Embryogenic competence of microspores is associated with their ability to form a callosic, osmoprotective subintinal layer

Abstract

A reduced, genotype-dependent ability to form a protective subintinal layer that serves as osmoprotective barrier to increase viability is identified as a source of recalcitrance to induction of microspore embryogenesis.

Dynamic Changes in Arabinogalactan-Protein, Pectin, Xyloglucan and Xylan Composition of the Cell Wall During Microspore Embryogenesis in Brassica napus

“…We previously demonstrated that the subintinal layer and the first cell walls of embryogenic microspores are compositionally different from the intine of pollen-like structures and from conventional cell walls of mature MDEs in terms of callose and cellulose content (Parra-Vega et al, 2015b; Rivas-Sendra et al, 2019). Based on this, we herein investigated whether these differences are extensive to other cell wall components.…”

“…Our observations have relevant implications in the developmental fates of microspores undergoing them. This study adds to our previous studies focused on the ultrastructural changes occurring in the newly formed walls during the first stages of microspore embryogenesis (Parra-Vega et al, 2015b), and on the changes in calcium levels (Rivas-Sendra et al, 2017) and in callose and cellulose composition during induction of microspore embryogenesis (Rivas-Sendra et al, 2019). Together, these studies represent the most comprehensive and detailed work performed to date to investigate the changes in cell wall composition as a consequence of embryogenesis induction in B. napus microspores, and their implications in this developmental switch.…”

“…After cytokinesis, the newly formed inner walls are irregular, incomplete, and present large deposits of cytoplasmic material secreted to the apoplast (Corral-Martínez et al, 2013; Parra-Vega et al, 2015a,b). Beneath their original intine, embryogenic microspores develop an additional layer, the subintinal layer, which is absent in non-embryogenic cultured microspores (Parra-Vega et al, 2015b; Rivas-Sendra et al, 2019). In addition to their structure, the composition of newly formed walls is also different from that of conventional cell walls.…”

“…Primary cell walls are predominantly composed of cellulose, hemicellulose, pectin and structural glycoproteins (Cosgrove, 2005). In contrast, both subintinal layers and inner walls are callose-rich and cellulose-deficient during the first embryogenic stages (Parra-Vega et al, 2015b; Rivas-Sendra et al, 2019).…”

Live Imaging of embryogenic structures in Brassica napus microspore embryo cultures highlights the developmental plasticity of induced totipotent cells

“…Brassica napus is a well-studied model system for ME, in part due to the large number of responding genotypes that differ in the extent to which they are able to form haploid embryos (Bhowmik et al 2011 ). In B. napus ME has been used to study various aspects of (in vitro) embryo development, including totipotency (Joosen et al 2007 ; Malik et al 2007 ; Li et al 2014 ), cell wall architecture (El-Tantawy et al 2013 ; Solís et al 2016 ; Corral-Martínez et al 2019 ; Rivas-Sendra et al 2019 ), hormone signalling (Hays 2000 ; Dubas et al 2013 , 2014 ; Soriano et al 2014 ; Robert et al 2015 ; Rodríguez-Sanz et al 2015 ), and the role of the suspensor in patterning the embryo proper (Supena et al 2008 ; Soriano et al 2014 ).…”