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Characterization and Complexity of Wheat Developing Endosperm mRNAs
1Laboratoire d'Etude des Protéines, Département de Physiologie et Biochimie végétales, Centre I.N.R.A., route de St Cyr, 78000 Versailles, France.
Plant Physiology
|September 1, 1984
Summary
Wheat endosperm studies reveal distinct mRNA populations in free and membrane-bound polysomes. Membrane-bound RNAs encode abundant seed storage proteins, primarily gliadins, while free polysomes contain diverse, mostly rare, sequences.
Area of Science:
- Molecular Biology
- Plant Biochemistry
- Gene Expression
Background:
- Developing wheat endosperm utilizes distinct polysome populations for protein synthesis.
- Polyadenylated RNAs (polyA(+) RNAs) are crucial for translation regulation.
Purpose of the Study:
- To characterize and compare mRNA populations associated with free and membrane-bound (MB) polysomes in wheat endosperm.
- To determine the abundance classes and diversity of mRNAs in these fractions.
Main Methods:
- Isolation of free and MB polysomes and their associated polyA(+) RNAs from developing wheat endosperm (Triticum aestivum L.).
- Analysis of RNA size and poly(A) tail length using sucrose gradient centrifugation and hybridization.
- Synthesis of complementary DNAs (cDNAs) and hybridization kinetics experiments to quantify mRNA abundance classes.
Main Results:
- MB poly(A)(+) RNAs (11S-12S) possess a 7% poly(A) tail and comprise two abundance classes: superabundant (75 species) and intermediate (750 species).
- Free polysomal mRNA is divided into three classes, including superabundant sequences overlapping with MB mRNAs and a large population of rare sequences (~11,000 diverse sequences).
- Some shared mRNAs between free and MB populations suggest potential contamination or polysome trafficking.
Conclusions:
- Wheat endosperm superabundant mRNAs, primarily encoding seed storage proteins like gliadins, are concentrated in MB polysomes.
- Free polysomes contain a greater diversity of mRNAs, predominantly rare sequences, with some overlap with MB populations.
- The findings provide insights into the differential distribution and function of polysomal mRNA populations during wheat seed development.