Barley amino acid transporters gene expression along leaf life-time is modulated by S starvation

CINTIA G. VELIZ; IRMA N. ROBERTS; CARLA PAULA CAPUTO SUAREZ

Foz de Iguazu

Congreso; 11th International Congrees of Plant Molecular Biology; 2015

In cereals a great proportion of the nitrogen (N) required for the developing grains is guaranteed by amino acids remobilization, a process depending on amino acid transporters (AATs) proteins. Over the past decade, sulphur (S) availability has been decreasing in several areas affecting both crops yield and grain storage proteins profile. Information about regulation of AATs expression is scarce and to date there are no reports on how this expression is affected by S deficiency. Here, we analyzed the expression pattern of six barley AATs genes as affected by natural senescence and by S starvation. Barley plants were supplied with 1.2 mM S-SO till leaf n°3 emerged and then, two treatments were established: control plants, maintained in the same growing conditions, and S-starved plants, supplied with 1.25 µM S-SO. Samples of leaf nº3 were collected at 0, 3, 7, and 14 days after full expansion for qRT-PCR analysis. In control plants, the expression levels of HvAAP2 and HvAAP4 decreased, HvAAP7 and HvProT1 increased and HvAAP6 and HvLHT2 kept constant along time. On the other hand, S starvation generated a diminution in the expression of HvAAP4, HvAAP6, HvAAP7 and HvProT1 but did not affect HvAAP2 and HvLHT2 gene expression compared to control plants. Our results suggest differential roles of these AATs during the life-time of the leaf under natural senescence and demonstrate down-regulation of its gene expression under S starvation, highlighting the impact of limiting S availability on N compounds remobilization during plant senescence