DNA methylation dynamics and MET1a-like gene expression changes during stress-induced pollen reprogramming to embryogenesis

Abstract

Stress-induced plant cell reprogramming involves changes in global genome organization, being the epigenetic modifications key factors in the regulation of genome flexibility. DNA methylation, accomplished by DNA methyltransferases, constitutes a prominent epigenetic modification of the chromatin fibre which is locked in a transcriptionally inactive conformation. Changes in DNA methylation accompany the reorganization of the nuclear architecture during plant cell differentiation and proliferation. After a stress treatment, in vitro-cultured microspores are reprogrammed and change their gametophytic developmental pathway towards embryogenesis, the process constituting a useful system of reprogramming in isolated cells for applied and basic research. Gene expression driven by developmental and stress cues often depends on DNA methylation; however, global DNA methylation and genome-wide expression patterns relationship is still poorly understood. In this work, the dynamics of DNA methylation patterns in relation to nuclear architecture and the expression of BnMET1a-like DNA methyltransferase genes have been analysed during pollen development and pollen reprogramming to embryogenesis in Brassica napus L. by a multidisciplinary approach. Results showed an epigenetic reprogramming after microspore embryogenesis induction which involved a decrease of global DNA methylation and its nuclear redistribution with the change of developmental programme and the activation of cell proliferation, while DNA methylation increases with pollen and embryo differentiation in a cell-type-specific manner. Changes in the presence, abundance, and distribution of BnMET1a-like transcripts highly correlated with variations in DNA methylation. Mature zygotic and pollen embryos presented analogous patterns of DNA methylation and MET1a-like expression, providing new evidence of the similarities between both developmental embryogenic programmes.

Effect of n-butanol and cold pretreatment on the cytoskeleton and the ultrastructure of maize microspores when cultured in vitro

“…Although application of n-butanol following cold pretreatment did not elevated further the embryo/callus ratio, this combined treatment resulted in a higher number of responding microspores compared to cold treatment alone. These results suggest that cytoskeletal reorganization induces developmental program shift from the gametophytic to the sporophytic pathway, but gene expression changes or epigenetic alterations induced by cold stress (Solís et al 2012) ensure a more efficient induction of embryogenesis instead of generating callus.…”

Changes in DNA Methylation Levels and Nuclear Distribution Patterns after Microspore Reprogramming to Embryogenesis in Barley

“…There is increasing evidence that numerous processes of development and differentiation in both plants and animals are accompanied by chromatin remodeling [Kouzarides, 2007]. Stress-induced plant cell reprogramming involves changes in global genome organization, the epigenetic modifications being key factors of genome flexibility [Arnholdt-Schmitt, 2004;Solís et al, 2012].…”

“…The past decade revealed exciting findings on epigenetic mechanisms controlling developmental processes specific to flowering plants: the determination of the sporogenic fate during development, the differentiation of gametes within multicellular gametophytes, and the distinction of the 2 male gametes involved in double fertilization [Twell, 2011]. Recent studies have demonstrated epigenetic changes during plant developmental processes and after microspore induction to the sporophytic pathway leading to embryogenesis [Solís et al, 2012;Testillano et al, 2013]. However, the knowledge of the DNA methylation regulation during microspore embryogenesis is very limited.…”

“…Immunofluorescence Immunolocalization of 5-methyl-deoxycytidine (5mdC) was performed as previously described [Solís et al, 2012;. Historesin semithin sections were mounted on 3-aminopropyltriethoxysilane-coated slides, denatured with 2 N HCl for 45 min, washed in PBS and treated with 5% bovine serum albumin (BSA) in PBS for 10 min, incubated with anti-5mdC mouse antibody (Eurogentec) diluted 1: 50 in 1% BSA and Alexa-Fluor-488 anti-mouse IgG antibody (Molecular Probes) diluted 1: 25.…”

Calcium and cell wall dynamics during microspore embryogenesis and double haploid production in rapeseed and eggplant

“…These events include structural and cellular changes during the first divisions (Dubas et al 2011;Hause et al 1993;Satpute et al 2005;Telmer et al 1995;Zaki and Dickinson 1990), changes in DNA synthesis and gene expression (Binarova et al 1993;Boutilier et al 1994;Hays et al 1999;Seguí-Simarro et al 2011a), the role of epigenetic modifications Rodríguez-Sanz et al 2014;Solís et al 2012), regulatory cascades ( (Cordewener et al 2000;Cordewener et al 1994;Pechan et al 1991), with special focus on heat-shock proteins expression (Cordewener et al 1995;Seguí-Simarro et al 2003;Testillano et al 2000;Zhao et al 2003). Comparative studies between MDEs and zygotic embryos (Ilic-Grubor et al 1998;Yeung et al 1996) have shown that MDEs may hold a high morphologic similarity to zygotic embryos, and they can be used as a model to study general embryogenesis characteristics, as well as the role of different plant hormones during embryogenesis initiation and embryo development (Belmonte et al 2010;Hays et al 2001;Hays et al 2000;Hays et al 2002;Robert et al 2015).…”