Micropropagation ofPenstemon serrulatus and iridoid formation in regenerated plants

Abstract

A method for the micropropagation of Penstemon serrulatus Menz. from shoot tips or nodal segments was developed. Multiple microshoot cultures (up to 20 shoots from a single explant) were obtained by maintenance of shoot tip explants on Schenk & Hildebrandt medium (SH) supplemented with 4.4 I~M benzyladenine (BA) or 8.9 IxM BA and 0.57 IxM indole-3-acetic acid (IAA). Microshoots developed into numerous, normal shoots when explants were transferred to SH medium containing 2.9 IxM IAA or 2.5 I~M indole-3-butyric acid (IBA). Shoot cultures were also established from nodal segments (max. 6.8 shoots per segment) when they were placed on SH medium with 0.49 ixM IBA and 2.2 IxM BA. Rooting of shoots was better on SH medium containing auxin (IBA, NAA or IAA) than on SH medium without growth regulators. The plantlets were then transferred to pots and grown in the greenhouse. Four-month-old regenerated plants demonstrated similar iridoid content (leaves contained 3.83% dry wt. penstemide and 1.8% dry wt. serrulatoloside) as the original plants.

Micropropagation of Baptisia `Purple Smoke'

“…Roots formed above the medium produced many root hairs. Variation in root morphology in response to different PGR treatments has been reported for other taxa, such as Penstemon serrulatus Menzies ex Smith (Wysokinska, 1993). All four K-NAA treatments significantly stimulated callus production on rooted shoots (Table 2); the quantity of callus formed appeared to be greatest for the two highest K-NAA treatments (data not shown).…”