Expression of an aquaporin at night in relation to the growth and root water permeability in barley seedlings

Both root and shoot of barley seedlings showed continuous growth at night as well as in the daytime. Root hydraulic conductivity (Lp(r)) was monitored, and high Lp(r) values were recorded at night. For revealing the molecular mechanism, the presence of an aquaporin HvPIP2;1 in barley roots was investigated. The accumulation of the HvPIP2;1 transcript was mostly observed from the evening to the middle of the night. HvPIP2;1 protein was most abundant around midnight. As for tissue localization, HvPIP2;1 protein was abundant in cells involved in water transport. These results suggested the possible involvement of HvPIP2;1 in the mechanism of water transport in roots.