Abscisic acid controls dormancy development and bulb formation in lily plantlets regenerated in vitro

Abstract

Plantlets of lily regenerated in vitro from scale explants consist of scales and leaves from which the base of the petiole has swollen to a scale. Fluridone, an inhibitor of ABA‐synthesis, applied during culture in vitro, inhibited the swelling of the petioles and promoted leaf formation. At high fluridone concentrations (10 or 33μM), swelling was completely blocked, and plantlets consisted of leaves only. Addition of ABA during the regeneration in vitro had the opposite effect and resulted in plantlets with scales only. When applied simultaneously with fluridone, ABA nullified the effect of fluridone. This demonstrates that bulb formation in lily is under the control of ABA. Lily plantlets regenerated in vitro on scale explants at 20 or 25°C were harvested after 11 weeks, and the leaves were removed from the bulblets. The bulblets were dormant and required a cold treatment to achieve rapid emergence after planting in soil. Fluridone added during the culture in vitro prevented the development of dormancy, and the bulblets did not require a cold treatment. The effect of fluridone was nullified by simultaneous addition of ABA. Bulblets harvested after 6 weeks of culture at 20°C had not yet developed dormancy. Bulblets regenerated at 15°C were only slightly dormant. In both types of bulblets, it is unlikely that the lack of dormancy was due to low ABA‐levels since addition of ABA did not affect the dormancy status. These data indicate that the level of endogenous ABA and an unknown additional factor play major roles in the development of dormancy.

In vitro regeneration and bulblet growth from lily bulbscale explants as affected by retardants, sucrose and irradiance

“…There are reports demonstrating the role of ABA in bulb formation in Lilium (Klerk 1992, Kim et al 1994. Also, role of P 333 in enhancing bulblet formation has earlier been reported (Klerk 1992, Thakur et al 2002.…”

Dormancy development during cold hardening of in vitro cultured Malus domestica Borkh. plants in relation to their frost resistance and cryotolerance

“…Endodormancy, a part of dormancy, refers to a state of buds regulated by internal factors where growth is possible only after plants have been exposed to sufficient amount of chilling (Lang et al 1987;Welling and Palva 2006). Dormancy of in vitro plants has been frequently studied on bulb plant species (Maksimović et al 2008;Kwang-Soo Kim et al 1994;Aguettaz et al 1990;Delvallée et al 1990). Some investigations of partial aspects related to endodormancy were made on fruit trees in vitro but there is a lack of studies for the investigation of dormancy induction and release in trees in vitro.…”

ABA contents and the regeneration ability of Fritillaria imperialis L. cultured in vitro

“…The initiation of hyacinth bulblet formation in vitro and their growth was inhibited by ABA (Pierik and Steegmans 1975). Kim et al (1994) demonstrated that in lily cultured in vitro an inhibition of ABA synthesis by fluridone gave plantlets consisting solely of leaves while the presence of ABA induced bulb formation with scales only. Work is now in progress in order to precise the hormonal regulation of the regeneration pattern in fritillary.…”