Abstract
Somatic embryogenesis (S.E.) is a versatile model for understanding the mechanisms of plant embryogenesis and a useful tool for plant propagation. To decipher the intricate molecular program and potentially to control the parameters affecting the frequency of S.E., a proteomics approach based on two-dimensional gel electrophoresis (2-DE) combined with MALDI-TOF/TOF was used. A total of 149 unique differentially expressed proteins (DEPs) were identified at different stages of cotton S.E. compared with the initial control (0 h explants). The expression profile and functional annotation of these DEPs revealed that S.E. activated stress-related proteins, including several reactive oxygen species (ROS)-scavenging enzymes. Proteins implicated in metabolic, developmental, and reproductive processes were also identified. Further experiments were performed to confirm the role of ROS-scavenging enzymes, suggesting the involvement of ROS homeostasis during S.E. in cotton. Suppressing the expression of specifically identified GhAPX proteins resulted in the inhibition of dedifferentiation. Accelerated redifferentiation was observed in the suppression lines of GhAPXs or GhGSTL3 in parallel with the alteration of endogenous ascorbate metabolism and accumulation of endogenous H2O2 content. Moreover, disrupting endogenous redox homeostasis through the application of high concentrations of DPI, H2O2, BSO, or GSH inhibited the dedifferentiation of cotton explants. Mild oxidation induced through BSO treatment facilitated the transition from embryogenic calluses (ECs) to somatic embryos. Meanwhile, auxin homeostasis was altered through the perturbation of ROS homeostasis by chemical treatments or suppression of ROS-scavenging proteins, along with the activating/suppressing the transcription of genes related to auxin transportation and signaling. These results show that stress responses are activated during S.E. and may regulate the ROS homeostasis by interacting with auxin signaling.
Highlights
C 2016 by The American Society for Biochemistry and Molecular Biology, Inc
The numbers of independent protein spots detected varied for different developmental stages, ranging from 838 to 1360 spots observed on 2-D gels
These results suggested that GhAPXs play important roles during S.E., and the alteration of S.E. process through ascorbate peroxidases (APX) suppression might be associated with the elevated endogenous H2O2 content
Summary
Citation for published item: Zhou, T. and Yang, X. and Guo, K. and Deng, J. and Xu, J. and Gao, W. and Lindsey, K. and Zhang, X. (2016) 'ROS homeostasis regulates somatic embryogenesis via the regulation of auxin signaling in cotton.', Molecular and cellular proteomics., 15 [6]. pp. 2108-2124. (2016) 'ROS homeostasis regulates somatic embryogenesis via the regulation of auxin signaling in cotton.', Molecular and cellular proteomics., 15 [6]. ROS Homeostasis Regulates Somatic Embryogenesis via the Regulation of Auxin Signaling in Cotton*□S. Perturbation of ROS homeostasis by chemical treatments or suppression of ROS-scavenging proteins, along with the activating/suppressing the transcription of genes related to auxin transportation and signaling. During somatic embryogenesis (S.E.), differentiated somatic cells reentering the cell cycle undergo dedifferentiation and redifferentiation, followed by the formation of embryogenic cells and somatic embryos, and eventually develop into new plants [1] Such developmental restructuring involves the orchestration of various signal networks and reprogramming gene expression patterns to alter the original development program [2, 3]. Data support the view that ROS homeostasis is crucial for initiating and maintaining dedifferentiation, while mild oxidative conditions promote redifferentiation, and there is an interplay between ROS and auxin homeostasis to modulate S.E. in cotton plants
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