Vigna luteola (Jacq.) Benth. and V. marina (Burm.) Merrill are two closely related species belonging to the section Vigna of the subgenus Vigna. Both taxa are distributed throughout the tropics and show great similarities in their morphological traits (e.g. floral structure), being distinguishable on the basis of some vegetative characters and on their different ecological requirements. To better understand the genetic relationships between the two species at the intra and interspecific level, a total of 26 accessions were used to perform isozyme and RAPD analyses (19 belonging to V. luteola. 5 to V. marina ssp. oblonga and 2 to V. marina ssp. marina). Over a total of 13 loci scored, 7 were polymorphic. Very low values of genetic diversity indices were found for each species and Nei's genetic distances among accessions were also very low. Genomic DMA amplification using 14 selected decamer oligonucleotides allowed us to score 85 bands, 66 of which were polymorphic. Based on the presence or absence of bands, Jaccard's similarity index was calculated. Matrices derived from isozyme or RAPD data were used to construct UPGMA dendrograms. In the dendrogram derived from allozyme frequencies, the accessions belonging to V. marina ssp. oblonga were mixed with V. luteola ones, whereas the two accessions of \L marina ssp. marina clustered separately with one V. luteola. The dendrogram obtained from RAPD bands showed three main clusters corresponding to the three taxa analysed; also in this case, V. marina ssp. oblonga was more closely related to the V.. luteola accessions than to the other V. marina samples. In the light of the present analyses, it appears that the botanical classification seems to be strongly biased towards ecogeographical considerations not adequately supported by genetic and morphological data. Although further gene flow studies might certainly provide useful information on the existing relationship between the two taxa, the study herein reported might contribute for a more realistic interpretation of evolutionary trends involved.
Genetic relationships within and between Vigna luteola and V. marina (Leguminosae)
Sonnante G;Pignone D
1997
Abstract
Vigna luteola (Jacq.) Benth. and V. marina (Burm.) Merrill are two closely related species belonging to the section Vigna of the subgenus Vigna. Both taxa are distributed throughout the tropics and show great similarities in their morphological traits (e.g. floral structure), being distinguishable on the basis of some vegetative characters and on their different ecological requirements. To better understand the genetic relationships between the two species at the intra and interspecific level, a total of 26 accessions were used to perform isozyme and RAPD analyses (19 belonging to V. luteola. 5 to V. marina ssp. oblonga and 2 to V. marina ssp. marina). Over a total of 13 loci scored, 7 were polymorphic. Very low values of genetic diversity indices were found for each species and Nei's genetic distances among accessions were also very low. Genomic DMA amplification using 14 selected decamer oligonucleotides allowed us to score 85 bands, 66 of which were polymorphic. Based on the presence or absence of bands, Jaccard's similarity index was calculated. Matrices derived from isozyme or RAPD data were used to construct UPGMA dendrograms. In the dendrogram derived from allozyme frequencies, the accessions belonging to V. marina ssp. oblonga were mixed with V. luteola ones, whereas the two accessions of \L marina ssp. marina clustered separately with one V. luteola. The dendrogram obtained from RAPD bands showed three main clusters corresponding to the three taxa analysed; also in this case, V. marina ssp. oblonga was more closely related to the V.. luteola accessions than to the other V. marina samples. In the light of the present analyses, it appears that the botanical classification seems to be strongly biased towards ecogeographical considerations not adequately supported by genetic and morphological data. Although further gene flow studies might certainly provide useful information on the existing relationship between the two taxa, the study herein reported might contribute for a more realistic interpretation of evolutionary trends involved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
