Genome size variation among natural populations of Brachypodium distachyon and B. hybridum collected from different regions of Turkey

Abstract

Brachypodium distachyon (L) P.Beauv. is a model grass species that is useful for studying temperate cereal, forage, and energy crops. In this study we aimed to determine the genome size and species identity in the collections of the B. distachyon complex that included samples from 56 different locations in Turkey, applying chromosome counting and nuclear genome size evaluation by flow cytometry method (FCM). Moreover, the study examined whether diverse geographical conditions at the collecting sites influence the genome size. Chromosomal analysis revealed that the number of B. distachyon (x = 5, 2n = 10) genotypes was 48 and the number of B. hybridum (x = 5 + 10, 2n = 30) ones was 11. No genotypes of B. stacei were found. FCM analyses revealed that the minimum and maximum genome size of B. distachyon was 0.732 and 0.752 pg2C(-1), respectively. The mean genome size of B. distachyon was 0.743 pg2C(-1). The mean genome size of B. hybridum was 1.431 pg2C(-1) with the minimum 1.417 pg2C(-1) and maximum 1.451 pg2C(-1). Intraspecific variation in the genome size was identified for both species. It was determined that geographical origin (localization, altitude) had a statistically significant effect on genome size in B. distachyon. In addition, a negative correlation was found between altitude and genome size in this species. On the other hand, localization and altitude did not have any statistically significant effect on genome size in B. hybridum.