Proteomic analyses of somatic and zygotic embryos of Cyclamen persicum Mill. reveal new insights into seed and germination physiology

Abstract

In the horticulturally important ornamental species Cyclamen persicum Mill., somatic embryogenesis is an efficient vegetative propagation method and the development of artificial seeds is an ultimate aim. This study aims at a systematic comparison of the proteomes of zygotic embryos, somatic embryos grown in liquid medium containing 30 or 60 g l(-1) sucrose, germinating embryos of both types and endosperm in order to obtain novel insights into seed and germination physiology. Using high resolution two-dimensional isoelectric focussing/sodium dodecylsulfate polyacrylamide gel electrophoresis (2D IEF/SDS PAGE), 74% of the proteins expressed in zygotic embryos were found in similar abundance in somatic embryos grown in 60 g l(-1) sucrose. Somatic embryos grown in 30 g l(-1) sucrose accumulated fewer protein species than those grown in 60 g l(-1). Selected proteins were identified following mass spectrometry (nano-LC-MS/MS). Four enzymes involved in glycolysis (UDP-glucose pyrophosphorylase, fructose bisphosphate aldolase, triosephosphate isomerase and glyceraldehyde-3-phosphate dehydrogenase GAPDH) were specifically induced in somatic embryos. 11S globulin proteins identified by MS were present in high levels in somatic embryos, zygotic embryos and endosperm, whereas 7S globulins were detected mainly in endosperm and zygotic embryos. These are the first storage proteins identified in C. persicum. Xyloglucans are known to be another group of seed storage compounds in C. persicum. Interestingly, xyloglucan endotransglycosylases were found to be highly expressed in endosperm tissue. We discuss the physiological implications of these observations.

The Current Status of Proteomic Studies in Somatic Embryogenesis

“…7.3) (Balbuena et al 2009;Thorpe 1995). Clearly, in ZE, storage proteins and other storage molecules (small enolases, oligosaccharides, and lipids) are key factors that provide energy to the seedling until the establishment of photosynthesis (Winkelmann et al 2006;Rode et al 2011). Therefore, increasing the availability of storage molecules in somatic embryos could improve conditions and promote the generation of high quality in vitro plantlets.…”

“…These studies have been followed up with the focused identification of key proteins associated with each stage of the transdifferentiation of somatic embryos (Rode et al 2012;Bian et al 2010;Vale Ede et al 2014). Moreover, the morphological and physiological similarities between zygotic and somatic embryogenesis have suggested similar biochemical status for cells undergoing both of these processes, and protein profiles for zygotic and somatic embryogenesis have been compared in a few plants species (Sghaier-Hammami et al 2009;Winkelmann et al 2006;Noah et al 2013). Altogether, the proteins identified in several conditions and stages of SE reflect the biochemical status of cells.…”

Molecular aspects of somatic-to-embryogenic transition in plants

“…DNA methylation is a unique and noteworthy process because it involves the covalent modification of a cell's genetic material [54,94] and plays an important role to modify the information content of the underlying genetic sequence and gene expression [8]. Xiao et al [221] show that DNA methylation performed by MET1 influences gene expression during embryogenesis in Arabidopsis. Therefore, dynamic changes in chromatin structure by DNA methylation at presence of 2,4-D leads to genomic reprogramming in somatic cells and hundreds of genes specifically required for acquiring the embryogenic competence are expressed (Fig.…”

Dynamics of physiological and biochemical changes during somatic embryogenesis of Acca sellowiana

“…Accumulating evidence suggests that the patterns of protein synthesis during development of zygotic embryos are recapitulated during somatic embryogenesis (Winkelmann et al 2006). The accumulation of proteins (total) is associated with embryo development and maturation through regulation of cell expansion and other biochemical and biophysical features (Jiménez 2001).…”