INTRAVARIETAL VARIATION IN SATELLITES AND C-BANDED CHROMOSOMES OF AGROPYRON INTERMEDIUM SSP TRICHOPHORUM CV GREENLEAF

A high amount of intravarietal variation in satellites and C-banded ch romosomes was observed in the hexaploid wheatgrass synthetic cultivar 'Greenleaf' (Agropyron intermedium ssp. trichophorum (Link) A. and Gr. , 2n = 6x = 42, genome E,E,E,E,SS). The cultivar is an open-pollinated perennial that shows extensive interplant polymorphism for many biolo gical characters. Maximum number of satellites detected varied among p lants from zero to six. In 61% of the plants, we observed two large sa tellites in association with zero, one, or two small ones. Chromosome constitution differed significantly among plants as revealed by analys is of variance based on the total number of banded chromosomes and the number of banded chromosomes with telomeric bands at either one or bo th ends. Heteromorphism in C-banding patterns between homologues was f ound in most of the chromosomes and was classified into four types: (i ) difference in band size, (ii) difference in presence/absence of one or two bands, (iii) completely different banding patterns, and (iv) ba nded versus unbanded. Homologous chromosomes having types ill and iv h eteromorphism could only be matched by their relative length and arm r atio instead of C-banding patterns. Deletions were detected in two chr omosomes. Overall, C-banded chromosomes of this cultivar were characte rized by the presence of large telomeric bands and were quite differen t from the previously reported karyotypes of the supposed diploid ance stor Agropyron elongatum (Host) P. Beauv. (genome EE) and an Ag. inter medium (Host) P. Beauv. accession (E,E,E,E,SS). The results suggest th at dramatic chromosome modifications have occurred in this species dur ing the course of evolution. The study sheds light on the extent of in trapopulation polymorphism present in the karyotypes of outcrossing po lyploids and synthetic cultivars and has implications regarding strate gies for chromosomal manipulation involving open-pollinated species.