title: Experimental evidence for negative turgor pressure in small leaf cells of Robinia pseudoacacia L versus large cells of Metasequoia glyptostroboides Hu et W.C. Cheng. 2. Höfler diagrams below the volume of zero turgor and the theoretical implication for pressure-volume curves of living cells.
abstract: The physiological advantages of negative turgor pressure, Pt, in leaf cells are water saving and homeostasis of reactants. This paper advances methods for detecting the occurrence of negative Ptin leaves. Biomechanical models of pressure-volume (PV) curves predict that negative Ptdoes not change the linearity of PV curve plots of inverse balance pressure, PB, versus relative water loss, but it does predict changes in either the y-intercept or the x-intercept of the plots depending on where cell collapse occurs in the PBdomain because of negative Pt. PV curve analysis of Robinia leaves revealed a shift in the x-intercept (x-axis is relative water loss) of PV curves, caused by negative Ptof palisade cells. The low x-intercept of the PV curve was explained by the non-collapse of palisade cells in Robinia in the PBdomain. Non-collapse means that Ptsmoothly falls from positive to negative values with decreasing cell volume without a dramatic change in slope. The magnitude of negative turgor in non-collapsing living cells was as low as -1.3 MPa and the relative volume of the non-collapsing cell equaled 58% of the total leaf cell volume. This study adds to the growing evidence for negative Pt.
authors.affiliation: College of Forestry, Northwest A&F University, Yangling, Shaanxi, 712100, China.|College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, China.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Yang
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, China.
authors.forename: Junhui
authors.initials: J
authors.lastname: Li
authors.affiliation: Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences, Beijing, 100094, China.
authors.forename: Yiting
authors.initials: Y
authors.lastname: Ding
authors.affiliation: College of Forestry, Northwest A&F University, Yangling, Shaanxi, 712100, China.|Center for Nano- and Micro-Mechanics, Engineering Mechanics, Tsinghua University, Beijing, 100084, China.
authors.forename: Melvin T
authors.initials: MT
authors.lastname: Tyree
mesh_terms: D048429:Cell Size; D002473:Cell Wall / Q000378:metabolism; D029779:Cupressaceae / Q000166:cytology / Q000502:physiology*; D058503:Mesophyll Cells / Q000378:metabolism; D008954:Models, Biological; D059828:Plant Cells / Q000378:metabolism*; D019441:Plant Epidermis / Q000502:physiology; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000166:cytology / Q000502:physiology*; D011312:Pressure; D031301:Robinia / Q000166:cytology / Q000502:physiology*; D014867:Water
chemical_list: D014867:Water
keywords: Höfler diagram; apoplastic water; bulk modulus of elasticity; leaf water relations; micromechanical models; negative turgor; osmotic pressure; pressure volume curves; thermocouple psychrometer