CONICET | Buscador de Institutos y Recursos Humanos

A balance between water loss by the shoot through transpiration and the capacity for water transport by the root is essential to the coordinated growth and development of plants and also to the plant´s appropriate response to environmental perturbations. Aquaporins have been suggested as dynamic regulators of root hydraulic conductivity to match the transpirational demand of the leaves. To understand the mechanistic aspects of such regulation we are using Arabidopsis thaliana lines which show altered transpiration rates due to genetic manipulation of their stomatal densities, which range from 50% to 200% of the values shown by the wild type line (Col 0) and which result in matching variations in transpiration rates (Dow et al. 2013, New Phytol 201: 1218-1226). We developed a growth protocol for these lines consisting in germination in vertical plates of solid 0.5X MS medium and transfer of two-week old seedlings to hydroponic conditions for a further two-week growth in a temperature controlled chamber, with a photoperiod of 12 hours. The epf1 and epf1 epf2 lines showed plant morphology, rosette areas and growth rates similar to those of the wild type. The mutant epf1 presented a stomatal density 52% higher than that of the wild type and a 47% higher whole-rosette transpiration; while the double mutant epf1 epf2, presented a stomatal density 84% higher than that of the wild type and a similarly high (82%) whole-rosette transpiration rate (all data p < 0.01). Our next step includes characterizing the root hydraulics of the mutant lines with differential stomatal density, with the aim of delineating the aquaporin-dependent and -independent paths of water transport and their modulation by the driving force of transpiration.