Phase change in lily bulblets regenerated in vitro

Abstract

During the development of the lily (Lilium), three phases can be distinguished: the juvenile, the vegetative adult and the flowering phase. Juvenile bulblets sprout with one or a few leaves whereas vegetative adult bulblets sprout with a stem with elongated internodes. The transition to the vegetative adult phase was studied in lily (Lilium × cv. Star Gazer) bulblets regenerating on bulb scale segments in vitro. The phase change was marked by the development of a tunica‐corpus structure in the apical meristem which leads to the formation of an actively growing stem primordium. This structure is absent in juvenile bulblets. Juvenile bulblets first developed competence for phase change during a culture period of at least 6 weeks at 25°C. Subsequent induction of the phase change occurred during a period of 2 weeks at lower temperature (15°C). A major factor influencing phase transition was bulblet weight. Small bulblets never formed a stem whereas large bulblets always formed a stem under inducing conditions. Large bulblets more often formed a stem than small ones but the relation between bulb growth and phase transition was not absolute. A high sucrose concentration, a large explant and a prolonged period for competence development stimulated bulb growth but also phase transition independently of growth. Lowering the concentration of MS‐minerals reduced bulb growth but did not affect phase transition. Under these conditions, phase change was correlated with a low phosphorus content.

Etiolation and flooding of donor plants enhance the capability of Arabidopsis explants to root

“…Wu and Poethig (2006) showed that phase transition from juvenile to mature is stimulated by a high endogenous sucrose level. This seems to be a general mechanism as the same was found in lily (Langens-Gerrits et al 2003). In the juvenile phase, miR156 is highly expressed and its expression decreases dramatically during vegetative phase change (Wu and Poethig 2006).…”

Factors affecting bulblet growth of Lilium sp. in vitro and in vivo

“…In addition, sprouting type is directly related to a switch in ontogenetic development from juvenile to adult vegetative ( Figure 6). When bulblets are small (<300 mg), they sprout rosette-type of leaves instead of leaves with a stem (Langens-Gerrits et al, 2003a), so there was no adult vegetative bulb in this study. Therefore, the results from this in vivo study indicate that increasing bulblet size during in vitro culture is the main point of interest for future production.…”

Bulb and vegetative characteristics of garlic (Allium sativum L.) from in vitro culture through acclimatization and field production

“…However, the development rate was the closest between the third and fourth generation in which garlic plants reached the commercial size. Previous studies on in vitro cultured lily bulblets revealed that the transition from juvenile to vegetative adult is characteriz-ed by increased mitotic activity in the apical meristem, followed by stem elongation (Langens-Gerrits et al, 2003). This step was related to weight of the bulblets (Niimi, 1995;Langens-Gerrits et al, 2003) and their size (Matsuo and Arisumi, 1978).…”

“…Previous studies on in vitro cultured lily bulblets revealed that the transition from juvenile to vegetative adult is characteriz-ed by increased mitotic activity in the apical meristem, followed by stem elongation (Langens-Gerrits et al, 2003). This step was related to weight of the bulblets (Niimi, 1995;Langens-Gerrits et al, 2003) and their size (Matsuo and Arisumi, 1978). It seems that a number of growing seasons are necessary for tissue cultured bulblets to reach the adult and commercial size.…”