Taxonomia, numeros cromossomicos e quimica de especies de Crotalaria L. (Leguminosae-Papilionoideae) no Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Crotalaria L. belongs to the family Leguminosae, subfamily Papilionoideae, tribe Crotalarieae. The genus has 600 species in tropics and subtropics mostly in Africa and India. The infrageneric c1assification was based on floral features of African species, not involving all the morphological amplitude of some American groups. It makes difficult to place the species in these categories. The major aim of the present study was to revise the genus Crotalaria from Brazil and the evaluation of pyrrolizidines alkaloids profiles and chromosome numbers to supplement the sistematic of the genus, especially for the infrageneric c1assification. The thesis consists of five chapters: 1. Taxonomic survey of the genus Crotala ria , inc1uding the update of descriptions, ilustrations and identification key to the infrageneric taxa. In Brazil, there are 31 native and 11 introduced or naturalized species of Crotalaria inserted on the four sections. We described a new species and made seven synonymizations. 2. Considerations about the phytogeography and preferred habitat of the Crotalaria species from Brazil. The species of Crotalaria occurs on the Cerrado, Paranense, Atlântica, Amazônica, Caatinga, Chaquenha, Guayana and Pampeana biogeographical provinces (sensu Cabrera &Willink). The Province of Cerrado presented the major number of restrict species followed by Paranense province. The geographical distribution of species along of the states in the Brazil showed that Minas Gerais and Goiás States have the greatest species diversity. C goiasensis and C. irwinii are endemic to the state of Goiás, C. clausseni to São Paulo, C. rufipila to Minas Gerais and C. brachycarpa and C. harleyi are endemic to Bahia. In contrast, C. micans, C. stipularia, C. maypurensis and C. incana are widely distributed in Brazil. 3. Chromosome numbers are presented for 24 taxa of Crotalaria native to Brazil. Our data are new counts for 14 taxa, but some confirm previous reports or represent numbers, which are different from those cited previously. The chromosome numbers most frequently found are 2n=16 and 2n=32, only Crotalaria incana L. has 2n=14 and C. tweediana Benth. has 2n=54. The counts 2n=32 and 54 were found in species of section Calycinae and 2n=16 and 14 in species of section Chrysocalycinae. 4. Analysis of chemotaxonomic value of pyrrolizidine alkaloids (PAs) in brazilian Crotalaria species. The alkaloid composition was studied in seeds of 28 Crotalaria species, belonging to four taxonomic sections of the genus. At least 47 alkaloids were detected by gas chromatography. The sections Calycinae and Crotalaria has monocrotaline group as characteristic Pas, while senecionine group was the more prevalent alkaloid among Hedriocarpae species and part of Chrysocalycinae. The senecionine, otonecine, methylene and monoesters groups were found in some sets of species of Chrysocalycinae. 5. Comparative analysis of the morphological, citological and chemistry aspects, of sections of Brazilian Crotalaria, with emphasis on native species. The native species were inserted in the sections Calycinae and Chrysocalycinae. With reference to Chrysocalycinae, the species related to C. micans were inc1uded in Stipulosae subsection, while that species allied to C. vitelina were inserted in Glaucae section

ASSUNTO(S)

taxonomia vegetal leguminosas crotalaria alcaloides

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