**5. Sizing the Large Triticeae Genomes**

Three species belonging to the tribe Triticeae—namely, bread wheat (*Triticum aestivum*), barley (*Hordeum vulgare*) and to a lesser extent, cereal rye (*Secale cereale*)—provide a major proportion of the calories used by humans and their livestock across the temperate world. The acquisition of their genome sequences will facilitate marker- and genomics-assisted breeding, gene editing and other novel breeding technologies currently under development. Reference genome sequences have been published for barley [21], wild emmer wheat (*T. dicoccoides*) [22] and hexaploid bread wheat (*T. aestivum*) [3], and one for cereal rye is currently being finalized (Nils Stein, pers. comm.). Here, flow cytometry was utilized to assess the nuclear DNA content of wild emmer, bread wheat, barley and cereal rye. To minimize errors due to copy number variants and intraspecific differences in genome size, the accessions of each species were those used for the acquisition of their genome sequences. The cereal rye cultivar Daˇnkovské (16.19 pg/2C) and garden pea (*Pisum sativum*) cultivar Ctirad (9.09 pg/2C) were used as reference standards (Table 1). Rye was selected out of the calibrated reference standards (Table 1) as its 2C value was close to 2 C DNA amounts of tetraploid and hexaploid wheat and barley. However, this standard could not be used for another accession of rye and thus pea was employed as the second standard. The outcomes are summarized in Table 2.


**Table 2.** Estimation of nuclear DNA amounts in the four Triticeae species.

\* Considering 7 pg DNA/2C for human [9].
