Flowering pathway is regulated by bulb size in Lilium longiflorum (Easter lily)

Abstract

Lilium longiflorum (Easter lily) vegetative propagation occurs through production of underground bulbs containing apical and axillary meristems. In addition, sexual reproduction is achieved by flowering of elongated shoots above the bulb. It is generally accepted that L. longiflorum has an obligatory requirement for vernalisation and that long day (LD) regime hastens flowering. However, the effect of bulb size and origin, with respect to axillary or apical meristems on flowering, as well as the interactions between these meristems are largely unknown. The aim of this study was to explore the effect of bulb size, vernalisation and photoperiod on L. longiflorum flowering. To this end, we applied vernalisation and photoperiod treatments to the different bulb sizes and used a system of constant ambient temperature of 25 °C, above vernalisation spectrum, to avoid cold-dependent floral induction during plant growth. Vernalisation and LD hasten flowering in all bulbs. Large, non-vernalised bulbs invariably remained at a vegetative stage. However, small non-vernalised bulbs flowered under LD conditions. These results demonstrate for the first time that cold exposure is not an obligatory prerequisite for L. longiflorum flowering, and that an alternative flowering pathway can bypass vernalisation in small bulbs. We suggest that apical dominance interactions determine the distinct flowering pathways of the apical and axillary meristems. Similar floral induction is achieved in propagated bulblets from scaling. These innovative findings in the field of geophyte floral induction represent valuable applicative knowledge for lily production.

The metabolic (under)groundwork of the lily bulb toward sprouting

“…Plants from non‐cooled large bulbs grown at 25°C produced many leaves but did not flower even after more than 6 months, as previously observed (Lazare and Zaccai ). Cold exposure of the bulb induced sprouting (Fig.…”

The proof is in the bulb: glycerol influences key stages of lily development

“…The common way of determining a bulb's size is by measuring its circumference. A circumference of at least 12 cm denotes ‘large’ bulbs, while less than 10 cm is considered ‘small’ (Lazare and Zaccai, ). In the past, bulbs were also sorted according to their weight (Blaney and Roberts, ; Roberts and Tomasovic, ; Wang and Gregg, ).…”

Overexpression of Lilium formosanum MADS-box (LFMADS) Causing Floral Defects While Promoting Flowering in Arabidopsis thaliana, Whereas Only Affecting Floral Transition Time in Nicotiana tabacum

“…L. formosanum , also known as the Formosa lily, with showy, trumpet-shaped flowers is closely related to the Easter lily, which displays a marked geographic cline and shows high resistance to drought, pathogens and climatic fluctuations [40]. Previous studies involved in regulating lily flowering time were mainly focused on the vernalization pathway [41,42,43,44] and photoperiod pathway [45,46]. Several genes have been identified in Liliaceae family and their potential biological functions related to the flowering time control, such as flowering locus T ( FT ) homologs LlFT in L. longiflorum [47], LfFT1 in L. x formolongi [48], and eight CONSTANS-LIKE ( COL ) family members ( LfCOLs ) in L. x formolongi .…”