Plants maintain water balance by varying hydraulic properties, and plasma membrane intrinsic proteins（PIPs） may be involved in this process. Leaf xylem and root hydraulic conductivity and the m RNA contents of four ...Plants maintain water balance by varying hydraulic properties, and plasma membrane intrinsic proteins（PIPs） may be involved in this process. Leaf xylem and root hydraulic conductivity and the m RNA contents of four highly expressed Zm PIP genes（Zm PIP1;1, Zm PIP1;2, Zm PIP2;2, and Zm PIP2;5） in maize（Zea mays） seedlings were investigated. Under well-watered conditions, leaf hydraulic conductivity（K_（leaf）） varied diurnally and was correlated with whole-plant hydraulic conductivity. Similar diurnal rhythms of leaf transpiration rate（E）, K_（leaf） and root hydraulic conductivity（K_（root）） in well-watered plants are important for maintaining whole-plant water balance. After 2 h of osmotic stress treatment induced by 10% polyethylene glycol 6000, the K_（root） of stressed plants decreased but K_（leaf） increased, compared with well-watered plants. The m RNA contents of four Zm PIPs were significantly up-regulated in the leaves of stressed plants, especially for Zm PIP1;2. Meanwhile, Zm PIP2;5 was significantly down-regulated in the roots of stressed plants. After 4 h of osmotic stress treatment, the E and leaf xylem water potentials of stressed plants unexpectedly increased. The increase in K_（leaf） and a partial recovery of K_（root） may have contributed to this process. The m RNA content of Zm PIP1;2 but not of the other three genes was up-regulated in roots at this time. In summary, the m RNA contents of these four Zm PIPs associated with K_（leaf） and K_（root） change in maize seedlings during short-term osmotic stress, especially for Zm PIP1;2 and Zm PIP2;5, which may help to further reveal the hydraulic resistance adjustment role of Zm PIPs.展开更多
Water uptake is crucial for crop growth and development and drought stress tolerance. The water channel aquaporins(AQP) play important roles in plant water uptake. Here, we discovered that a jasmonic acid analog, coro...Water uptake is crucial for crop growth and development and drought stress tolerance. The water channel aquaporins(AQP) play important roles in plant water uptake. Here, we discovered that a jasmonic acid analog, coronatine(COR), enhanced maize(Zea mays) root water uptake capacity under artificial water deficiency conditions. COR treatment induced the expression of the AQP gene Plasma membrane intrinsic protein 2;5(ZmPIP2;5).In vivo and in vitro experiments indicated that COR also directly acts on ZmPIP2;5 to improve water uptake in maize and Xenopus oocytes. The leaf water potential and hydraulic conductivity of roots growing under hyperosmotic conditions were higher in ZmPIP2;5-overexpression lines and lower in the zmpip2;5 knockout mutant, compared to wild-type plants. Based on a comparison between ZmPIP2;5 and other PIP2s, we predicted that COR may bind to the functional site in loop E of ZmPIP2;5. We confirmed this prediction by surface plasmon resonance technology and a microscale thermophoresis assay, and showed that deleting the binding motif greatly reduced COR binding. We identified the N241 residue as the COR-specific binding site, which may activate the channel of the AQP tetramer and increase water transport activity,which may facilitate water uptake under hyperosmotic stress.展开更多
基金financially supported by the National Natural Science Foundation of China (31400527, 31501276)the National High-Tech R&D Program of China (2011AA100504)+1 种基金the Project 111 of the Ministry of Education of China (B12007)the Fund of State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, China (K318009902-1408)
文摘Plants maintain water balance by varying hydraulic properties, and plasma membrane intrinsic proteins（PIPs） may be involved in this process. Leaf xylem and root hydraulic conductivity and the m RNA contents of four highly expressed Zm PIP genes（Zm PIP1;1, Zm PIP1;2, Zm PIP2;2, and Zm PIP2;5） in maize（Zea mays） seedlings were investigated. Under well-watered conditions, leaf hydraulic conductivity（K_（leaf）） varied diurnally and was correlated with whole-plant hydraulic conductivity. Similar diurnal rhythms of leaf transpiration rate（E）, K_（leaf） and root hydraulic conductivity（K_（root）） in well-watered plants are important for maintaining whole-plant water balance. After 2 h of osmotic stress treatment induced by 10% polyethylene glycol 6000, the K_（root） of stressed plants decreased but K_（leaf） increased, compared with well-watered plants. The m RNA contents of four Zm PIPs were significantly up-regulated in the leaves of stressed plants, especially for Zm PIP1;2. Meanwhile, Zm PIP2;5 was significantly down-regulated in the roots of stressed plants. After 4 h of osmotic stress treatment, the E and leaf xylem water potentials of stressed plants unexpectedly increased. The increase in K_（leaf） and a partial recovery of K_（root） may have contributed to this process. The m RNA content of Zm PIP1;2 but not of the other three genes was up-regulated in roots at this time. In summary, the m RNA contents of these four Zm PIPs associated with K_（leaf） and K_（root） change in maize seedlings during short-term osmotic stress, especially for Zm PIP1;2 and Zm PIP2;5, which may help to further reveal the hydraulic resistance adjustment role of Zm PIPs.
基金supported by the National Key Research and Development Program of China (2016YFD0300102-4)。
文摘Water uptake is crucial for crop growth and development and drought stress tolerance. The water channel aquaporins(AQP) play important roles in plant water uptake. Here, we discovered that a jasmonic acid analog, coronatine(COR), enhanced maize(Zea mays) root water uptake capacity under artificial water deficiency conditions. COR treatment induced the expression of the AQP gene Plasma membrane intrinsic protein 2;5(ZmPIP2;5).In vivo and in vitro experiments indicated that COR also directly acts on ZmPIP2;5 to improve water uptake in maize and Xenopus oocytes. The leaf water potential and hydraulic conductivity of roots growing under hyperosmotic conditions were higher in ZmPIP2;5-overexpression lines and lower in the zmpip2;5 knockout mutant, compared to wild-type plants. Based on a comparison between ZmPIP2;5 and other PIP2s, we predicted that COR may bind to the functional site in loop E of ZmPIP2;5. We confirmed this prediction by surface plasmon resonance technology and a microscale thermophoresis assay, and showed that deleting the binding motif greatly reduced COR binding. We identified the N241 residue as the COR-specific binding site, which may activate the channel of the AQP tetramer and increase water transport activity,which may facilitate water uptake under hyperosmotic stress.
