An efficient in vitro regeneration system via callus from hypocotyl and root of Iris laevigata

Abstract

Background Iris laevigata is an ornamental plant with strong cold resistance. However, its low reproductive capacity limits its landscape applications. The I. laevigata wild genetic resources also need to be protected. In order to develop an effective regeneration system, the optimum agar concentration for the induction medium was determined. Two explants (hypocotyl and root) were then cultured on medium containing different concentrations of plant growth regulator (PGR). In addition, three antibiotics were evaluated for controlling endophyte contamination. Results The highest induction rate (75.00%) was obtained from hypocotyl explants on Murashige and Skoog salt mixture (MS) medium containing 6-benzylaminopurine (6-BA) 0.5 mg L-1 + 2,4-Dichlorophenoxyacetic acid (2,4-D) 1.0 mg L-1 + 1-naphthylacetic acid (NAA) 0.4 mg L-1. The medium containing 6-BA 0.5 mg L-1 + 2,4-D 0.5 mg L-1 + NAA 0.2 mg L-1 achieved the greatest multiplication rate (73.33%). Media containing indole-3-butyric acid (IBA) 0.5 mg L-1 + 6-BA 1.5 mg L-1 + NAA 1.0 mg L-1 achieved the highest differentiation rate (39.72%) for hypocotyl induced calli. Medium containing 6-BA 2.0 mg L-1 + NAA 0.4 mg L-1 + kinetin (KT) 1.0 mg L-1 resulted in the highest differentiation rate (49.52%) for root induced calli. One hundred mg L-1 penicillin G resulted in the optimal rate for reducing endophyte contamination. Conclusions The research determined the optimum PGR concentrations for inducting and multiplying I. laevigata calli from hypocotyl and root explants and a satisfactory means for control endophyte contamination. This research will result in the efficient and reliable reproduction of I. laevigata for landscape applications, genetic development of new Iris varieties, and preservation of the wild genetic material.