Nitrogen regulatory networks in the control of flowering time.

GRAS DE; GUTIÉRREZ RA

Pacifico Yokohama

Conferencia; 21st International Conference on Arabidopsis Research; 2010

RIKEN Plant Science Center

Nitrogen (N) availability is one of the most limiting factors for plant growth and agricultural productivity. Plant growth and developmental aspects such as root architecture, leaf development, seed dormancy and flowering time can be dramatically affected by N supplied to plants. To investigate how plants sense and respond to N at the molecular level to coordinate flowering time, we integrated known floral gene networks with N-networks obtained from publicly databases. Our bioinformatics approach identified important floral genes regulated by N. Among them, several repressors of flowering time belonging to the AP2-type transcription factors are regulated by nitrate including, two TARGET OF EAT 1and 2 (TOE1 and TOE2 respectively), SCHLAFMUTZE (SMZ) and SCHNARCHZAPFEN (SNZ). These genes are targets of microRNA172 (miR172), a regulatory factor that controls flowering time by the photoperiod pathway. To analyze the possible role of these transcription factors in the N-response, we first evaluated the effect of nitrate treatments on the expression of these genes. TOE1,TOE2, SMZ and SNZ mRNA accumulated quickly after KNO3 treatments but not after KCl treatments (as control) indicating they are nitrate responsive genes. We also found that miR172 was down regulated by nitrate treatment. Interestingly, analysis of toe1 toe2 smz snz quadruple mutant does not exhibit late flowering in N-response as observed in wild-type plants. These results prompt a model for nitrate control of flowering time that involves miR172 and their targets, the repressors of flowering time.