Root aquaporins contribute to whole plant water fluxes under drought stress in rice (Oryza sativa L.). (24th November 2015)

• Record Type: Journal Article
• Authors: Grondin, Alexandre; Mauleon, Ramil; Vadez, Vincent; Henry, Amelia
• Is Part Of: Plant, cell and environment. Volume 39:Number 2(2016)
• Page Start: 347
• Page End: 365
• Publication Date: 2015-11-24
• Subjects: aquaporins -- plasma membrane intrinsic proteins -- azide -- root hydraulic conductivity -- sap exudation -- leaf water potential -- transpiration rate; Plant physiology -- Periodicals; Plant cells and tissues -- Periodicals; Plant communities -- Periodicals; 581.105
• DOI: 10.1111/pce.12616
• Languages: English
• ISSNs: 0140-7791

Abstract

Abstract: Aquaporin activity and root anatomy may affect root hydraulic properties under drought stress. To better understand the function of aquaporins in rice root water fluxes under drought, we studied the root hydraulic conductivity ( Lp r) and root sap exudation rate ( S r) in the presence or absence of an aquaporin inhibitor (azide) under well‐watered conditions and following drought stress in six diverse rice varieties. Varieties varied in Lp r and S r under both conditions. The contribution of aquaporins to Lp r was generally high (up to 79% under well‐watered conditions and 85% under drought stress) and differentially regulated under drought. Aquaporin contribution to S r increased in most varieties after drought, suggesting a crucial role for aquaporins in osmotic water fluxes during drought and recovery. Furthermore, root plasma membrane aquaporin (PIP) expression and root anatomical properties were correlated with hydraulic traits. Three chromosome regions highly correlated with hydraulic traits of the OryzaSNP panel were identified, but did not co‐locate with known aquaporins. These results therefore highlight the importance of aquaporins in the rice root radial water pathway, but emphasize the complex range of additional mechanisms related to root water fluxes and drought response. Abstract : Aquaporin activity and root anatomy may affect root hydraulic properties under drought stress. We studied the root hydraulic conductivity, root sap exudation rate and transpiration rate in the presence or absence of an aquaporin inhibitor (azide) under well‐watered conditions and following drought stress in rice. The results suggest that rice root aquaporins can contribute but are not limiting to hydrostatic water fluxes when transpiration is high, but play a major role in osmotic water fluxes occurring when transpiration is low. This paper provides novel insights into rice root hydraulics under drought, aquaporin expression, and related genomic regions. The results have implications for approaches in improving drought tolerance in rice, which is a significant need for rainfed farmers of South and Southeast Asia.