Natural Variability of root hydraulic in Arabidopsis grown in normal and salt stress conditions

MOIRA SUTKA, GUOWEI LI, JULIE BOUDET, YANN BOURSIAC, PATRICK DOUMAS, CHRISTOPHE MAUREL

La Plata, Buenos Aires

Congreso; XXVIII Reunion Argentina de Fisiología Vegetal; 2010

SAFV

With the aim to gain insights into the natural variability of root hydraulics and of its molecular components, genotypic differences related to root water transport and plasma membrane aquaporin (PIP) expression were investigated in a series of 13 natural accessions of Arabidopsis thaliana. The hydraulic conductivity of excised root systems (Lpr) showed a 2-fold variation among accessions. The contribution of aquaporins to water uptake was characterized using different inhibitors (mercury, propionic acid, azide). Our data indicate a large variety of hydraulic profiles, with variations in the absolute contribution of the aquaporin-dependent and -independent paths to Lpr. The distinct suberization patterns observed among accessions were not correlated to their root hydraulic profiles. Real-time reverse transcriptase PCR did not reveal any significant positive correlation between Lpr and single PIP transcript abundance. Studies on a subset of 5 accessions (Blh-1, Col-0, Ct-1, Di-M, Mr-0) also revealed quantitative and qualitative differences in root hydraulic responses to salt stress. Thus, Lpr was down regulated in all investigated accessions except Mr-0 where it was up regulated. In this and the Ct-1 accession, root cortical cell hydraulic conductivity was unresponsive to salt whereas it was down regulated in the three other accessions. By contrast, the 5 accessions showed qualitatively similar aquaporin transcriptional profiles in response to salt. The overall work provides clues on how hydraulic regulations allow plant adaptation to a salt stress. It also shows that the wide range of natural variation in root hydraulics previously reported in various species can be observed in the model species Arabidopsis.