A NEW SPECIES OF AVENA FROM SICILY, POSSIBLY THE TETRAPLOID PROGENITOR OF HEXAPLOID OATS

A new species of oat, Avena insularis, is described. It was collected in southern Sicily where four populations were found on uncultivated c lay soil. Morphologically, it is similar to the hexaploid wild oat A. sterilis, but can be distinguished by its smaller and more condensed p anicle, less V-shaped dispersal unit and oblong disarticulation scar. Hybrids between A. insularis and the hexaploid cultivated oat A. sativ a were obtained only when the latter was the seed parent in crosses. C hromosome pairing of the hybrids at meiosis was irregular with univale nts and multivalents, but the mean number of chiasmata per cell was cl ose to that of A. insularis. Furthermore, the hybrids were partially s elf-fertile. Thus, the newly discovered species seems closer to the he xaploid oats than any other tetraploid species, and is probably the te traploid progenitor of hexaploid oats. Hybrids between A. insularis an d A. magna were sterile because of irregular chromosome pairing at mei osis.