Water strategy of mycorrhizal rice at low temperature through the regulation of PIP aquaporins with the involvement of trehalose

Arbuscular mycorrhizal fungi (AMF) are known to improve plants stress tolerance by increasing water absorption and trehalose accumulation. However, the relationship between trehalose and AMF water transport and their role in the mycorrhizal rice water strategy at low temperature has not been established. Different temperature and exogenous trehalose treatment experiments were performed on potted non-mycorrhizal and mycorrhizal rice. The results showed that AMF enhanced rice root water uptake at both normal and low temperatures. At low temperature, the AMF aquaporin (GintAQPF) expression levels were increased and higher rice aquaporin (OsPIPs) expression levels were exhibited in mcyorrhizal rice than non-mycorrhizal rice. The increased trehalose biosynthesis gene transcripts, such as OsTPS1, OsTPS2 and OsTPP1 in mycorrhizal rice roots generated more trehalose than in non-mycorrhizal rice at either normal or low temperature. Application of exogenous trehalose demonstrated that trehalose could regulate AMF and rice water absorption by inducing the expression of GintAQPF and several OsPIPs and create better plant growth conditions. Consequently, we hypothesized that one of the mechanisms by which AMF improve plant resistance to low temperature was AMF-enhanced trehalose accumulation, which could induce AMF and host plants aquaporin expression that then maintain better water relations in mycorrhizal plants at low temperatures. (C) 2014 Elsevier B.V. All rights reserved.