ROS Homeostasis Regulates Somatic Embryogenesis via the Regulation of Auxin Signaling in Cotton

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.

Cross‐talk of Reactive Oxygen Species and Nitric Oxide in Various Processes of Plant Development

“…Regarding the hormonal interactions of H 2 O 2 , the salicylic acidtriggered embryogenesis was accompanied by H 2 O 2 production due to the inhibition of APX and CAT (Luo et al, 2001). In a recent proteomic study, several ROS-scavenging enzyme proteins were found to be induced in somatic embryos of cotton (Zhou et al, 2016). Suppressing the expression of specifically identified GhAPX proteins resulted in the inhibition of dedifferentiation, reflecting the involvement of ROS in the differentiation process.…”

Transcriptome Analysis of mRNA and miRNA in Somatic Embryos of Larix leptolepis Subjected to Hydrogen Treatment

“…Furthermore, exogenous hydrogen application significantly reduced ROS levels and enhanced antioxidant enzyme activity in H 2 -treated PEMs (Figure S1). Considering that redox status is a crucial factor in determining plant development [31] and ROS homeostasis regulates somatic embryogenesis [32], we presume that the increased rate of active pro-embryogenic cells and normal somatic embryos may be, at least partially, a result of reduced ROS levels after H 2 treatment.…”

GhL1L1 affects cell fate specification by regulating GhPIN1‐mediated auxin distribution

“…As an excellent natural provider of fibre, cotton needs a reproducible and highly efficient plant regeneration scheme for transgenic research and genetic engineering. The morphological and molecular mechanisms of SE have been studied in cotton in our laboratory (Jin et al, 2014;Yang et al, 2012;Zhou et al, 2016). GhHmgB3-deficient hypocotyls dedifferentiate more rapidly but fail to differentiate into ECs (Hu et al, 2011).…”

“…Auxin plays an important role in WUS expression, which is essential for embryonic stem cell fate determination during SE in Arabidopsis (Mayer et al, 1998;Su et al, 2009). Research has also demonstrated that the interactions between auxin, ethylene, gibberellic acid and stress response regulate SE (Wang et al, 2018;Zheng et al, 2013Zheng et al, , 2016Zhou et al, 2016).…”