Cyanogenesis variation in the Turnera sidoides L. polyploid complex (Turneraceae, Leiocarpae).

NEFFA, V. S.; FALOCI, M.; JOSE GUILLERMO SEIJO

BOTANICAL JOURNAL OF THE LINNEAN SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2003 vol. 141 p. 85 - 94

0024-4074

This study constitutes the first investigation of cyanogenesis variation within Turnera sidoides autopolyploid complex. The qualitative and quantitative analysis carried out in 39 populations showed that the five subspecies of the complex are cyanogenetic, although the levels of cyanide released varied both among and within subspecies. Among the subspecies, carnea, holosericea and integrifolia showed higher values of HCN released than subspecies pinnatifida and sidoides. Within subspecies, there is a tendency toward an increment of mean cyanide values with ploidy levels and different hypotheses are considered in order to explain this variation. The study of cyanogenesis in populations from different geographical areas cultivated under uniform greenhouse conditions showed that, in the widespread subsp. pinnatifida, HCN variation may also be reflecting the action of different selection pressures, since populations having dissimilar cyanide levels grow in different phytogeographic provinces with different climatic regimes. On the other hand, the fact that the variation of HCN released was greater among populations from different geographical areas than that observed among diploid and tetraploid populations of the same area provides additional evidences for the multiple origins of polyploids of the T. sidoides complex.