In vitro propagation of the Damask rose (Rosa damascena Mill.)

Abstract

Roses are an important commercial crop available in a wide range of varieties in international markets. Due to its economic value, this study aimed to establish a new and reproducible protocol for the in vitro propagation of Rosa damascena Mill. We developed an efficient and cost-effective method for rapid and high-quality shoot multiplication and in vitro rooting of Damask rose using nodal explants. For each stage of the micropropagation procedure (i.e., explant establishment, shoot multiplication and growth, and rooting), different media and combinations of plant growth regulators were utilized. A new culture medium, termed A₁₉, resulted in significant improvements to shoot proliferation and root induction for this rose cultivar. For optimal explant establishment, shoot growth, and proliferation, a modified Murashige and Skoog medium with higher levels of nitrates, calcium, and iron plus supplementation with 4 mg/l 6-benzylaminopurine and 0.25 mg/l indole-3-acetic acid was utilized. To increase shoot length, 75 d after culture initiation (including two subcultures), shoots were transferred to the same medium additionally supplemented with 0.2 mg/l gibberellic acid. This resulted in vigorous shoot growth, with longer shoots and a greater number of shoots per explant. Shoots were then separated and transferred to various root induction medium for 30 d. The results clearly showed that a liquid ½A₁₉ medium-A (i.e., with half-strength macroelements) supplemented with 0.1 mg/l indole-3-butyric-acid was the most successful medium for in vitro rooting in this cultivar. Shoots were cultured in this medium for 7 d in the dark, before transfer to liquid ½A₁₉ medium-A without hormone supplementation under a 16-h photoperiod. This modified protocol resulted in significant improvement in shoot regeneration and proliferation and obtained stronger shoots over a period of about 20 wk.