Characterization and Expression Analysis of Medicago truncatula ROP GTPase Family during the Early Stage of Symbiosis

Authors

  • Wei Liu,

    1. National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, the Chinese Academy of Sciences, Shanghai 200032, China
    2. The Key Oasis Eco-agriculture Laboratory of Xinjiang Production and Construction Group, Shihezi University, Shihezi 832003, China
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  • Ai-Min Chen,

    1. National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, the Chinese Academy of Sciences, Shanghai 200032, China
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  • Li Luo,

    1. National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, the Chinese Academy of Sciences, Shanghai 200032, China
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  • Jie Sun,

    1. The Key Oasis Eco-agriculture Laboratory of Xinjiang Production and Construction Group, Shihezi University, Shihezi 832003, China
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  • Lian-Pu Cao,

    1. The Key Oasis Eco-agriculture Laboratory of Xinjiang Production and Construction Group, Shihezi University, Shihezi 832003, China
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  • Guan-Qiao Yu,

    1. National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, the Chinese Academy of Sciences, Shanghai 200032, China
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  • Jia-Bi Zhu,

    1. National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, the Chinese Academy of Sciences, Shanghai 200032, China
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  • Yan-Zhang Wang

    Corresponding author
    1. National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, the Chinese Academy of Sciences, Shanghai 200032, China
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Corresponding author
Tel: +86 21 5492 4167; Fax: +86 21 5492 4015; E-mail: yzwang@sippe.ac.cn

Abstract

ROPs (Rho-related GTPases of plants) are small GTPases that are plant-specific signaling proteins. They act as molecular switches in a variety of developmental processes. In this study, seven cDNA clones coding for ROP GTPases have been isolated in Medicago truncatula, and conserved and divergent domains are identified in these predicted MtROP proteins. Phylogenetic analysis has indicated that MtROPs are distributed into groups II, III, IV but group I. MtROP genes are expressed in various tissues at different levels. A quantitative reverse transcription PCR analysis indicated that these MtROP genes have different expression profiles in the roots in response to infection with rhizobia. The expression of MtROP3, MtROP5 and MtROP6 are increased, as the expression of Nod factor or rhizobial-induced marker genes—NFP, Rip1 and Enod11; MtROP10 has showed enhanced expression at a certain post-inoculation time point. No significant changes in MtROP7 and MtROP9 expression have been detected and MtROP8 expression is dramatically decreased by about 80%–90%. Additionally, ROP promoter-GUS analysis has showed that MtROP3, MtROP5 and MtROP6 have elevated expression in transgenic root hairs after rhizobial inoculation. These results might suggest a role for some ROP GTPases in the regulation of early stages during rhizobial infection in symbiosis.

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