Overexpression of ribonucleases in Nicotiana alata plants exposed to phosphate starvation

ROJAS HJ; GOLDRAIJ A

Puerto Madryn

Congreso; SAIB Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular; 2010

SAIB

     In many plant species the expression of different T2 ribonucleases is induced by phosphate starvation, possibly to scavenge phosphate from RNA. We assayed the induction of S-RNases, a particular type of T2 ribonuclease involved in self-incompatibility. Plants of Nicotiana alata were hydroponically cultivated in Hoagland medium with and without inorganic phosphate (Pi). Plants subjected to Pi starvation showed less growth and exhibited several morphological changes in the root system with respect to controls. Semiquantitative allele-specific RT-PCR showed expression of R6, a novel S-RNase allele of Nicotiana alata, only in roots exposed to Pi deprivation. The induction of R6 is detected after 14 days of Pi depletion in the culture medium. Moreover, the induction was also detected using degenerated oligonucleotides based on S-RNase C2 and C4 conserved domains. This suggests that over expression is not restricted only to R6, but rather that, it would involve other ribonucleases. In gel ribonuclease activity assay showed several bands induced by Pi deprivation, two of which were slightly higher than 31 kDa, a molecular weight close to S-RNase sizes tipically ranging between 30-35 kDa. These results suggest that S-RNase functions are not restricted to the reproductive process only and indicate that they could participate in other biological roles requiring ribonucleases.