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Endogenous ABA content in relation to maturation of somatic embryos in Tulipa (L.) ‘Apeldoorn’ cultures

Maślanka, Małgorzata, Bach, Anna, Janowiak, Franciszek
Acta physiologiae plantarum 2016 v.38 no.11 pp. 270
Tulipa, abscisic acid, embryogenesis, enzyme-linked immunosorbent assay, fluridone, naphthaleneacetic acid, picloram, plantlets, shoots, somatic embryos
The aim of the present study was to estimate the endogenous abscisic acid (ABA) content in tulip ‘Apeldoorn’ torpedo and mature somatic embryos. Moreover, the effect of exogenous ABA and/or its inhibitor fluridone on somatic embryo maturation and conversion into plantlets was investigated. Torpedo-stage somatic embryos were subcultured on media containing 5 μM of picloram and 1 μM of 6-benzyl-aminopurine (BAP)—control, and combinations of ABA (0 or 10 μM) and/or fluridone (0 or 30 μM) for 1 week. Then, the torpedo embryos were transferred to a maturation medium containing 0.25 μM of α-naphthaleneacetic acid (NAA) and 2.5 μM of BAP, without ABA and fluridone treatment, and cultivated under darkness or light for ten weeks. Endogenous ABA content (first time measured in tulip somatic embryos) was evaluated by ELISA test. The obtained results revealed that the highest level of endogenous ABA, at 17.45 nmol g⁻¹ dry weight (DW), was recorded in torpedo-stage of tulip embryo development, only after 1 week of ABA treatment, and was nearly 10 times higher in comparison with the control. Simultaneous addition of ABA and fluridone to the medium resulted in the lowering of the ABA concentration to 9.58 nmol g⁻¹ DW. During ten weeks of maturation of the embryos, the endogenous ABA content in mature tissue of tulip somatic embryo considerably decreased to an amount 0.87–1.33 nmol g⁻¹ DW (irrespective of ABA and fluridone treatment) and did not differ significantly from control (0.59 nmol g⁻¹ DW). Exogenous ABA and fluridone significantly decreased the growth value of fresh weight (FW) of the tulip torpedo-shaped and mature embryos under light conditions. Percentage of the DW of the torpedo embryos treated with exogenous ABA was significantly higher (15.43–17.02) in comparison with the control (10.87). Three to three and a half times more malformed mature embryos were noted under light conditions than in darkness, irrespective of ABA and fluridone treatment. The highest percentage of mature embryos forming shoots (conversion) was observed under light conditions in the control and after fluridone treatment (26 and 20%, respectively).