XVI International Botanical Congess

Selective mRNA translation occurs in the root tips of flooded maize seedlings. This regulation occurs concomitantly with an increase in cytosolic calcium and decrease in cytosolic pH. Our studies focus on the translational machinery that is involved in the recruitment of mRNA to ribosomes. Many of these are modified in response to anoxia, including: eIF4E, the cap-binding protein of the eIF4F cap-binding complex, eIF4A, and RNA-helicase that assists eIF4F and eIFiso4F in removal of mRNA structure during ribosome recruitment, ribosomal protein S6, involved in selective translation of a subset of cellular mRNAs in mammals, and the acidic stalk structure of the large ribosomal subunit, involved in selective mRNA translation in yeast. The treatment of aerobic seedlings with caffeine increases cytosolic calcium and promotes a number of the post-translational modifications that are observed in response to anoxia. These modifications are inhibited under anoxia if ruthenium red is present, an intracellular calcium channel blocker. The dynamic spatial-temporal modulation of cytosolic calcium and pH may regulate protein synthesis.