Relationship of root aquaporin genes, ospip1;3, ospip2;4, ospip2;5, ostip2;1 and osnip2;1 expression with drought tolerance in rice

Abstract

Aquaporins are channel proteins that facilitate the passive uptake and transport of water, ions, molecules and regulate the water balance at the plant level. Genes for aquaporins are important since they play a major role in water uptake. The present study was therefore conducted to assess the relationship of aquaporins predominantly expressed in roots in response to drought tolerance. Transcript abundance of five rice aquaporin genes (PIP2;5, PIP1;3, PIP2;4, TIP2;1 and NIP2;1) in five rice genotypes (Banglami, ARC 10372, Inglongkiri, Ranjit and IR 64) under well-watered and drought stress conditions were measured using qRTPCR. Significant variation in PIP relative transcript abundance in roots was observed between varieties under both well-watered and drought stress conditions. In roots, the expression levels of most OsPIPs were found to be increased in drought stress conditions. OsPIP1;3, OsPIP2;5, OsTIP2;1 and OsNIP2;1 were upregulated more in upland (drought tolerant) rice and Ranjit lowland (moderately drought tolerant) genotypes than drought susceptible lowland IR-64 rice in drought stress conditions and downregulated/unchanged in well-irrigated conditions. The OsPIP genes were identified as candidate genes based on their high expression under drought stress situations and played a significant role in water uptake and root development under water stress conditions. A positive correlation was observed between fold increase in aquaporin expression and degree of drought tolerance which suggest that these aquaporins genes might play an important role in root development under water stress situation to overcome stress.