New chromosome numbers, meiotic behaviour and pollen fertility in American taxa of Lupinus (Leguminosae): contributions to taxonomic and evolutionary studies

Abstract

Original chromosome determinations are presented for 20 American Lupinus taxa, including, for the first time, unifoliolate species, together with first data on meiotic behaviour and pollen fertility for some South American species. Most of the Brazilian multifoliolate L. lanatus, L. rubriflorus, L. multiflorus, L. paranensis, L. bracteolaris and L. reitzii and unifoliolate L. crotalarioides, L. guaraniticus and L. velutinus accessions analysed presented regular chromosome pairing. Meiotic indexes and estimations of pollen viability were higher than 90% for all species and accessions analysed, reflecting the generally regular meiotic behaviour of these plants. Chromosome numbers were determined for the first time for the eastern South-American species L. guaraniticus, L. crotalarioides, L. paranensis, L. paraguariensis and L. velutinus (n = 18 or 2n = 36) and for the Andean L. ballianus, L. eanophyllus, L. huaronensis, L. semperflorens, plus another eight taxa (2n = 48) from Peru and Bolivia, and L. bandelierae (2n = 36) from Bolivia. Chromosome numbers were confirmed for L. lanatus, L. rubriflorus (2n = 36), L. bracteolaris (2n = 34) and L. microphyllus (2n = 48). In the three accessions of the North American unifoliolate species, L. cumulicola and L. villosus, a chromosome number (2n = 52) previously unknown among American taxa was found. The results of the study, plus published data, support the suggestions that south-eastern South American species are a group cytologically differentiated from the Andean as well as from most other American ones, and that the Brazilian and the North American unifoliolate Lupinus had independent origins.