Poster abstracts

Poster number 51 submitted by Liuyin Ma

The role of polyadenylation in seed germination

Liuyin Ma (Depts. of Plant and Soil Sciences, University of Kentucky), Allan Bruce Downie (Depts. of Horticulture,University of Kentucky), Arthur G. Hunt (Depts. of Plant and Soil Sciences, University of Kentucky)

Abstract:
Many groups have reported that seeds contain a sizeable and diverse population of stored mRNAs, and that this pool of stored mRNAs can be the “source” of de novo protein production before the onset of transcription early in germination since 1970s(1,2,3). Most importantly, Harris and Dure(2) suggested that some proportion of the stored mRNA present in cotton seed was polyadenylated shortly after the initiation of germination. In addition, it has been reported that germination is insensitive to more general inhibitors of RNA polymerase II but sensitive to poly (A) polymerase inhibitors(4,5). All of these provide a possible suggestion that unadenylated stored RNA may have function in seed germination upon reactivating by cytoplasmic polyadenylation.

To test this hypothesis, we focused on providing evidence to prove the following hypothesis: 1) unadenylated RNA exists in seed. 2) a cytoplasmic polyadenylation machinery exists in plant. 3) unadenylated stored RNA becomes adenylated RNA during seed germination. Using microarray experiments and Illumina sequencing, we have identified mRNAs that are under- or unadenylated; these results support the first hypothesis. Using a bioinformatic approqach, a number of Arabidopsis orthologs of proteins involved in cytoplasmic polyadenylation in animals have been identified. T-DNA insertion mutants affected in several of these are currently being studied; progress in this characterization will be presented. Finally, an experimental system to study the adenylation of stored RNAs during germination is being developed.

References:
1.Ajtkhozhin, M. A., K. J. Doschanov, and A. U. Akhanov. 1976. Informosomes as a storedform of mRNA in wheat embryos. FEBS Lett 66:124-6.
2.Harris, B., and L. Dure, 3rd. 1978. Developmental regulation in cotton seed germination:polyadenylation of stored messenger RNA. Biochemistry 17:3250-6.
3. Ishibashi, N., D. Yamauchi, and T. Minamikawa. 1990. Stored mRNA in cotyledons of Vigna unguiculata seeds: nucleotide sequence of cloned cDNA for a stored mRNA and induction of its synthesis by precocious germination. Plant Mol Biol 15:59-64.
4.Tao, K. L., and A. A. Khan. 1976. Differential Effects of Actinomycin D and Cordycepin in Lettuce Seed Germination and RNA Synthesis. Plant Physiol 58:769-772.
5.Datta, K., L. Marsh, and A. Marcus. 1983. Early Growth of Wheat Embryonic Axes and the Synthesis of RNA and DNA. Plant Physiol 72:394-397.

Keywords: polyadenylation, seed, germination