Abstract
Somatic embryos are comparable to their zygotic counterparts for morphological traits but are derived from somatic cells through various metabolic regulations, collectively referred as somatic embryogenesis (SE). It has been well exploited for germplasm conservation, genetic engineering, mutation breeding, for artificial seed technology and as a tool for mass multiplication. Though somatic embryo development is an important area of interest in growth, and developmental studies, the underlying molecular mechanism remains unclear. Therefore, understanding the molecular basis behind somatic embryo development can provide insight into the signaling pathways integrating this process. Proteomic analysis of somatic embryo development in cv. Grand Naine (AAA) was carried out to identify the differentially expressed protein during somatic embryo development stages, using two dimensional gel electrophoresis together with mass spectrometry. In total, 25 protein spots were differentially expressed during sequential developmental stages of somatic embryos. Among these, three proteins were uniquely present in 30 days globular stage and six proteins in 60 days old mature somatic embryo. Functional annotation of identified spots showed that major proteins are involved in growth and developmental process (17%) followed by defense response (12%) and signal transportation events (12%). In the early stage, cell division and growth related proteins are involved in the induction of somatic embryos whereas in the late developmental stage, cell wall associated proteins along with stress related proteins played a defensive role against dehydration and osmotic stress and resulted in the maturation of somatic embryo. The identified stage specific proteins are valuable indicators and genetic markers for screening and for media manipulation to improve SE efficiency in recalcitrant crops and varieties.