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

Key Laboratory of Photosynthesis & Environmental Molecular Physiology, Research Center for Molecular & Developmental Biology, Institute of Botany, Chinese Academy of Sciences, Beijing, PR China.
PROTEOMICS (Impact Factor: 3.81). 04/2006; 6(8):2504-29. DOI: 10.1002/pmic.200401351
Source: PubMed


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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    • "Mature pollen exhibits a highly reduced, two or three celled structure that plays a key role in plant fertility and crop production. Mature pollen grains possess pre-synthesized proteins to facilitate the upcoming germination and fertilization events that are marked by hydration, cohesion, establishment of pollen tube polarity, pollen-stigma interaction and multiple downstream signaling processes [1]. In addition, pollen contains proteinaceous factors required for inter-and intracellular transport of metabolites or ions to complement the dynamic phase of pollen germination. "
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    • "All rights reserved. (Dai et al. 2006). The variation in the amounts of these proteins upon elevated NO 2 (Table 2) indicates that NO 2 affects cytoskeleton dynamics and male gametophyte development, which also agrees with the reduced pollen viability of several plant species upon in vitro exposure of the pollen to NO 2 (Cuinica et al. 2014). "
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    • "Consequently, comprehensive analysis on spatiotemporal expression profiles in plant reproductive tissues and related processes on transcriptomic and proteomic levels were performed in different species. It provided abundant transcriptomic and proteomic data about mature pollen or even haploid male gametophyte and germinated pollen or pollen tube [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34], matured pistil, and pollinated pistil [35] [36] [37] [38] [39] [40] [41] [42] [43]. However, these studies mainly focused on the quantitative changes of gene expression and were unable to provide any information on protein PTMs, such as phosphorylation. "
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