Comparative morphological and cytogenetic study of five Asparagus (Asparagaceae) species from Algeria including the endemic A. altissimus Munby

摘要

Forty wild populations belonging to five Asparagus species including the endemic A . altissimus were sampled in an east-west bioclimatic gradient of North Algeria. More than 250 individuals were taxonomically examined and karyologically investigated. Meiotic behavior was analyzed for each species. New chromosome numbers were consistent with the base number x = 10 for the genus Asparagus , and two cytotypes, diploid and hexaploid, were observed. Four species were found to have 2n = 20 chromosomes, highlighting the prominence of diploidy in North Africa. One polyploid with 2n = 60 is reported here as the first karyological information on the endemic A. altissimus . Karyotype parameters were established and compared for diploid species. New data provided for A. acutifolius and A. albus indicate differences in the number of submetacentric chromosomes and genome size estimated by total chromosome length. A. a cutifolius is distinguished by the largest genome, the smallest being that of A. horridus . The hexaploid cytotype consists of very small metacentric chromosomes. All diploid species displayed regular meiotic behavior with mostly bivalent pairing. Abnormalities, including univalents, multivalents, laggards, and bridges, were sometimes observed in A . horridus and A . officinalis . The new cytogenetic information provided in this study is discussed in the biogeographic context of the North African flora.