Circadian Oscillation And Development-Dependent Expression Of Glycine Rich RNA Binding Proteins In Tomato Fruits

MÜLLER, GABRIELA LETICIA; TRIASSI, AGUSTINA; ALVAREZ, CLARISA ESTER; FALCONE, MARÍA LORENA; ANDREO, CARLOS SANTIAGO; LARA, MARÍA VALERIA; DRINCOVICH, MARÍA FABIANA

FUNCTIONAL PLANT BIOLOGY

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2014 vol. 41 p. 411 - 423

1445-4408

Glycine-rich RNA-binding proteins (GRPs) are involved in RNA metabolism, modulating the posttranscriptional processing of transcripts; and have been suggested as an output signal of the circadian clock. However, neither GRPs nor the circadian rhythmic have been studied in detail in fleshy fruits yet. In the present work, grp1 gene family was analyzed in Micro-Tom tomato fruit. Three highly homologous Legrp1 genes (Legrp1a-c) were identified. For each gene, three transcriptional products were found, which correspond to the un-spliced pre-RNA, the mature mRNA and the alternatively spliced mRNA (preLegrp1a-c, mLegrp1a-c and asLegrp1a-c, respectively). LeGRPs show the classical N-terminal end RNA recognition motif and the C-terminal end glycine-rich region and were found in the nucleus and in the cytosol of tomato fruit. All LeGRP1s complemented the cold-sensitive phenotype of Escherichia coli mutant BX04 cells under cold stress, and harbored in vivo RNA-melting abilities. The levels of all transcriptional forms of Legrp1a-c and the total immunoreactive LeGRP1 decrease during tomato fruit development. Here is shown for the first time particular circadian profiles of expression for each transcriptional Legrp1 form, which are fruit developmental stage dependent, with the green stages independent of plant signals.  During ripening off the vine of fruits harvested at the mature green stage, the levels of all transcriptional forms of Legrp1a-c drastically increased; however, incubation at 4ºC prevented such increases. Correlation analysis of the expression of all Legrp1a-c transcriptional forms suggests a positive regulation of expression in tomato fruit. Overall, the results obtained in this work reveal a complex pattern of expression of GRPs in tomato fruit suggesting they might be involved in posttranscriptional modulation of circadian processes of this fleshy fruit.