Cytogenetics and Morphology of Elymus panormitanus var. Heterophyllus and Its Relationship to Elymus panormitanus var. Panormitanus (Poaceae: Triticeae)

Abstract

Elymus panormitanus var. heterophyllus, PI-235086, was collected in Israel and became part of the National Plant Germplasm System as Elymus caninus L. in 1956. Bivalent pairing at metaphase I (MI) in E. panormitanus var. heterophyllus (2n = 42) was typical of other allohexaploids within the Triticeae. However, chromosome pairing analysis at MI of the tetraploid hybrids with Pseudoroegneria spicata (2n = 14, SS) and the pentaploid hybrids with Pseudoroegneria stipifolia (2n = 28, SSSS), Elymus lanceolatus (2n = 28, SSHH), E. panormitanus (2n = 28, SSYY), and Elymus nevski (2n = 28, SSYY) indicated that two of the three genomes of E. panormitanus var. heterophyllus were at least partially homologous to the S genome and confirmed the presence of a Y genome. Cluster analysis of 18 key characters separated E. panormitanus var. heterophyllus from E. panormitanus However, the continuous variation between the two taxa made taxonomic separation difficult unless the samples represented the two extremes. In this unique case, two taxa-E. panormitanus var. heterophyllus and E. panormitanus-were very close morphologically but different genomically. Elymus panormitanus var. heterophyllus is a hexaploid (SSSSYY; 2n = 42) and E. panormitanus is an allotetraploid (SSYY; 2n = 28).