title: Proteomic analysis reveals growth inhibition of soybean roots by manganese toxicity is associated with alteration of cell wall structure and lignification.
abstract: Plant roots, the hidden half of plants, play a vital role in manganese (Mn) toxicity tolerance. However, molecular mechanisms underlying root adaptation to Mn toxicity remain largely unknown. In this study, soybean (Glycine max) was used to investigate alterations of root morphology and protein profiles in response to Mn toxicity. Results showed that soybean root growth was significantly inhibited by Mn toxicity. Subsequent proteomic analysis revealed that 31 proteins were successfully identified via MALDI TOF/TOF MS analysis including 21 unique up-regulated and 6 unique down-regulated proteins, which are mainly related to cell wall metabolism, protein metabolism and signal transduction. qRT-PCR analysis revealed that corresponding gene transcription patterns were correlated with accumulation of 14 of 21 up-regulated proteins, but only 1 of 6 down-regulated proteins, suggesting that most excess Mn up-regulated proteins are controlled at the transcriptional levels, while down-regulated proteins are controlled at the post-transcriptional levels. Furthermore, changes in abundances of GTP-binding nuclear protein Ran-3, expansin-like B1-like protein, dirigent protein and peroxidase 5-like protein strongly suggested that alteration of root cell wall structure and lignification might be associated with inhibited root growth. Taken together, this study was helpful to further understandings of adaptive strategies of legume roots to Mn toxicity.
  
  
  
  This study highlighted the effects of Mn toxicity on soybean root growth and its proteome profiles. Excess Mn treatments inhibited root growth. Comparative proteomic analysis was performed to analyze the changes in protein profiles of soybean roots in response to Mn toxicity. A total of 31 root proteins with differential abundances were identified and predominantly associated with signal transduction and cell wall metabolism. Among them, the abundances of the GTP-binding nuclear protein Ran-3 and Ran-binding protein 1 were significantly increased, suggesting that the proteins could be involved in the signaling network in soybean roots responsive to Mn toxicity. Interestingly, three 14-3-3 proteins were decreased by excess Mn at protein but not mRNA levels, suggesting that these proteins could be regulated at post-transcriptional modification under Mn excess conditions. Furthermore, changes in abundances of expansin-like B1-like protein, peroxidase 5-like protein, dirigent protein 2-like protein and dirigent protein strongly suggested that Mn toxicity could influence root cell wall modification, and thus inhibit root growth. This study provided significant insights into the potential molecular mechanisms underlying soybean root adaptation to Mn toxicity, which was mainly through alteration of root cell wall structure and lignification.
authors.affiliation: Root Biology Center, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China; Institute of Tropical Crop Genetic Resources, Chinese Academy of Tropical Agriculture Sciences, Haikou 571101, China.
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Root Biology Center, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China; Institute of Tropical and Subtropical Cash Crops, Yunnan Academy of Agricultural Sciences, Baoshan 678000, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Yan
authors.affiliation: Root Biology Center, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China; Root Biology Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350000, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Sun
authors.affiliation: Root Biology Center, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China. Electronic address: jtian@scau.edu.cn.
authors.forename: Jiang
authors.initials: J
authors.lastname: Tian
authors.affiliation: Root Biology Center, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China; Root Biology Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350000, China. Electronic address: hliao@scau.edu.cn.
authors.forename: Hong
authors.initials: H
authors.lastname: Liao
mesh_terms: D000222:Adaptation, Physiological; D002473:Cell Wall / Q000187:drug effects / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D017705:Lignans / Q000378:metabolism; D008345:Manganese / Q000633:toxicity*; D018517:Plant Roots / Q000254:growth & development*; D020543:Proteome / Q000032:analysis*; D040901:Proteomics / Q000379:methods; D013025:Glycine max / Q000737:chemistry* / Q000187:drug effects / Q000254:growth & development; D013312:Stress, Physiological / Q000187:drug effects
chemical_list: D017705:Lignans; D020543:Proteome; D008345:Manganese
keywords: Mn toxicity; Proteomic analysis; Root; Soybean