Number, morphology and C banding variability of B chromosomes in Aegilops speltoides Tausch

Abstract

Plants of the species Aegilops speltoides were collected in six localities of Israel: Haifa 1, Haifa 2, Ramat. Ara, Benaya and Ashkelon. They were studied for B chromosome polymorphism. Benaya and Ashkelon, located to the South of the Mediterranean coast, lack B chromosomes (Bs), while Haifa 1, Haifa 2, Ramat and Ara, located to the North, have Bs. It seems that Bs are present only in populations living in localities favourable for the species. We found variability for C heterochromatin in the Bs. The standard type ís submetacentric, with a large pericentromeric C-band, and two small C-bands, one on each arm. The pericentromeric C-band is constató while the other C-bands are highly variable. The most frequent B types found in these populations can be explained by recombination between Bs with and without C-bands. We have also found Bs with structural mutations. This highly polymorphic structure of the Bs can be explained by their lack of specific genetic function.