Inflorescence Development in Allium ampeloprasum var. babingtonii (Babington’s Leek).

Harding, Samantha (2004) Inflorescence Development in Allium ampeloprasum var. babingtonii (Babington’s Leek). PhD thesis, University of Worcester/Cardiff University.

Abstract

Within the horticultural industry, clonal propagation is desirable allowing for the maintenance of true lines, with more uniform cropping and flowering characteristics. Clonal propagation through tissue culture can be expensive, requiring equipment and facilities not always available to the breeder, whilst more traditional methods of clonal propagation may be slow, producing limited numbers.

Many Alliums produce bulbils or have the ability to produce bulbils if appropriate conditions prevail. Allium ampeloprasum var. babingtonii always produces both sterile florets and bulbils in the inflorescence as well as daughter bulbs and bulblets. The ability to manipulate the inflorescence towards the production of bulbils may lead to improved methods of clonal propagation. Literature suggests that bulbil production may involve reversion or partial reversion of floral primordia at critical stages in inflorescence development.

Wax embedding, sectioning and staining techniques have been used to examine bulb physiology, and allowed the construction of a developmental timetable. A protocol was developed for the maintenance of apices in tissue culture to monitor floral determination of the apex. The sampled population of Allium ampeloprasum L. var. babingtonii (Borrer) Syme was found to have both a vernalization requirement and a maturity requirement for floral competence. Vernalization for six weeks at 7° C produced 100 % flowering in plants with a minimum size of 3 cm diameter or approximately 13 g mass at the beginning of the growth season, producing ten or eleven leaves prior to expression of the floral state. Determination occurred during February; the meristem widened followed by elongation of the scape and development of the spathe. Cymes develop in a regular pattern over the inflorescence, florets forming initially with bulbils developing at the base of the pedicels.

Gene expression in Allium species has been not recorded in detail, but comparisons with Arabidopsis and other monocotyledons such as rice (Oryza sativa) have provided a working model. Degenerate primers were constructed based on the rice RLF (Rice LEAFY homologue) gene. This was used to establish the presence of a putative homologue in Allium ampeloprasum var. babingtonii (ABLFY), this being expressed in floral meristems but not vegetative meristems.

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