Hormonal control of the outgrowth of axillary buds in Alstroemeria cultured in vitro

Abstract

We study apical dominance in Alstroemeria, a plant with an architecture very different from the model species used in research on apical dominance. The standard explant was a rhizome with a tip and two vertically growing shoots from which the larger part had been excised leaving ca. 1 cm stem. The axillary buds that resumed growth were located at this 1-cm stem just above the rhizome. They were released by removal of the rhizome tip and the shoot tips. Replacement of excised tips by lanolin with indole-3-butyric acid (IBA) restored apical dominance. The auxin transport inhibitors 2,3,5-triiodobenzoic acid (TIBA) and N-1-napthylphthalamic acid (NPA) reduced apical dominance. 6-Benzylaminopurine (BAP) enhanced axillary bud outgrowth but the highest concentrations (> 9 µM) caused fasciation. Thidiazuron (TDZ) did not show improvement relative to BAP. Even though the architecture of Alstroemeria and the model species are very different, their hormonal mechanisms in apical dominance are for the greater part very similar.

Moderate abiotic stresses increase rhizome growth and outgrowth of axillary buds in Alstroemeria cultured in vitro

“…In a previous paper, we examined apical dominance in Alstroemeria cultured in vitro (Pumisutapon et al 2011). In the present article, we show the positive effects of moderate stresses (heat, cold, drought, anaerobiosis and salt) on rhizome growth and multiplication of Alstroemeria cultured in vitro.…”

“…Rhizome growth (fresh weight increase) and multiplication (the number of new lateral rhizomes; see Pumisutapon et al 2011) were determined after 4 weeks. After severe stress treatments some explants died.…”

“…The cultures were grown at 19°C and 16 h light per day (30 lmol m -2 s -1 , Phillips TL 33). In all experiments, standard explants consisting of an intact rhizome with two decapitated shoots were used (Pumisutapon et al 2011).…”

“…Propagation in vitro is achieved by stimulating the outgrowth of axillary buds to lateral rhizomes. Even though propagation in vitro is much faster than in the greenhouse, the propagation factor in vitro is still very low and on average each rhizome produces per cycle of 4 weeks less than one lateral rhizome that is sufficiently large to separate from the main rhizome (Pumisutapon et al 2011). This is caused by strong apical dominance and poor rhizome growth.…”

In vitro Tuberization and Colchicine Content Analysis of Gloriosa superba L.

“…The strong apical dominance nature in G. superba was also recorded during its in vitro culture when only the apical buds were able to produce shoots; the nodal meristems were remained dormant even when the apical shoot tip was absent and exogenous cytokinin was present in the medium. While, the in vitro release of apical dominance and axillary buds growth using cytokinin in the culture medium, was reported in another monocot species Alstroemeria (Pumisutapon et al, 2011).…”