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- Flavonoids in phylloclades discriminate endemic Semele androgyna chemotypes from MadeiraPublication . Ganança, F. T.; Charpentier, J. P.; Carvalho, M. Â. A. Pinheiro de; Thangadurai, D.; Joseph, C.; Franco, E.; Sousa, N.; Wilcock, C.C.; Jay-Allemand, C.; Santos, T. M. M. dosThirty-five randomly-collected Semele androgyna Kunth samples were screened by RP-HPLC for their phenolic composition. Fraction analysis allowed the detection of 17 different compounds. According to their retention times and UV spectra obtained by diode array analysis, these phenolics represent three classes: phenolic acids, flavones and flavonols. Co-chromatography with specific standards enabled identification of quercetin, rutin and quercitrin in Semele tissues for the first time. Polymorphism based on phenolic composition was evaluated using multivariate analysis and showed four distinct S. androgyna clusters. This polymorphism was not associated with morphological diversity or different in ambient light intensities. Biochemical differentiation is thus present in this species. The application of multivariate analysis techniques to RP-HPLC data has allowed the classification of samples into two groups, previously proposed on the basis of morphological and cytotaxonomical information. Therefore, the use of phenolics as chemotaxonomic markers in Semele is highly recommended because of its diagnostic value, even at a subspecies level. Discriminant canonical analysis and Mahalanobis distances confirmed these clusters as recognisable chemosystematic units. However, these units do not support the separation of S. pterygophora.
- Soil conditions and evolution of aluminium resistance among cultivated and wild plant species on the Island of MadeiraPublication . Ganança, J. F. T.; Abreu, I.; Sousa, N. F.; Paz, R. F.; Caldeira, P.; Santos, T. M. M. dos; Costa, G.; Slaski, J. J.; Carvalho, M. Â. A. Pinheiro deSoil samples collected from different soil formations throughout the Island of Madeira were analysed for pH, aluminium (Al) and organic matter content. On average, the Madeira soils appeared to be acid with a mean pH of 5.01, containing 0.79 cmol/kg of ionic Al and 3.02% organic matter, which may create favourable conditions for the development of Al resistance among plant species inhabiting the island. Six plant species were evaluated for their resistance to Al using the erichrome cyanine R tests: three agricultural species including wheat (Triticum aestivum L. and Triticum turgidum L.) and corn (Zea mays L.) and three wild species from the genus Sinapidendron. Profound differences in adaptation to local edaphic parameters (Al content, acidity, organic matter, altitude) between cultivated and wild species were observed. Comparison of the distribution patterns of the cultivated and wild species on the island may indicate that the anthropogenic activities played a pivotal role in the development of enhanced Al resistance among the cultivated species, while edaphic conditions seem to be a secondary factor.
- Palynological study of the endemic woody sonchus fron the flora of Madeira: a morphological and molecular approachPublication . Carvalho, M. A. A. Pinheiro de; Câmara, I. G.; Santos, T. M. M. dos; Correia, R. S.