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ARS Home » Research » Publications at this Location » Publication #93952
Title: RIBONUCLEOPROTEIN PARTICLES RELATED TO TRANSLATION ARE STORED IN QUIESCENT MAIZE EMBRYONIC AXES

Author
item RINCON-GUZMAN, ALMA - NACIONAL AUTONOMA MEXICO
item BELTRAN-PENA, ELDA - NACIONAL AUTONOMA MEXICO
item Ortiz Lopez, Adriana
item SANCHEZ, ESTELA - NACIONAL AUTONOMA MEXICO

Submitted to: Plant Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: During seed development, information is transferred from the maternal parent to the seed that is vital for the early events in seed germination. This information is transferred from genes in the parent plant and stored in the dried seed in the form of messenger RNA, the biological blueprint for the construction of proteins. Since messenger RNA usually has a rather short lifetime, a few minutes to a few days, there is a great deal of importance in discovering how messenger RNA in dried seeds can be stabilized for months or even years. This work examines the role of a family of unique proteins that are known to bind messenger RNA in protecting RNA in seeds from degradation. In this work, we isolated these unique proteins which, once bound to messenger RNA, are called ribonuleotide particles, and showed that they play a central role in prolonging the lifetime of RNA during seed development and dry down. These findings are important to a wide range of agricultural scientists interested in the control of seed germination under stresses such as flooded or cold soils.

Technical Abstract: RNA molecules are known to be sequestered and stored as ribonucleoprotein particles (RNPs) in many different tissues, particularly at stages of metabolic quiescency. In this study, RNPs were isolated and characterized from embryonic axes of mature maize seeds. These particles were resolved by sucrose and CsC1 gradient centrifugation and characterized in terms of their RNA and protein contents. Two types of RNP particles of non-ribosomal nature were identified by Northern and Western-blot analysis. The 7S RNP and the SRP (signal recognition particle), both of which are reported for the first time in embryonic axes of mature seeds. The 7S RNP particle was found in large amounts in the embryonic axes of quiescent seeds but as germination progressed the content decreased in the cytoplasm of these tissues while a slight accumulation was observed in the nuclei. This observation correlates with the well-known knowledge that this particle facilitate the export of 55rRNA from the nucleus into the cytoplasm of Xenopus oocytes where it is stored and subsequently used in ribosome assembly after TFIIIA factor is released by competition with L5 ribosomal protein. In regard to the SRP particle, its presence in quiescent axes where the ER is not yet structured suggests that this particle might be required for holding translocation of the target proteins until full membrane organization is reestablished after water imbibition.