Polyploidy and Apomixis in Apluda mutica L. var. aristata (L.) Pilger

抄録

Cytological, embryological and hereditary behaviour of twenty six collections of Apluda mutica L. var. aristata (L.) Pilger are reported. Ten accessions were diploids with n=10 chromosomes. Meiosis in these accessions was regular with the formation of 10 bivalents at diakinesis and metaphase I and with a regular distribution of 10 chromosomes to each pole at anaphase I. Embryo sacs were usually 8-nucleate, and 4-nucleate embryo sacs were rare. Out of the other 16 accessions, 10 were hexaplids with a chromosomal count of n=30 and 6 were heptaploids with n=35. Meiosis in these accessions was irregular with multivalent chromosome associations at diakinesis and metaphase I, laggards at telophase I and telophase II and pollen tetrads with micronuclei. In all the asseccions of the two polyploids races, both 4-nucleate and 8-nucleate embryo sacs were encountered. The mechanism of apomixis is pseudogamous apospory. It is concluded that Apluda mutica represents a polyploid complex with 2n chromosome numbers ranging from 20 to 70, the diploids being largely sexual and the polyploids being facultative apomicts.