Direct Shoot From Root and True-to-Type Micropropagation of Limonium "Misty Blue" in Partially Immersed Culture on an Aluminum Mesh Raft

Abstract

Commercial plant tissue culture now primarily serves the ornamental horticulture industry. The main pillars of the commercial tissue culture business are scalability of production, cost reduction, limited labor involvement, high quality, and genetic homogeneity of propagated plants. Based on these requirements, the current protocol employs a partially immersed liquid culture medium supported by a flexible aluminum mesh raft with a wire stand to facilitate shoot organogenesis from the horizontally placed root explants and hold the plants upright for shoot multiplication and rooting of Limonium Misty Blue. It is a florist crop that is in high demand as both dried and fresh flower fillers in various floral decorations. The majority of cultivated Limonium or statice cultivars are heterozygous in nature and propagate commercially through in vitro propagation to cater to the huge demand for planting materials needed for flower production. This is the first protocol to describe direct shoot organogenesis from the roots in a liquid half-component of Murashige and Skoog's (1962) (MS) basal medium supplemented with 1.6 μM NAA and 1.1 μM BA. The regenerated shoots are multiplied and rooted at the same time on the raft in a MS-based liquid culture medium that included 0.44 μM BA and 1.07 μM NAA. In comparison to agar-gelled medium, plants cultured in liquid medium grow more quickly without any signs of hyperhydricity. In liquid medium, a clump of 4-5 shoots is formed from a single shoot explant within 4 weeks and are rooted simultaneously within 6 weeks. On average, seven explants may fit on each raft, so on average, 25 healthy plants are produced from a single bottle. The regenerated plants are easily hardened in the greenhouse, and using ISSR-based molecular markers, the genetic homogeneity of the randomly selected hardened plants can be determined.

Keywords: Hardening; ISSR; In vitro propagation; Liquid culture; Organogenesis; Rooting; Shoot proliferation; Statice.