Phosphate deficiency in plants: the role of extracellular and intracellular ribonucleases

ESCOBAR, ELIANA GISELLE; ARIEL GOLDRAIJ

Córdoba

Congreso; LII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2016

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Phosphate deficiency inplants: the role of extracellular and intracellular ribonucleases Eliana Escobarand Ariel GoldraijDpto. QuímicaBiológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba. CIQUIBIC-CONICETPhosphorus deficiency is a widespread problem in agriculturalareas. Most soils contain significant amounts of P; however, less than 1% of itis available for plant root uptake because inorganic phosphate (Pi), the onlyform in which plants can assimilate P, is rapidly immobilized in soils. Plantsgrowing under Pi limitation trigger a complex set of responses, among which is theinduction of ribonucleases (RNases) to scavenge Pi from ARN. In Nicotiana alata, intracellular NnSR1 (Nicotiana non S-RNase1)and extracellular RNase NE are, thus far, the only RNases known to be inducedunder Pi starvation. To discern the Pi threshold triggering such induction,plants were cultivated under different Pi concentrations. The induction ofRNase NE at 10 µM Pi, assayed by RT-PCR and western blot, suggests that theextracellular RNA may be the first source of P used by the cell under Pistress. To understand the functional role of NnSR1 and RNase NE, a posttranscriptional silencing strategy was developed. The hypervariable sequence ofeach RNase was inserted in opposite directions into an RNAi binary vector. Theseconstructs were introduced into Nicotianaleaf disks via Agrobacteriuminfection. The level of RNase NE, which is constitutively expressed in floralorgans, was assayed on regenerated plants. The analysis of silenced plants growingunder conditions of Pi deficiency is discussed.