Meta-Topolin mediated in vitro propagation in an ornamentally important crop Iris × hollandica Tub. cv. professor Blaauw and genetic fidelity studies using SCoT markers

Abstract

Dutch iris is a commercially important bulbous ornamental crop. Its high demand in global floriculture market necessitates the production of its high-quality planting material. In the present investigation, an efficient in vitro propagation system has been developed for Iris × hollandica Tub. cv. Professor Blaauw (Dutch iris) using meta-Topolin (mT) for the first time. Effect of various concentrations of BAP, Kn, and mT (0, 0.5, 1.0, 1.5 and 2 mg L−1) along with varying photoperiods (16 h light and dark incubation for 1, 2, 3 and 4 weeks) on in vitro shoot induction from the twin scale explants was studied. Of the cytokinins tested, different doses of mT has resulted in better shoot induction response from twin scale explants than BAP and Kn. Photoperiod duration has also affected shoot induction response significantly. Along with dark incubation for 1 week, cytokinin mT at 1.0 mg L−1 in MS medium has resulted in maximum shoot induction response (91.63%) with increased emergence of micro shoots (4.83 shoots/explant with average shoot length of 5.02 cm). Efficacy of BAP and mT alone or in combination with auxins for in vitro shoot multiplication was also compared. The synergistic effect of cytokinin-auxin in multiplication medium comprising MS + 1.0 mg L−1 mT + 0.25 mg L−1 NAA resulted in considerably higher number of shoots (17.53) with mean shoot length (7.06 cm) and maximum number of bulblets (2.74). Positive effect of increased sucrose concentration (90 g L−1) alone or with paclobutrazol (5 mg L−1) on in vitro bulblet formation and bulblet size was observed respectively. The superiority of mT over BAP was also found during in vitro rhizogenesis. Shoots raised on the mT medium were healthy and long enough, thus showed better rooting response (63.83%) on ½ MS medium + 0.5 mg L−1 IAA after 4 weeks of incubation. About 89.16% survival rate was recorded for in vitro raised plantlets under ex vitro conditions. Analysis of clonal fidelity of thirteen in vitro regenerated plants was done using SCoT markers. Out of 36 primers, 13 primers showed clearly scorable monomorphic bands, thus displaying genetic uniformity among in vitro regenerated plantlets. This mT mediated protocol can be routinely used for the rapid large scale production of this valuable floriculture crop.