The Effect of Endogenous Hormones, Total Antioxidant and Total Phenol Changes on Regeneration of Barley Cultivars

Barley (Hordeum vulgar L.) is a valuable platform for producing recombinant proteins. Before using different barley cultivars as an efficient platform for molecular farming, optimization of cultural conditions and studying the effective factors on the tissue culture are critical. In this study, we evaluated callus induction, plant regeneration and changes in the levels of total antioxidant, total phenol and endogenous hormones of three Iranian barley cultivars (Reyhan, Yousef and Bahman) and Golden Promise cultivar. We used immature embryos as explants on MS-based medium containing 3 mg.L-1 2,4-D for callus induction. Calluses were transferred to regeneration media with 2 mg.L-1 BAP. The levels of endogenous hormones were measured using High-Performance Liquid Chromatography system and total antioxidant and total phenols were determined using a spectrophotometer. We demonstrated that callus formation was very high in all cultivars (about 91%) and all immature embryo explants had the potential to produce embryogenic calluses. The present study also showed that the regeneration rates among the studied cultivars were very different and the Iranian cultivars showed lower regeneration percentages (about 1.4%) compared to Golden Promise cultivar (about 72.5%). The levels of endogenous hormones in Iranian cultivars and Golden Promise varied distinctly and significant differences in terms of total antioxidants and total phenols were found in the two groups. Accumulated evidence suggests that for successful regeneration of recalcitrant cultivars, external treatments should be done in a way to reduce the inhibitory effects of internal factors.