Micropropagation of Spigelia marilandica L.

Abstract

Commercial micropropagation of Spigelia marilandica (Loganiaceae) requires the development of proliferation and rooting protocols for in vitro-generated microcuttings. Seedling microshoot explants formed the most axillary shoots when cultured on half-strength Murashige and Skoog basal medium supplemented with 11 or 22 μM benzyladenine. Monthly serial subculture of shoot cultures for 6 mo had no impact on the mean total number of axillary shoots formed. Microshoot explants with shoot tips formed more axillary shoots compared to single nodes, and microshoot explants with basal nodes formed more axillary shoots compared to microshoot explants without basal nodes. Microcuttings were rooted ex vitro. Microcuttings, 1-2 versus 2-5 cm in length, rooted equally well whether placed in RediEarth, sand, or vermiculite. After potting, plants from short and long microcuttings grew equally well based on leaf number and stem height; however, plants grown in the sun had more leaves and were taller than plants under 50% shade (6 versus 3.1 cm in height, respectively). Microcuttings dipped in indolebutyric acid, 500 or 1000 ppm, had more roots with longer mean total root lengths compared to control microcuttings. Microcuttings grown under mist for 4 wk survived better than those under mist for 6 wk. Neither microcutting age (6, 8, 12, 16, or >20 wk post-subculture) nor cold storage (8, 12, or 16 wk post-subculture; 6°C for 7 wk) affected the percent of shoots with roots (100%), mean root number, or mean total root length. Field-grown in vitroderived plants (60% survival) had more stems and more leaves compared to field-grown seedlings of comparable age (90% survival). Micropropagation of S. marilandica on a commercial scale has practicality based on the ease with which microshoot explants formed axillary shoots in vitro and microcuttings rooted ex vitro.

An improved micropropagation system, ex vitro rooting and validation of genetic homogeneity in wild female Momordica dioica: an underutilized nutraceutical vegetable crop

“…Use of quarter strength of aqueous MS salts (instead of full strength MS) provided starvation to develop roots, as updates are available on molecular determinants of low nitrogen availability-specific regulators that favor primary and lateral root growth/development (Kiba and Krapp 2016). Ex vitro rooting is more beneficial than in vitro rooting in terms of cost, time, labor and chemical consumption; and the resultant plants get concurrently acclimatized (Hatzilazarou et al 2006;Agarwal et al 2015;Kitto 2015;Bohra et al 2016).…”