Insights into the conversion potential of Theobroma cacao L. somatic embryos using quantitative proteomic analysis

Abstract

Somatic embryogenesis (SE) has been routinely used as mass micropropagation technique, and as a model system for investigating the structural, physiological, and molecular events occurring during somatic embryo development. Successful in vitro SE is related to the quality and yield of somatic embryos obtained. In cacao (Theobroma cacao L.) SE, the efficiency of somatic embryo production has improved with secondary SE. However, the low number of somatic embryos able to conversion into viable plantlets is still low. Then, two morphological types of normal mature somatic embryos can be identified during cacao secondary SE. The first type shows white appearance and high conversion potential (75%), while the second type shows translucent appearance and exhibit low conversion potential (15%). In order to investigate the proteins that can be associated to conversion potential in cacao somatic embryos, the mass spectrometry HDMS E proteomic approach was used. At least 60 proteins showed differences in abundance levels in cacao white somatic embryos, when compared to translucent. An increased abundance of Beta-glucosidase, NAD(P)-linked oxidoreductase and Electron transfer flavoprotein proteins were observed in white somatic embryos. Moreover, in translucent somatic embryos were observed an increased abundance of Cytochrome P450 and Pathogenesis-related proteins. Using white somatic embryos as a model, we suggest that carbohydrate metabolism process and the redox regulation are involved in the control/regulation of somatic embryo quality. These new findings may improve cacao SE protocol, as well as the understanding of the role of pivotal metabolic pathways associated to this in vitro morphogenetic route.

Signaling Overview of Plant Somatic Embryogenesis

“…Although there is a morphological resemblance between somatic and zygotic embryos, their development is distinctive based on plant classification (angiosperms and gymnosperms). It is considered that zygotic embryos are nourished via the phloem tissue, whereas somatic embryos use an exogenous supply of carbohydrates and their morphological stages occur without vascular tissue connection (Pila Quinga et al, 2018).…”

“…The first is at a morphogenetic level, where the meristem activity is triggered at a physiological level and the process of growth, storage and maturation is initiated. The second is a metabolic stage that is characterized by biochemical activities and the preparation for desiccation to complete the seed formation process (Harada and Kwong, 2002; Pila Quinga et al, 2018). In this last phase, somatic embryos achieve both morphological and physiological maturity, which guarantees satisfactory post-embryonic performance.…”

Global scale transcriptome analysis reveals differentially expressed genes involve in early somatic embryogenesis in Dimocarpus longan Lour

“…Over the last few years, the expression profiles of SE related genes and other differentially expressed genes during SE had been extensively excavated by RNA-seq sequencing in various species, including Gossypium hirsutum [9–12], Arabidopsis [13, 14], Maize [15], Norway spruce [16, 17], Coconut plam [18], Brazilian pine [19], Eleutherococcus senticosusk [20], Camphor tree [21], Strawberry [22], Rice [23], Lilium pumilum [24], Mangosteen [25], Papaya [26], and Triticum aestivum [27]. Meanwhile, the comparative proteome analysis during SE also characterized numerous proteins that associated with SE in many plant species, such as Maize [28], Papaya [29], Cacao [30], Sugarcane [31], Musa . spp.…”

AUXIN PULSE IN THE INDUCTION OF SOMATIC EMBRYOS OF Eucalyptus

“…Also in the histochemical test with Ruthenium Red, the accumulation of oil droplets inside cells located in the peripheral region of the somatic proembryo was observed in some embryogenic calli. These droplets of oil may be used by somatic proembryos as reserve substances, since in dicotyledons mainly lipids and proteins are found as initial sources of reserve (Rocha et al, 2012) essential for somatic embryos because they do not have a connection with maternal tissue (Pila Quinga et al, 2018).…”