (12.5 to 75%) through insect pollinators such as Megachile latimanus, Diplolepis rosae and Bombus pennsylvanicus. S. scabrum ‘Scabrum’ was an obligate inbreeder, while S. scabrum ‘Erectum’ was facultatively outbreeding (12.5%). S. melongena ‘Melongena’ was strongly outcrossing (75%) than its relative ‘Golden’ (25%). Small pollen and anther assured high pollen load and pollination efficiency and vice versa, except S. torvum. Diploid species (2n = 24) received crossed pollen (25 to 53.9%) from related species than the tetraploid S. scabrum (2n = 48; 0 to 11%). We concluded that insect-pollinators complement self pollination in Solanum. They provide cross-pollen, which enhanced gene exchange and hybrids in natural population and lower inbreeding depression.Key words: Breeding system, hybridization, insect pollinator, outcrossing, pollination, Solanum

Phytochemical constituents and antioxidant activities of aqueous and methanol stem extracts of Costus afer Ker Gawl. (Costaceae)

Medicinal plants contain bioactive compounds capable of preventing and fighting oxidative related diseases. These compounds must be screened and assayed before effective drugs are developed. Thus, phytochemical constituents and antioxidant activities of aqueous and methanol stem extracts of Costus afer Ker-Gawl were evaluated. C. afer contained flavonoids, phenols, anthraquinones, cardiac glycosides, terpenoids, alkaloids and tannins. Preliminary screening of free radical scavenging activity of extracts with 2,2-Diphenyl-1-picrylhydrazyl (DPPH) using thin layer chromatography tested positive. The aqueous extract had a higher free radical scavenging activity with IC50 (concentration of samples required for 50% inhibition of DPPH radical activity) value of 64.42 g/ml than methanol extract (92.33 g/ml). Furthermore, total phenolic content in aqueous extract (0.66 ± 0.02 mg gallic acid equivalent/g) was significantly higher (p < 0.05) than methanol extract (0.52 ± 0.01 mg gallic acid equivalent/g). In addition, inhibition of lipid peroxidation by aqueous extract (80.60 ± 0.28%) was significantly higher (p < 0.05) than methanol extract (77.00 ± 0.84%). Nevertheless, methanol and aqueous extracts of C. afer possess anti-oxidative properties as well as bioactive metabolites. Thus, stem extracts of C. afer could serve as sources of antioxidants and bioactive compounds for nutrition and therapeutic purposes.Key words: Costus afer, phytochemicals, antioxidant, phenol, nutrition, therapeutic

Cultivars of Codiaeum variegatum (L.) Blume (Euphorbiaceae) show variability in phytochemical and cytological characteristics

In the course of their evolution, plant developed chemical defences when attacked. These phytochemicals inadvertently protect humans against pathogens as antimicrobial medicines. Thus, six clone cultivars of Codiaeum variegatum (Spirale, Royal, Broad Spotted Guinea, Punctatum, Sunray and Royal-like) were chemically and cytologically investigated to evaluate their therapeutic potentials, values and variability. The shoots were relatively rich in alkaloids, cardiac glycosides, saponins, tannins, cardenolides, steroids, and phyllates. Flavonoids, phlobatannins, phenols and anthraquinoneswere sparingly present. Anthraquinones and cardenolides were absent in ‘Spirale’ while ‘Sunray’ lacked tannins, phlobatannins and phenols. Terpenes were found only in ‘Sunray’. Overall, alkaloids were themost abundant with the highest mean value of 1.46% in ‘Royal’ while flavonoids and anthraquinones were trace, 0.002 and 0.003%, in ‘Sunray’ and ‘Royal-like’. Five pigments, carotene (yellow-orange),phaeophytin (grey), chlorophyll a (blue-green) and b (green), and xanthophyll (yellow) were determined. ‘Spirale’, ‘Royal’, ‘Broad Spotted Guinea’ and ‘Punctatum’ had diploid chromosme number of 2n = 60while ‘Sunray’ and ‘Royal-like’ possessed 2n = 30 and 24 respectively. ‘Spirale’ and ‘Sunray’ appeared to have reasonably diverged from the rest. Genetic mutation and chromosomes variability couldaccount for the wide morphological variation and morphotypes in this plant species

Phenotypic variation of F1 and F2 populations from three species of Solanum L. (Solanaceae)

Emerging chromosome types in some Solanum species underscore inherent potentials and possible>new and expanded genome. Interspecific crosses involving the varieties of Solanum melongena L.,Solanum macrocarpon L. and Solanum aethiopicum L. were carried out to assess species phylogenetic relationships and the extent of evolutionary changes with a view to improving the agronomic characters in the hybrids. The dimensions of leaves, petals and fruits in the F1 hybrids were intermediate in values between parents while parental influence was significant in such characters as growth habit, inflorescence types and colour of flowers. Pollen viability was depressed from 97.3 – 71% in parents to 56.8 - 48.8% in the F1 and consistently lowered from 48.6 – 38.2% in the F2 hybrids but restored (63.8%) in an F2 plant. Fruits were few on inflorescence, small sized with generally fewer seeds in the F1 (67 - 132) and F2 (52 – 135) hybrids compared with the parents (87 – 384). A single flowered inflorescence from a cross (S. melongena ‘Melongena’ x S. aethiopicum) revealed a novel gene and possible selective ecological advantage over other hybrids. The incomplete restoration of some of the masked characters in the F2 hybrids suggests a near-complete homogenization of parental genomes and/or chromosomal disharmony through silent genomic changes. These might have prevented sufficient chromosomal rearrangement and full homology for improved vigour in many of the F2 hybrids

Characterization of interspecific hybrids and backcross generations from crosses between twocultivated eggplants (Solanum melongena and S. aethiopicum Kumba group) and implications for eggplant breeding

Common (Solanum melongena L.) and scarlet (S. aethiopicum L.) eggplants are cultivated for their fruits and form part of the same genepool. We have studied plant and fruit characteristics, pollen viability and seed set, phenolics content, and fruit flesh browning in accessions of S. melongena and S. aethiopicum Kumba group, as well as interspecific hybrids between these species and first backcross generations to each parental species. Respective genotypes were also characterized with seven polymorphic SSR markers. The results demonstrate that many differences exist for plant and fruit morphology among S. melongena, S. aethiopicum and the interspecific hybrids. The latter are very vigorous and generally intermediate between the two parents, except for fruit size which is smaller (and parthenocarpic due to a high pollen sterility) than those of any of the parents. Backcross progenies also exhibited morphological variation with moderate heritability values for the attributes evaluated. Variation for fruit size was present in the backcross generations but fruits were small resulting in little variation for fruit shape. Backcross plants with moderate fertility produced seeded fruits. Primary hybrids had fruit phenolics content similar to that of S. aethiopicum, the parent with lowest phenolics concentration, and were heterotic for fruit flesh browning. Backcross progenies were quite variable for both traits. SSR markers did not reveal segregation distortion in the backcross generations for these interspecific hybrids. The results demonstrate that generations derived from sexual interspecific hybridization can be a powerful tool for S. melongena and S. aethiopicum Kumba group breeding. © 2012 Springer Science+Business Media B.V.This work was partially financed by the Ministerio de Ciencia y Tecnologia (AGL2009-07257 and RF-2008-00008-00-00).Prohens Tomás, J.; Plazas Ávila, MDLO.; Raigón Jiménez, MD.; Seguí-Simarro, JM.; Stommel, JR.; Vilanova Navarro, S. (2012). Characterization of interspecific hybrids and backcross generations from crosses between twocultivated eggplants (Solanum melongena and S. aethiopicum Kumba group) and implications for eggplant breeding. Euphytica. 186(2):517-538. doi:10.1007/s10681-012-0652-xS517538186