Putrescine induces somatic embryo development and proteomic changes in embryogenic callus of sugarcane.

Somatic embryogenesis, an important biotechnological technique, has great potential for application in sugarcane breeding and micropropagation. Polyamines have been associated with the regulation of several physiological processes, including the acquisition of embryogenic competence and somatic embryogenesis. In this study, we used a proteomic approach to evaluate the effects of exogenous polyamine on sugarcane somatic embryo development to better understand this process. Embryogenic cultures were treated with different concentrations of putrescine, spermidine, and spermine. Proteomic analyses combined the shotgun method and the nanoESI-HDMS(E) technology. Among polyamines, 500 µM putrescine gave rise to the highest number of somatic embryos; however, no differences in the amount of fresh matter were observed between polyamines and control. Differences in protein abundance profiles resulting from the effect of 500 µM putrescine on sugarcane somatic embryo maturation were observed. Proteomic analyses of putrescine and control treatment showed differences in the abundances of proteins related to somatic embryogenesis, such as arabinogalactan proteins, peroxidases, heat shock proteins, glutathione s-transferases, late embryogenesis abundant proteins, and 14-3-3 proteins. These results show that putrescine and the identified proteins play important roles in protecting the cells against an in vitro stress environment, contributing to the formation of somatic embryos during the maturation treatment. BIOLOGICAL SIGNIFICANCE: Despite all studies with somatic embryogenesis, the molecular mechanisms controlling the process have not been completely understood. In this study, we highlighted the effects of the polyamine putrescine on somatic embryogenesis of sugarcane and the differentially abundant proteins related to somatic embryo development. We identified six groups of important stress related proteins that are involved in the adaptation of cells to the stress environment of in vitro culture and may also be part of the mechanisms associated to the somatic embryogenesis process. Therefore, our research is trying to understand the complexity of how one single somatic cell becomes a whole plant.

Comparative proteomic analysis of somatic embryo maturation in Carica papaya L.

BACKGROUND: Somatic embryogenesis is a complex process regulated by numerous factors. The identification of proteins that are differentially expressed during plant development could result in the development of molecular markers of plant metabolism and provide information contributing to the monitoring and understanding of different biological responses. In addition, the identification of molecular markers could lead to the optimization of protocols allowing the use of biotechnology for papaya propagation and reproduction. This work aimed to investigate the effects of polyethylene glycol (PEG) on somatic embryo development and the protein expression profile during somatic embryo maturation in papaya (Carica papaya L.). RESULTS: The maturation treatment supplemented with 6% PEG (PEG6) resulted in the greatest number of somatic embryos and induced differential protein expression compared with cultures grown under the control treatment. Among 135 spots selected for MS/MS analysis, 76 spots were successfully identified, 38 of which were common to both treatments, while 14 spots were unique to the control treatment, and 24 spots were unique to the PEG6 treatment. The identified proteins were assigned to seven categories or were unclassified. The most representative class of proteins observed in the control treatment was associated with the stress response (25.8%), while those under PEG6 treatment were carbohydrate and energy metabolism (18.4%) and the stress response (18.4%). CONCLUSIONS: The differential expression of three proteins (enolase, esterase and ADH3) induced by PEG6 treatment could play an important role in maturation, and these proteins could be characterized as candidate biomarkers of somatic embryogenesis in papaya.