Gene expression during early somatic embryogenesis in Brazilian pine (Araucaria angustifolia (Bert) O. Ktze)

Abstract

Brazilian pine (Araucaria angustifolia (Bert) O. Ktze) is the only native conifer species with economic importance in Brazil. Recently, due to intensive exploitation Brazilian pine was included in the official list of endangered Brazilian plants, under the ''vulnerable'' category. Biotechnology tools like somatic embryogenesis (SE) are potentially useful for mass clonal propagation and ex situ conservation strategies of commercial and endangered plant species. In spite of that, numerous obstacles still hamper the full application of SE technology for a wider range of species, including Brazilian pine. To enhance somatic embryogenesis in Brazilian pine and to gain a better understanding of the molecular events associated with somatic embryo development, we analyzed the steady-state transcript levels of genes known to regulate somatic embryogenesis using semiquantitative reverse transcription polymerase chain reaction (sqRT-PCR). These genes included Argonaute (AaAGO), Cup-shaped cotyledon1 (AaCUC), wushel-related WOX (AaWOX), a S-locus lectin protein kinase (AaLecK), Scarecrow-like (AaSCR), Vicilin 7S (AaVIC), Leafy Cotyledon 1 (AaLEC), and a Reversible glycosylated polypeptide (AaRGP). Expression patterns of these selected genes were investigated in embryogenic cultures undergoing different stages of embryogenesis, and all the way to maturation. Up-regulation of AaAGO, AaCUC, AaWOX, AaLecK, and AaVIC was observed during transition of somatic embryos from stage I to stage II. During the maintenance phase of somatic embryogenesis, expression of AaAGO and AaSCR, but not AaRPG and AaLEC genes was influenced by presence/absence of plant growth regulators, both auxins and cytokinins. The results presented here provide new insights on the molecular mechanisms responsible for somatic embryo formation, and how selected genes may be used as molecular markers for Brazilian pine embryogenesis.

Quantitative proteomic analysis of Araucaria angustifolia (Bertol.) Kuntze cell lines with contrasting embryogenic potential

“…Although SE protocols have been developed for a number of species [1,2,4], the limitations imposed by suboptimal conditions during in vitro growth of somatic embryos have restricted its use in others [5]. The establishment of a successful SE protocol requires the development of molecular markers that can be used to select cell lines with highly embryogenic potential [6,7]. Conservation strategies based on SE associated with cryopreservation are being developed for Araucaria angustifolia, an endangered conifer that is native to Brazil [7,8].…”

“…Conservation strategies based on SE associated with cryopreservation are being developed for Araucaria angustifolia, an endangered conifer that is native to Brazil [7,8]. SE induction in A. angustifolia was first described by [9], and since then several reports have outlined attempts to develop a SE protocol for this species, but to date successful plant regeneration has not been possible [6,7,10].…”

Time-lapse cell tracking reveals morphohistological features in somatic embryogenesis of Araucaria angustifolia (Bert) O. Kuntze

“…In the sequence, pro-embryos and globular-staged somatic embryos were obtained in response to the inclusion of osmotic agents in the culture medium, but independent on application of ABA (Santos et al , 2008Silveira et al 2002;Steiner et al 2005;Vieira et al 2012). Recently, it was reported in the maturation phase the use of osmotic agents, AC, and 120 lM ABA (Schlögl et al 2012). Jo et al (2013) proposed the inclusion of maturation phase I, consisting of culture medium with osmotic agents and AC for 30 days followed by maturation phase II, with AC and 120 lM ABA.…”

Genes and Trans-Factors Underlying Embryogenic Transition in Plant Soma-Cells

“…Work done so far in this area suggested that reprogramming of cellular fate is due to pattern change in the expression of candidate genic-factors in response to diverse stress conditions. Such important factors may in turn trigger the cellular modulation for embryo formation (Feher et al 2003 ;Chugh and Khurana 2002 ;Ge et al 2012 ;Namasivayam 2007 ;Rose and Nolan 2006 ;Schlögl et al 2012 ;Wiśniewskaa et al 2012 ;Wójcikowska et al 2013 ;Xu et al 2013 ;Zheng et al 2013 ). It is evident that phytohormones' level is critical for the induction of SE under stress conditions, which subsequently may infl uence genetic and cellular trans -factors essential for cell-restructuring and re-programming.…”