Elongation, rooting and acclimatization of micropropagated shoots from mature material of hybrid larch

Abstract

Factors were defined for elongation, rooting and acclimatization of micropropagated shoots of Larix x eurolepis Henry initiated from short shoot buds of plagiotropic stecklings serially propagated for 9 years from an 8-year-old tree. Initiation and multiplication were on Schenk and Hildebrandt (SH) medium supplemented with 5 ~M 6 -benzyladenine (BA) and 1 ~tM indole-butyric acid (IBA). Stem elongation was obtained in 36% of the shoots on SH medium containing 0.5 laM BA and 63% of the remaining non-elongated shoots initiated stem elongation after transfer on SH medium devoid of growth regulators. Rooting involved 2 steps: root induction on Campbell and Durzan mineral salts and Murashige and Skoog organic elements, both half-strength (CD-MS/2), supplemented with 1 ~tM of both naphthaleneacetic acid (NAA) and IBA, and root elongation following transfer to CD-MSI2 medium devoid of growth regulators. Repeating this 2-step sequence yielded up to 67% rooted shoots. Acclimatization of plantlets ranged from 83% to 100%. Over 300 plants were transferred to the greenhouse; some showed plagiotropic growth.

Multiple shoot induction and plant regeneration of the single-cell C4 species Bienertia sinuspersici

“…Similar reports were observed in apple micropropagation or regeneration where BA induced several side effects, such as difficulties in rooting, hyperhydricity and stunted shoots (Magyar-Tabori et al 2010) and abnormal growth in Spathiphyllum floribundum (Werbrouck et al 1995(Werbrouck et al , 1996. An inhibitory effect of BA on shoot elongation has also been observed in many micropropagation protocols (Ault 1994;Iriondo et al 1995;Brassard et al 1996;Figueiredo et al 2001). Moreover, low concentrations of BA are often recommended to replicate shoots in vitro because of interactions between residual PGRs will affect micropropagation success during elongation and rooting (Magyar-Tabori et al 2010).…”

Efficient in vitro plant regeneration from shoot apices and gene transfer by particle bombardment in Jatropha curcas

“…Reduction of the BAP concentration in subculture medium was not favourable for shoot elongation, furthermore, it lead to the loss of shoot multiplication capacity. The BAP have often been reported to stimulate shoot proliferation while inhibiting shoot elongation (Brassard et al 1996, Figueiredo et al 2001. Shoots regenerated on kinetin-supplemented medium showed comparatively better elongation than those regenerated on the medium containing other cytokinins.…”

Morphogenesis in Sitka spruce (Picea sitchensis (Bong.) Carr.) bud cultures – tree maturation and explants from epicormic shoots

“…Although only one plantlet from the latter survived transfer to the soil, it eventually showed orthotropic growth, grew to 260 cm tall in 7 years and remained in a juvenile none-flowering condition (Bonga, 1997). In vitro shoot elongation and rooting of mature tissues is also reported for Larix species following either micrografting (Ewald and Kretzschmar, 1996) or serial propagation via rooted cuttings (Brassard et al, 1996). Shoots from mature trees of Juniperus oxycedrus, grown by axillary shoot proliferation, could not be rooted (Go´mez and Segura, 1995), whilst adventitious shoots produced from leaves showed a high rooting potential (Go´mez and Segura, 1994) suggesting adventitious shoot initiation can achieve rejuvenation with this species.…”