Cytology of the Elymus (Agropyron) elongatus complex

Abstract

The taxa cytologically studied in the Elymus (Agropyron) elongatus complex included three subspecies of E. elongatus, i.e., ssp. elongatus and ssp. haifensis (2n= 14) and ssp. flaccidi‐folius (2n = 28), as well as E. varnensis (2n = 70). A brief taxonomic treatment of these different types is presented. Differences in karyotype were observed between materials of ssp. elongatus that have different origin as well as between ssp. elongatus and ssp. haifensis. Both subspecies have heteromorphic chromosome pairs. In the case of ssp. flaccidifolius, it was possible to arrange the chromosomes in seven groups of four. These groups correspond to the seven pairs of the diploid subspecies which indicates the likelihood of an autopolyploid origin of the tetraploid subspecies. That the chromosomes in most of these groups could be further differentiated into pairs suggests that “intervarietal” crossings have also been involved. Meiosis was studied in ssp. elongatus and flaccidifolius. The satellited chromosomes detectable in E. varnensis were few; they represent, however, types that are found in the three subspecies of E. elongatus. This indicates that the two species are interrelated.

Genome Size in Diploids, Allopolyploids, and Autopolyploids of Mediterranean Triticeae

“…Beauv. ], exhibit exclusive or almost exclusive bivalent pairing at meiosis in spite of the fact that originally they contained two or more homologous genomes [96][97][98]. The cytologically diploidized autopolyploids, being more fertile than the typical ones, are prevalent among annual species.…”

Autoploid origin and rapid diploidization of the tetraploid Thinopyrum elongatum revealed by genome differentiation and chromosome pairing in meiosis

“…This autopolyploid origin of the tetraploid Th. elongatum was also characterized by the occasional formation of quadrivalents at meiosis (Heneen & Runemark, 1972). A high level of pairing was exhibited by the triploid hybrids between the natural tetraploid and diploid cytotypes, 4.15 bivalents and 2.82 trivalents per cell, also supporting the assumption that the natural tetraploid is of an autoploid origin (Charpentier et al., 1986).…”

“…The species Thinopyrum elongatum is composed of diploid (2 n = 2 x = 14), tetraploid (2 n = 4 x = 28) and decaploid (2 n = 10 x = 70) cytotypes. From its karyotype and gross morphology, it was concluded that the tetraploid was an autotetraploid, with two genomes undergoing some differentiation (Breton‐Sintes & Cauderon, 1978; Heneen & Runemark, 1972). This finding was further supported by the degree and pattern of chromosome pairing in F 1 triploid hybrids between the two cytotypes (Dvořák, 1981).…”

Karyotype Analysis and Giema C-Banding Patterns in <i>Thinopyron elongatum</i>

“…As a perennial plant, Thinopyron elongate presents significant features of resistance to drought and diseases. The chromosome complement of it was named as EE, there are diploid (EE), tetraploid (E1E1E2E2), and decaploid (EE1E2E4E5) according to cytological classification [6,7] . In Thinopyron elongate, the study on karyotype and banding was started later because of the technical limitation in Thinopyron, in which chromosomes showed less bands by conventional staining method used for wheat.…”