Proteomic analyses of Oryza sativa mature pollen reveal novel proteins associated with pollen germination and tube growth

Authors

  • Shaojun Dai,

    1. Key Laboratory of Photosynthesis & Environmental Molecular Physiology, Research Center for Molecular & Developmental Biology, Institute of Botany, Chinese Academy of Sciences, Beijing, P. R. China
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  • Lei Li,

    1. Key Laboratory of Photosynthesis & Environmental Molecular Physiology, Research Center for Molecular & Developmental Biology, Institute of Botany, Chinese Academy of Sciences, Beijing, P. R. China
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  • Taotao Chen,

    1. Key Laboratory of Photosynthesis & Environmental Molecular Physiology, Research Center for Molecular & Developmental Biology, Institute of Botany, Chinese Academy of Sciences, Beijing, P. R. China
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  • Kang Chong,

    1. Key Laboratory of Photosynthesis & Environmental Molecular Physiology, Research Center for Molecular & Developmental Biology, Institute of Botany, Chinese Academy of Sciences, Beijing, P. R. China
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  • Yongbiao Xue,

    1. Key Laboratory of Molecular & Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, P. R. China
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  • Tai Wang Dr.

    Corresponding author
    1. Key Laboratory of Photosynthesis & Environmental Molecular Physiology, Research Center for Molecular & Developmental Biology, Institute of Botany, Chinese Academy of Sciences, Beijing, P. R. China
    • Key Laboratory of Photosynthesis & Environmental Molecular Physiology, Research Center for Molecular & Developmental Biology, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Haidianqu, Beijing 100093, P. R. China Fax: +86-10-62594170
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Abstract

As a highly reduced organism, pollen performs specialized functions to generate and carry sperm into the ovule by its polarily growing pollen tube. Yet the molecular genetic basis of these functions is poorly understood. Here, we identified 322 unique proteins, most of which were not reported previously to be in pollen, from mature pollen of Oryza sativa L. ssp japonica using a proteomic approach, 23% of them having more than one isoform. Functional classification reveals that an overrepresentation of the proteins was related to signal transduction (10%), wall remodeling and metabolism (11%), and protein synthesis, assembly and degradation (14%), as well as carbohydrate and energy metabolism (25%). Further, 11% of the identified proteins are functionally unknown and do not contain any conserved domain associated with known activities. These analyses also identified 5 novel proteins by de novo sequencing and revealed several important proteins, mainly involved in signal transduction (such as protein kinases, receptor kinase-interacting proteins, guanosine 5'-diphosphate dissociation inhibitors, C2 domain-containing proteins, cyclophilins), protein synthesis, assembly and degradation (such as prohibitin, mitochondrial processing peptidase, putative UFD1, AAA+ ATPase), and wall remodeling and metabolism (such as reversibly glycosylated polypeptides, cellulose synthase-like OsCsLF7). The study is the first close investigation, to our knowledge, of protein complement in mature pollen, and presents useful molecular information at the protein level to further understand the mechanisms underlying pollen germination and tube growth.

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