Abstract
In this study, the hypocotyls of quinoa (cultivar 'Qingqua I') were used as the initial explants. The effects of plant growth regulators (PGRs) on induction of quinoa hypocotyl callus, adventitious shoots, and their elongation were investigated. The surface sterilization of seeds was conducted through sequential immersion in 75% (v/v) ethanol and 10% (v/v) sodium hypochlorite solution. The influence of proline concentrations for texture of callus, and macroelement levels of Murashige and Skoog (MS) medium for overcoming premature senescence of shoots were explored. The highest induction of callus (97.78 ± 1.92%) was observed in presence of 0.2 mg/L 6-benzyl adenine (BA) and 2 mg/L 1-naphthaleneacetic acid (NAA) in MS medium. The highest densities of callus (0.42 ± 0.006 g/cm(3)) were achieved on MS medium containing from 1 mg/L BA, 0.1 mg/L NAA, and 0.2 g/L proline, which was optimum for induction of adventitious shoots, exhibiting the highest rate of adventitious shoot regeneration of 89.63 ± 2.67% and the highest adventitious shoot number of 40.50 ± 0.74. The best medium for overcoming the premature senescence of shoots was the medium with triple macronutrients (3MS) of 0.1 mg/L BA and 0.01 mg/L NAA. The exhibited a premature senescence rate of only 8.15 ± 1.09%, an elongation rate of 88.76 ± 1.14% of adventitious shoots, mean height of shoot per explant was 6.85 ± 0.02 cm, robust shoots and tender green leaves. For rooting, the best medium was the one which contained 0.6 mg/L indole-3-butyric acid (IBA), in which rooting was observed after 9.0 ± 0.3 d of rooting d, 98.52 ± 0.75% of rooting rate, and 16.90 ± 0.38 mean number of roots per explant were achieved. For the first time, we have overcome the challenge of premature senescence in quinoa, and this can be useful for other species.