title: Root ABA Accumulation Enhances Rice Seedling Drought Tolerance under Ammonium Supply: Interaction with Aquaporins.
abstract: In previous studies, we demonstrated that ammonium nutrition enhances the drought tolerance of rice seedlings compared to nitrate nutrition and contributes to a higher root water uptake ability. It remains unclear why rice seedlings maintain a higher water uptake ability when supplied with ammonium under drought stress. Here, we focused on the effects of nitrogen form and drought stress on root abscisic acid (ABA) concentration and aquaporin expression using hydroponics experiments and stimulating drought stress with 10% PEG6000. Drought stress decreased the leaf photosynthetic rate and stomatal conductivity and increased the leaf temperature of plants supplied with either ammonium or nitrate, but especially under nitrate supply. After 4 h of PEG treatment, the root protoplast water permeability and the expression of root PIP and TIP genes decreased in plants supplied with ammonium or nitrate. After 24 h of PEG treatment, the root hydraulic conductivity, the protoplast water permeability, and the expression of some aquaporin genes increased in plants supplied with ammonium compared to those under non-PEG treatment. Root ABA accumulation was induced by 24 h of PEG treatment, especially in plants supplied with ammonium. The addition of exogenous ABA decreased the expression of PIP and TIP genes under non-PEG treatment but increased the expression of some of them under PEG treatment. We concluded that drought stress induced a down-regulation of aquaporin expression, which appeared earlier than did root ABA accumulation. With continued drought stress, aquaporin expression and activity increased due to root ABA accumulation in plants supplied with ammonium.
authors: Jiangsu Key Lab for Organic Waste Utilization, Nanjing Agricultural UniversityNanjing, China; Institut des Sciences de la Vie, Université catholique de LouvainLouvain-la-Neuve, Belgium.
authors: Lei
authors: L
authors: Ding
authors: Jiangsu Key Lab for Organic Waste Utilization, Nanjing Agricultural University Nanjing, China.
authors: Yingrui
authors: Y
authors: Li
authors: Jiangsu Key Lab for Organic Waste Utilization, Nanjing Agricultural University Nanjing, China.
authors: Ying
authors: Y
authors: Wang
authors: Jiangsu Key Lab for Organic Waste Utilization, Nanjing Agricultural University Nanjing, China.
authors: Limin
authors: L
authors: Gao
authors: Jiangsu Key Lab for Organic Waste Utilization, Nanjing Agricultural University Nanjing, China.
authors: Min
authors: M
authors: Wang
authors: Institut des Sciences de la Vie, Université catholique de Louvain Louvain-la-Neuve, Belgium.
authors: François
authors: F
authors: Chaumont
authors: Jiangsu Key Lab for Organic Waste Utilization, Nanjing Agricultural University Nanjing, China.
authors: Qirong
authors: Q
authors: Shen
authors: Jiangsu Key Lab for Organic Waste Utilization, Nanjing Agricultural University Nanjing, China.
authors: Shiwei
authors: S
authors: Guo
keywords: ABA; aquaporin; drought stress; rice; water uptake