PROPAGATION AND CONSERVATION OF CASTILLEJA TENUIFLORA BENTH. (“HIERBA DEL CANCER”) THROUGH IN VITRO CULTURE

Abstract

We undertook this study to (1) evaluate an
in vitro procedure for plantlet regeneration
of Castilleja tenuiflora Benth. (Scrophulariaceae) from axillary buds and (2) induce
callugenesis and organogenesis through
the manipulation of explant type, culture
media and plant growth regulators. An
efficient propagation protocol for in vitro
multiplication and plantlet regeneration of
C. tenuiflora using axillary buds of wild
plants was developed. Shoot multiplication
was induced from axillary buds in Murashige and Skoog (MS) medium containing
0.2 mg L-1 BAP and 0.1 mg L-1 NAA with
an efficiency of 33%. Shoot multiplication
and elongation were achieved in one step
using 0.1 mg L-1 IBA and 0.25 mg L-1 BAP.
After 14 days, an average of four shoots
per explant was observed. For rooting, IBA
was increased to 1.0 mg L-1 and BAP was
excluded. Hyperhydricity was not observed
and 88% of the shoots rooted. From one
axillary bud, 250 plantlets were produced
within eight weeks. To induce callugenesis
and organogenesis, explants (leaves and
internodes) from plantlets were excised
and inoculated into MS, B5 and NN culture media in combination with NAA (0-10
μM) and kinetin (0-0.5 μM). In general,
rhizogenesis was the main in vitro response
(up to 100%) followed by shoot formation
(5-50%) and, finally, callugenesis (2-35%).
Internodes were more competent than
leaves for both callugenesis and organogenesis, along with the fact that leaf explants
oxidized easily. Rhizogenesis depended on
exogenous NAA, but auxin requirement
varied according to the culture medium
and type of explant used. On the basis of
our results, conditions for callugenesis and
organogenesis induction of C. tenuiflora
can be recommended: a) callus-internode,
0.1 μM NAA and B5 medium; b) rhizogenesis-0.1 μM NAA and NN medium; and
c) shoots-internode, 0.1 μM NAA and MS
medium. Results of the present study show
the feasibility of using in vitro culture to
propagate and conserve germplasm of the
‘cancer herb’ C. tenuiflora.