Floral phenology, seed germination and hybrid plants of the Amerindian yam (Dioscorea trifida)

The Amerindian yam (Dioscorea trifida) is a food plant native to the Amazon region. Several local varieties are cultivated by traditional family farmers for consumption and local trade. However, socioeconomic processes may be causing species genetic erosion. Knowledge about species sexual reproduction is essential for its conservation and genetic improvement. The objective of this study was to observe the floral phenology, to assess the germination and dormancy of seeds, to conduct controlled pollinations and to select hybrid plants of D. trifida with agronomic potential. Seed dormancy was confirmed and was broken by after-ripening at 28 oC and 80% RH. We carried out controlled pollinations between local landraces and cultivated the resulting hybrid plants in the field. The new genotypes showed high phenotypic variability and tubers with new characteristics, which permitted the selection of genotypes with agronomic potential for further studies. The results contribute to the conservation of agrobiodiversity and genetic improvement for added value of Amazonian native food plants. (AU)

Liana species composition differs, in spite of trait similarities, in two adjacent forest types in Central Brazil

Abstract:In the Parana basin, the Serra de Maracaju juxtaposes the Seasonal Dry Forest and the cerradão (a phytophysiognomy of Cerrado), two distinct vegetation types that differ in canopy height, tree density, and composition of the understory. In the same way, these differences may be reflected in the composition of climbing plant species found in these two forest types. Thus, in this study we compared the climbing species in two forest fragments of Serra de Maracaju to understand: (1) Are species richness and floristic composition of climbing plants similar in cerradão and seasonal deciduous forest?, (2) What degree of floristic compositional difference exists between the two vegetation types?, (3) Do the two vegetation types differ significantly in climbing mechanisms, life forms, and dispersal syndromes represented among climbing species? For this, we established and sampled four plots per forest type over 24 months. Species were identified and each one classified, based on three discrete traits. Proportional differences were analyzed using chi-square tests. Our results showed that species richness and floristic composition of climbing plants in the cerradão and the seasonal deciduous forest were not similar. Climber species richness in cerradão was 37 while in the seasonal deciduous forest it was 31; they share only 13 species. Four families, Dioscoreaceae, Fabaceae, Malpighiaceae, and Sapindaceae, included over 60 % of the climbing species. The morphological traits most common in both forest types were herbaceous life form, apical twining mechanism, and wind dispersal. Dioscoreaceae was found to be the dominant family, but is the first time to be reported for this condition in Brazil. Bignoniaceae and Passifloraceae ocurred only in the cerradão, and Asteraceae and Combretaceae in the seasonal deciduous forest; some species were found exclusively in a type of forest. Floristic composition of the cerradão and seasonal deciduous forest fragments were substantially different, in spite of physical proximity. However, their climbing species are not statistically distinct in morphological characteristics, possibly due to uniform climatic conditions and the similarity of species because of a shared ancestry (similar families). Rev. Biol. Trop. 65 (3): 1215-1225. Epub 2017 September 01.

Resumen:La Serra de Maracaju yuxtapone los distintos tipos de vegetación de la floresta seca estacional y del cerradón (la fitofisiognomía del cerrado). Los dos tipos de vegetación son distintos en altura de copa, densidad de árboles y composición del sotobosque. Estas diferencias deben reflejarse en la composición de especies de plantas trepadoras que se encuentran en los dos tipos de bosque. Especies trepadoras de dos fragmentos forestales de la Serra de Maracaju han sido comparadas para responder: (1) ¿La riqueza de especies y composición florística de trepadoras es similar en el cerradón y en la floresta estacional decidua? (2) ¿Cuáles especies distinguen los dos tipos vegetacionales de otros? (3) ¿Los dos tipos vegetacionales difieren significativamente en mecanismo de ascensión, formas de vida y síndrome de dispersión en las especies trepadoras? Cuatro parcelas por tipo de floresta han sido muestreadas durante 24 meses. Las especies fueron identificadas y caracterizadas en tres rasgos discretos. Las diferencias proporcionales fueron analizadas usando el test chi-cuadrado. La riqueza y composición florística de trepadoras no fue similar en las dos formaciones: 37 especies en el cerradón y 31 en la floresta estacional decidua, con 13 especies compartidas. Dioscoreaceae, Fabaceae, Malpighiaceae y Sapindaceae corresponden al 60 % de las especies trepadoras. Las formaciones poseen características comunes como la forma de vida herbácea, el mecanismo de ascensión voluble y la anemocoria. La familia predominante fue Dioscoreaceae, no prevalente en estudios en Brasil. A pesar de la proximidad geográfica, la composición florística de los fragmentos de cerradón y de la floresta estacional decidua difiere substancialmente. Las características morfológicas de las especies no difieren estadísticamente, posiblemente por las condiciones climáticas uniformes y la fuerte similitud entre las composiciones florísticas de las familias.

Total saponins from dioscorea septemloba thunb reduce serum uric acid levels in rats with hyperuricemia through OATP1A1 up-regulation / 华中科技大学学报（医学）（英德文版）

The aim of this study is to evaluate the efficacy of total saponins of Dioscorea (TSD), an extract of the Chinese herbal Bi Xie, on hyperuricemia and to elucidate the underlying mechanisms. The rat hyperuricemia model was established by administration of adenine. Thirty-two rats were randomly allocated into 4 groups: model group, low/high-dose TSD-treated groups, and allopurinol-treated group. Meanwhile, 8 rats were used as normal controls. Serum uric acid (UA), blood urea nitrogen (BUN), serum creatinine (Scr), and organic anion transporting polypeptide 1A1 (OATP1A1) levels were measured. Comparison between the model group and treatment (allopurinol and TSD) groups showed the serum UA levels were significantly decreased in treatment groups. TSD had similar effects to allopurinol. It was found that the OATP1A1 protein expression levels in treatment groups were higher than in model group and normal controls. And different from the allopurinol-treated groups, TSD-treated group had elevated OATP1A1 expression levels in the stomach, liver, small intestine and large intestine tissues. It was suggested that TSD may facilitate the excretion of UA and lower UA levels by up-regulating OATP1A1 expression.

Efficiency of RAPD, ISSR, AFLP and ISTR markers for the detection of polymorphisms and genetic relationships in camote de cerro (Dioscorea spp. )

Background At present, species known as camote de cerro (Dioscorea spp.) are found only in the wilderness in Mexico, but their populations are extremely depleted because they are indiscriminately collected, it is urgent to evaluate the conservation status of these plants in order to design conservation genetics programs. In this study, genetic diversity parameters along with cluster analysis based on Jaccard's coefficient were estimated with the objective to assess the efficiency of Random Amplified Polymorphic DNA (RAPD), Inter Simple Sequence Repeat (ISSR), Amplified Fragment Length Polymorphism (AFLP) and Inverse Sequence Tagged Repeat (ISTR) molecular DNA markers in the Dioscorea genus. Results The polymorphic information contents were quite similar for all markers (≈0.48). Genetic variation of Dioscorea spp., in terms of average heterozygosity was lower with ISTR (0.36), and higher when other markers were used (RAPD = 0.43; ISSR = 0.45 and AFLP = 0.47). Conclusion This indicates an important level of genetic differences despite the fact that the plant is asexually propagated. Based on the diversity statistics, any marker tested in present work can be recommended for use in large-scale genetic studies of populations. However, the low correlations among different molecular marker systems show the importance of the complementarity of the information that is generated by different markers for genetic studies involving estimation of polymorphism and relationships.

Two new steroidal saponins from the rhizomes of Dioscorea zingiberensis / 中国天然药物

AIM@#To investigate the chemical constituents of Dioscorea zingiberensis C. H. Wright.@*METHODS@#The compounds were isolated by various chromatographic techniques, and the structures of the new steroidal saponins were elucidated by extensive 1D- and 2D-NMR, MS, and IR spectral analysis.@*RESULTS@#The 70% EtOH extract of the rhizomes of Dioscorea zingiberensis afforded two new steroidal saponins, zingiberenosides A (1) and B (2), along with eight known analogues, 3β, 26-dihydroxy-25(R)-furosta-Δ(5, 20(22))-diene-3-O-α-L- rhamnopyranosyl-(1→2)-O-β-D-glucopyranoside (3), methyl parvifloside (4), deltoside (5), methyl deltoside (6), zingiberensis new saponin (7), deltonin (8), progenin III (9) and diosgenin-diglucoside (10).@*CONCLUSION@#Two new steroidal saponins were isolated from Dioscorea zingiberensis and their structures determined.