In Vitro Multiple Bud Formation by 20-year-old Western Larch Buds and Stems

Abstract

Vegetative long-shoot buds, greenwood stems, and immature needles of 20year-old western larch (Larix occidentalis Nutt.) were cultured to induce multiple bud formation. Explants were collected year-round and cultured on a modified Schenk and Hildebrandt (SH) medium containing 6-benzyladenine (BA) at 0, 1, 5, 10, 50, or 100 µM. Multiple buds were produced on buds and stems with terminal meristems, but not on needles or stem sections. The induction of de novo buds and development of axillary buds required BA at 1 to 10 µM; higher concentrations of BA were less effective. More explants formed multiple buds on SH than on modified Murashige and Skoog (MS) media. Multiple buds formed on more buds and stems excised during the growing season than from dormant buds. Buds cultured on media containing gibberellin died within 6 weeks; auxin caused bud elongation but no multiple buds formed. Chemical names used: N-[(trichloromethyl)thio]-4-cyclohexene-1,2-dicarboximide (captan); 6-benzyladenine (BA); 1H-indole-3-butyric acid (IBA); 1H-indole-3-acetic acid (IAA); gibberellin (GA 4+7 ).

Axillary shoot proliferation in cultures of explants from mature Juniperus oxycedrus trees

“…Bud cultures in conifers have also been successfully established on media without growth regulators (Boulay 1979, Walker et al 1985, Monteuuis 1991. Because time of explant collection can influence in vitro propagation of some conifers (von Arnold 1981, Bonga 1987, Laliberté and Lalonde 1988, Chesick et al 1990, Lin et al 1991, we examined the proliferative capacity of shoot apices collected in spring, summer, autumn and winter, and cultured on agar-solidified Medium B with or without BA (0.05 and 0.5 µM). Sprouting percentages (100%) and the mean number of shoots per explant (1.6 to 2) were not significantly influenced by time of collection, but shoot length was greater (1.9 cm) on media without BA than on media containing BA (data not shown).…”

Adventitious shoot formation in cultures of 30-year-old Larix decidua, L. leptolepis, L. eurolepis, and L. laricina trees

“…The good response in late winter could be associated with a release from dormancy or, as has been speculated elsewhere (Bonga & v o n Aderkas 1991), with a specific morphogenetic event, i.e., the initiation of lateral buds. In a study with L. occidentalis, multiple bud formation was more abundant in material collected in June than at other times of the year (Chesick et al 1990). Our study did not extend into the summer season, and, therefore, we do not know if the species in our investigation would similarly be more responsive in the early summer.…”

“…Chesick et al (1990) observed formation of multiple buds in explants from 20-year-old L. occidentalis. Earlier (Bonga &von Aderkas 1988), we reported the formation of adventitious shoots in cultures of immature female cones, and of shoots excised from vegetative buds, obtained from 30-year-old L. decidua trees.…”

Gymnosperm Resprouting—A Review

“…As axillary shoot multiplication uses small shoots with nodes and internodes as explants, it is another avenue for investigating axillary meristems/buds in conifer leaf axils. Some conifer species where in vitro axillary bud development has been achieved are as follows: Araucaria and Agathis [94], Larix occidentalis [95], Podocarpus macrophyllus [96], Thuja occidentalis [88], Cephalotaxus harringtonia [97], Juniperus oxycedrus [90], Cupressus sempervirens and Chamaecyparis lawsoniana [98], Podocarpus henkelii and Podocarpus elongatus [99], Cedrus atlantica and Cedrus libani [100] and Metasequoia glyptostroboides [101]. This is a far from exhaustive listing but focusses on studies where axillary bud development was clearly demonstrated.…”