Contributo preliminare alla sistematica di Chamaecytisus hirsutus e Chamaecytisus supinus

Abstract

Chamaecytisus hirsutus and C. supinus: a preliminary report. – Chamaecytisus hirsutus (L.) Link and C. supinus (L.) Link have been described as twostrictly related species, which differ mainly in the form of inflorescence: C. hirsutus has lateral flowers, C. supinus has terminal flowers. Besides, most Floras provide a set of additional differential characters that should permit to di-C. hirsutus and C. supinus.

The author analyses such differential characters and demonstrates that all of them are inconsistent: therefore the inflorescence seems to be the only difference between C. hirsutus and C. supinus.

The inflorescence itself, however, is not a constant character: indeed, it is known that C. supinus may develop vernal latera flowers besides the normal aestival terminal ones.

The geographic distributions of the two inflorescence types are accurately examined (a report of the distributions is given, a list of herbarium specimens is presented in appendix, a point distribution map of the two types is given in figs. 1 and 2); the only differences are the following ones: plants with flowers in leafy racemes (usually identified as C. hirsutus) seem to be absent from Spain and from Southern Poland, and to be unfrequent in Central and Western France; instead, plants with flowers in heads (usually identified as C. supinus) are very unfrequent in the Southern Balcan Peninsula, and are absent from Southern Greece and the Italian Peninsula.

After a discussion of the biological significance of the capitate and lateral inflorescence, and on the basis of in vivo observations, the author argues that probably the same taxonomic unit is present in the whole area, showing some differences in its flowering behaviour; in the largest part of the areal – including the center of distribution of the species – most individuals flower twice, and therefore have been recorded as two different species; a trend toward the capitate inflorescence is remarkable in the North and in the West; instead, in the South and the East the trend is toward lateral flowers (fig. 3).

Further biometrical and biochemical studies on the species are now in progress; more observations in field in different parts of Europe are necessary in order to get conclusive evidence of the identity of these two so-called «species».     

Sacculatane diterpenoids from axenic cultures of the liverwort Fossombronia wondraczekii

Five new sacculatane diterpenoids, 17,18-epoxy-7-sacculaten-12,11-olide, 7,17-sacculatadien-11,12-olide, 11beta,12-epoxy-7,17-sacculatadien-11alpha-ol, 1beta-acetoxy-11beta,12-epoxy-7,17-sacculatadien-11alpha-ol and 1beta,15xi-diacetoxy-11,12-epoxy-8(12),9(11),17-sacculatatriene along with sacculatal and sacculatanolide have been isolated from axenic cultures of the liverwort Fossombronia wondraczekii and their structures assigned on the basis of their spectroscopical properties.     

Feeding of [5,5-2H(2)]-1-desoxy-D-xylulose and [4,4,6,6,6-2H(5)]-mevalolactone to a geosmin-producing Streptomyces sp. and Fossombronia pusilla

The biosynthesis of the trisnor sesquiterpenoid geosmin (4,8a-dimethyl-octahydro-naphthalen-4a-ol) (1) was investigated by feeding labeled [5,5-2H(2)]-1-desoxy-D-xylulose (11), [4,4,6,6,6-(2)H(5)]-mevalolactone (7) and [2,2-2H(2)]-mevalolactone (9) to Streptomyces sp. JP95 and the liverwort Fossombronia pusilla. The micro-organism produced geosmin via the 1-desoxy-D-xylulose pathway, whereas the liverwort exclusively utilized mevalolactone for terpenoid biosynthesis. Analysis of the labeling pattern in the resulting isotopomers of geosmin (1) by mass spectroscopy (EI/MS) revealed that geosmin is synthesized in both organisms by cyclization of farnesyl diphosphate to a germacradiene-type intermediate 4. Further transformations en route to geosmin (1) involve an oxidative dealkylation of an i-propyl substituent, 1,2-reduction of a resulting conjugated diene, and bicyclization of a germacatriene intermediate 13. The transformations largely resemble the biosynthesis of dehydrogeosmin (2) in cactus flowers but differ with respect to the regioselectivity of the side chain dealkylation and 1,2-reduction