Tissue expression pattern of two aquaporin-encoding genes in different organs of the seagrass Posidonia oceanica

This paper is aimed to perform a detailed expression pattern of two aquaporin-encoding genes, PoPIP;1 and PoTIP;1, previously isolated in Posidonia oceanica. The expression domains of the two genes in different organs and plant tissues were defined by in situ hybridization technique. The results showed clear differences in the expression pattern of the two aquaporin-encoding genes: PoPIP;1 transcript was associated with the meristematic region of the apical meristems (shoot and root), whereas the PoTIP;1 was mainly associated with the tissues showing a well-differentiated vacuole compartment. Moreover, PoPIP;1 intensively marked the epidermal and sub-epidermal cells in the leaves and also in the provascular and vascular tissues. After hypersalinity treatment, the PoTIP;1 tissue expression strongly increased compared to that of PoPIP;1. These in situ results may hypothesize a different involvement of these AQps encoding genes in the water balance and/or solute transport in the different organs and tissues of P. oceanica.