Storage protein gene expression in zygotic and somatic embryos of interior spruce

Abstract

Storage protein gene expression was compared between zygotic and somatic embryos of interior spruce (Picea glauca/engelmanii complex). Somatic embryos, grown on medium containing 40 μM or 10 μM abscisic acid (ABA), and zygotic embryos accumulated IIS legumin, 7S vicilin and 2S albumin storage proteins. Zygotic embryos displayed a rapid, transient period of storage protein accumulation, while somatic embryos differentiated on 40 μM ABA displayed a more prolonged, gradual accumulation, with some accumulation still evident after 9 weeks of maturation. Somatic embryos on 10 μM ABA accumulated storage proteins initially, but these were rapidly degraded as the embryos germinated precociously. Legumin, albumin and vicilin transcripts were detectable in torpedo stage zygotic and somatic embryos, and increased during embryo development. Transcript levels in zygotic embryos increased during cotyledon development, but following maximum dry weight accumulation and moisture loss, transcripts declined rapidly to low levels. In contrast, somatic embryos on 40 μM ABA had high transcript levels for a prolonged period. These levels were still present after 9 weeks of maturation. A decline in storage protein transcripts similar to zygotic embryos was apparent following a mild drying treatment. These results suggest that a decline in storage protein transcripts is stimulated by embryo drying during the later stages of conifer embryogenesis. Low levels of storage protein transcripts also appeared in somatic embryos on 10 μM ABA, but declined during precocious germination. Osmotic stress induced storage protein and storage protein transcript accumulation. This could be partially inhibited by inclusion of the ABA biosynthetic inhibitor, fluridone. However, endogenous ABA levels did not differ significantly between embryos cultured in the presence or absence of fluridone.

Storage protein dynamics in zygotic and somatic embryos of white fir

“…A conspicuous increase in synthesis of the 43 kDa protein took place in megagametophyte at the beginning of July preceding its synthesis in embryos by 2-3 weeks. This coincides also with the period of the most dramatic changes in protein accumulation observed in Pseudotsuga menziesii (Misra, 1993), Picea glauca (Flinn et al, 1991(Flinn et al, , 1993 and Picea abies (Hakman, 1993). We may only speculate whether the 23-24 kDa components whose synthesis started only in the cotyledonary embryos belong to the category of the late embryogenesis abundant proteins.…”

Morphogenic Aspects of Somatic Embryogenesis

“…In support of this, the application of ABA to microspore-derived rapeseed embryos stimulated storage protein transcript accumulation [208] and promoted the correct developmental induction of storage protein transcripts to levels comparable to equivalent stage zygotic embryos [211]. Developing Norway and interior spruce somatic embryos matured on ABA displayed storage protein levels similar to those of zygotic embryos [202,215,216], with similar developmental patterns of storage protein transcript appearance [217] and protein accumulation [202,217], as developing zygotic embryos. Furthermore, reduced levels of ABA resulted in lower levels of storage protein accumulation [166].…”

“…In addition to ABA, osmoticum plays a role in obtaining correct storage protein expression in developing somatic embryos. The application of 13-20% mannitol alone could replace 40 J-tM ABA during the later stages of interior spruce embryo maturation, preventing precocious germination and allowing storage protein accumulation [196,217]. A similar stimulation of storage protein transcript accumulation by sorbitol was observed in rapeseed microspore-derived embryos [211].…”

Efeito do frio sobre os carboidratos solúveis em culturas embriogênicas de Acca sellowiana O. Berg (Myrtaceae)

“…O acúmulo adequado de reservas como carboidratos solúveis, amido e proteínas afeta de forma especial a embriogênese somática, sendo crucial para a retomada do desenvolvimento após a obtenção de embriões cotiledonares (Attree et al 1992, Flinn et al 1993, Chanprame et al 1998. Devido às múltiplas funções que os açúcares desempenham nas células, incluindo transporte, fornecimento de energia e de esqueletos carbônicos e regulação do potencial osmótico e da expressão gênica, o metabolismo dos carboidratos solúveis representa um dos mais importantes processos no ciclo celular (Carrier et al 1999).…”