4.1. Plant Material

Two barley genotypes were used in the experiment. Wild type (WT) of Hordeum vulgare L. cv. Golden Promise was used as a control and transgenic barley lines of the same cultivar overexpressing cDNA of the barley phytoglobin (formerly hemoglobin) gene HvPGB1-1 (accession number: {"type":"entrez-nucleotide","attrs":{"text":"U94968","term_id":"2071975","term_text":"U94968"}}U94968) controlled by the maize ubiquitin2 promoter. The transgenic line was described in [28] and is designated as HO (for hemoglobin overexpressor).

Barley plants were grown from seeds on moistened filter paper for 8 days in a growth chamber (19 ± 1 °C) with photoperiod of 16 h light/8 h darkness with ~120 μmol·m⁻²·s⁻¹ (6480 lux) of light intensity and relative humidity of 70%.