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Systemic delivery of si RNA in pumpkin by a plant PHLOEM SMALL RNA ‐ BINDING PROTEIN 1–ribonucleoprotein complex
Author(s) -
Ham ByungKook,
Li Gang,
Jia Weitao,
Leary Julie A.,
Lucas William J.
Publication year - 2014
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12662
Subject(s) - phloem , ribonucleoprotein , microbiology and biotechnology , rna , biology , rna binding protein , small interfering rna , small rna , phosphatase , biochemistry , phosphorylation , gene , botany
Summary In plants, the vascular system, specifically the phloem, functions in delivery of small RNA ( sRNA ) to exert epigenetic control over developmental and defense‐related processes. Although the importance of systemic sRNA delivery has been established, information is currently lacking concerning the nature of the protein machinery involved in this process. Here, we show that a PHLOEM SMALL‐RNA BINDING PROTEIN 1 (PSRP1) serves as the basis for formation of an sRNA ribonucleoprotein complex ( sRNPC ) that delivers sRNA (primarily 24 nt) to sink organs. Assembly of this complex is facilitated through PSRP1 phosphorylation by a phloem‐localized protein kinase, PSRPK1. During long‐distance transport, PSRP1– sRNPC is stable against phloem phosphatase activity. Within target tissues, phosphatase activity results in disassembly of PSRP1– sRNPC , a process that is probably required for unloading cargo sRNA into surrounding cells. These findings provide an insight into the mechanism involved in delivery of sRNA associated with systemic gene silencing in plants.