The ATP in roots and xylem sap of two woody plant species, Platycladus orientalis and Acacia auriculiformis, subjected to rapid and slow soil drying has been determined employing firefly luciferase ATP assay method (s...The ATP in roots and xylem sap of two woody plant species, Platycladus orientalis and Acacia auriculiformis, subjected to rapid and slow soil drying has been determined employing firefly luciferase ATP assay method (sensitivity is at 10<sup>-12</sup> mol ATP L<sup>-1</sup>). The ATP levels in the two species were 1.6 nmol. g<sub>DW</sub><sup>-1</sup> and 0.6 nmol. g<sub>DW</sub><sup>-1</sup> in roots, and 5.6 μmol·m<sup>-3</sup> and 8 μmol ·m<sup>-3</sup> in xylem sap, respectively. When plants of P. orientalis and A. auriculiformis were subjected to rapid soil drying, respectively, as soil water content （SWC） decreased from the normal level ( 0.2.5 g·g<sub>DW</sub><sup>-1</sup>) to 0.02 and 0.06 g·g<sub>DW</sub><sup>-1</sup>, separately, plant water potential （ ψ ）dropped to - 4 and - 3.2 MPa, differently, the ATP in roots decreased 99.7% and 42%, respectively. When the rapidly dried soil was watered for up to 6 d, SWC and ψ, were found to recover to their normal levels, but ATP content in roots of P. orientalis and A. auriculiformis recovered by 10% and 23%, respectively. When plants展开更多
Soybean genotypes show diverse physiological responses to drought, but specific physiological traits that can be used to evaluate drought tolerance have not been identified. In the present study we investigated physio...Soybean genotypes show diverse physiological responses to drought, but specific physiological traits that can be used to evaluate drought tolerance have not been identified. In the present study we investigated physiological traits of soybean genotypes under progressive soil drying and rewetting, using a treatment mimicking field conditions.After a preliminary study with eight soybean genotypes, two drought-tolerant genotypes and one susceptible genotype were grown in the greenhouse and subjected to water restriction. Leaf expansion rate, gas exchange, water relation parameters, total chlorophyll(Chl), proline contents of leaves, and root xylem p H were monitored in a time course, and plant growth and root traits were measured at the end of the stress cycle. Drought-tolerant genotypes maintained higher leaf expansion rate, net photosynthetic rate(Pn), Chl content,instantaneous water use efficiency(WUEi), % relative water content(RWC), water potential(ψw), and turgor potential(ψp) during progressive soil drying and subsequent rewetting than the susceptible genotypes. By contrast, stomatal conductance(gs) and transpiration rate(Tr)of tolerant genotypes declined faster owing to dehydration and recovered more sharply after rehydration than the same parameters in susceptible ones. Water stress caused a significant increase in leaf proline level and root xylem sap p H of both genotypes but tolerant genotypes recovered to pre-stress levels more quickly after rehydration. Tolerant genotypes also produced longer roots with higher dry mass than susceptible genotypes. We conclude that rapid perception and adjustment in response to soil drying and rewetting as well as the maintenance of relatively high Pn, %RWC, and root growth constitute the mechanisms by which drought-tolerant soybean genotypes cope with water stress.展开更多
Two woody plants, Platycladus orientalise (tolerant to drought) and Acacia auriculi-formis (sensitive to drought), have been subjected to rapid and slow soil drying. ABA levels in their roots and xylem sap have been d...Two woody plants, Platycladus orientalise (tolerant to drought) and Acacia auriculi-formis (sensitive to drought), have been subjected to rapid and slow soil drying. ABA levels in their roots and xylem sap have been determined using radioimmunoassay (RIA, sensitivity is 0.4 pmol per assay vial) with a monoclonal antibody against ( + )-ABA. ABA contents of P. orientalise and A. auriculiformis growing in well watered soil are 0.3 and 2.5 nmol-gDW-1 in展开更多
文摘The ATP in roots and xylem sap of two woody plant species, Platycladus orientalis and Acacia auriculiformis, subjected to rapid and slow soil drying has been determined employing firefly luciferase ATP assay method (sensitivity is at 10<sup>-12</sup> mol ATP L<sup>-1</sup>). The ATP levels in the two species were 1.6 nmol. g<sub>DW</sub><sup>-1</sup> and 0.6 nmol. g<sub>DW</sub><sup>-1</sup> in roots, and 5.6 μmol·m<sup>-3</sup> and 8 μmol ·m<sup>-3</sup> in xylem sap, respectively. When plants of P. orientalis and A. auriculiformis were subjected to rapid soil drying, respectively, as soil water content （SWC） decreased from the normal level ( 0.2.5 g·g<sub>DW</sub><sup>-1</sup>) to 0.02 and 0.06 g·g<sub>DW</sub><sup>-1</sup>, separately, plant water potential （ ψ ）dropped to - 4 and - 3.2 MPa, differently, the ATP in roots decreased 99.7% and 42%, respectively. When the rapidly dried soil was watered for up to 6 d, SWC and ψ, were found to recover to their normal levels, but ATP content in roots of P. orientalis and A. auriculiformis recovered by 10% and 23%, respectively. When plants
基金supported by the Hong Kong RGC Collaborative Research Fund (CUHK3/CRF/ 11G) to Prof. H.-M. Lam. and J.H. Zhang
文摘Soybean genotypes show diverse physiological responses to drought, but specific physiological traits that can be used to evaluate drought tolerance have not been identified. In the present study we investigated physiological traits of soybean genotypes under progressive soil drying and rewetting, using a treatment mimicking field conditions.After a preliminary study with eight soybean genotypes, two drought-tolerant genotypes and one susceptible genotype were grown in the greenhouse and subjected to water restriction. Leaf expansion rate, gas exchange, water relation parameters, total chlorophyll(Chl), proline contents of leaves, and root xylem p H were monitored in a time course, and plant growth and root traits were measured at the end of the stress cycle. Drought-tolerant genotypes maintained higher leaf expansion rate, net photosynthetic rate(Pn), Chl content,instantaneous water use efficiency(WUEi), % relative water content(RWC), water potential(ψw), and turgor potential(ψp) during progressive soil drying and subsequent rewetting than the susceptible genotypes. By contrast, stomatal conductance(gs) and transpiration rate(Tr)of tolerant genotypes declined faster owing to dehydration and recovered more sharply after rehydration than the same parameters in susceptible ones. Water stress caused a significant increase in leaf proline level and root xylem sap p H of both genotypes but tolerant genotypes recovered to pre-stress levels more quickly after rehydration. Tolerant genotypes also produced longer roots with higher dry mass than susceptible genotypes. We conclude that rapid perception and adjustment in response to soil drying and rewetting as well as the maintenance of relatively high Pn, %RWC, and root growth constitute the mechanisms by which drought-tolerant soybean genotypes cope with water stress.
文摘Two woody plants, Platycladus orientalise (tolerant to drought) and Acacia auriculi-formis (sensitive to drought), have been subjected to rapid and slow soil drying. ABA levels in their roots and xylem sap have been determined using radioimmunoassay (RIA, sensitivity is 0.4 pmol per assay vial) with a monoclonal antibody against ( + )-ABA. ABA contents of P. orientalise and A. auriculiformis growing in well watered soil are 0.3 and 2.5 nmol-gDW-1 in
