Abscisic acid and indole‐3‐butyric acid regulation of maturation and accumulation of storage proteins in somatic embryos of interior spruce

Abstract

The ontogenetic course followed by somatic embryos of interior spruce is highly dependent on the media concentration of abscisic acid (ABA). Little or no organized development occurs in the absence of ABA and as the level of ABA is increased, a range of embryo types is produced. “Shooty embryo” structures predominate in many callus lines at low levels of ABA (1‐10 μM), while 10‐20 μM ABA promotes the formation of bipolar embryos that germinate precociously. When ABA is increased to 30‐40 μM, precocious germination is inhibited and opaque cotyledonary embryos characteristic of their zygotic counterparts are formed which enter a period of quiescence. Only “mature” somatic embryos contain significant amounts of storage proteins and the level to which these proteins accumulate is dependent on the concentration of ABA. Indole‐butyric acid (IBA) included with ABA increases the number of mature embryos. Root elongation, which was used as a measure of embryo quality, was never observed from shooty embryo Structures and was 2‐3 fold higher in mature embryos compared to those that germinated precociously.

Somatic Embryogenesis and Efficient Plant Regeneration in Japanese Cypresses

“…The higher the ABA concentration, the greater the number of mature embryos. A similar result was reported in Pinus strobus (Klimaszewska and Smith, 1997), Picea glauca-engelmannii complex (Roberts et al, 1990a), and P. glauca . The addition of AC into the media notably enhanced the maturation efficiency, with around a 4-fold enhancement achieved by using 33.3 to 100 µM in combination with 2 gL -1 AC.…”

“…Somatic embryos of the hybrid larch (Larix x leptoeuropaea) developed normally on a medium supplemented with 60 µM ABA, but abnormally on a medium with no ABA (Gutmann et al, 1996). Most of the studies on somatic embryogenesis in conifers have reported ABA as a key hormone in embryo development and that the number and quality of embryo produced was vastly reduced in its absence (Durzan and Gupta, 1987;von Arnold and Hakman, 1988;Hakman and von Arnold, 1988;Attree and Fowke, 1993;Dunstan et al, 1998 Several authors have suggested that the role of ABA in somatic embryogenesis is to inhibit cleavage polyembryony with the consequent development of individual somatic embryos (Durzan and Gupta, 1987;Boulay et al, 1988;Krogstrup et al, 1988;Gupta et al, 1991), to stimulate the accumulation of nutrients, lipids, proteins, and carbohydrates , and suppress precocious germination (Roberts et al, 1990a). In addition, Gupta et al (1993) reported improved desiccation tolerance to less than 10% water content with 80 to 90% germination rates in Norway spruce embryos produced with a combination of ABA and AC.…”

“…1L). The beneficial effect of PEG on embryo maturation may be related to a water stress induction similar to that generated by desiccation , to an increase in the accumulation of storage reserves, such as storage proteins, lipids, and polypeptides (Roberts et al, 1990a;Attree et al, 1992;Misra et al, 1993), and to a tolerance to water loss (Attree et al, 1991).…”

High frequency somatic embryogenesis and plant regeneration from zygotic embryo-derived callus cultures of three Allium species

“…These observations would suggest that development and germination of somatic embryos is promoted by ABA. Stimulation of the development of somatic embryos by ABA has recently been observed in a variety of species including Brassica, Datura, Nicotiana (Sethi et al 1990), Hordeum (Rengel & Jelaska 1986), Picea (Dunstan et al 1988;Roberts et al 1990)), Pinus (Sen et al 1989), Medicago (Fujii et al 1990) and Triticum (Brown et al 1989;Qureshi et al 1989). There is growing evidence that ABA directly controls the gene expression of embryogenesis proteins (e.g.…”

“…The effect of abscisic acid (ABA) on somatic embryo production and plant regeneration was studied because this plant growth regulator has been shown to have a promotive effect on somatic embryo development and maturation (e.g. Dunstan et al 1988;Brown et al 1989;Qureshi et al 1989;Fujii et al 1990;Roberts et al 1990) and shoot regeneration (Rengel & Jelaska 1986;Qureshi et al 1989;Sen et al 1989;Sethi et al 1990) for a range of species.…”