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. 1. Evidence from pressure-volume curve analysis of dead tissue.
abstract: This paper provides a mini-review of evidence for negative turgor pressure in leaf cells starting with experimental evidence in the late 1950s and ending with biomechanical models published in 2014. In the present study, biomechanical models were used to predict how negative turgor pressure might be manifested in dead tissue, and experiments were conducted to test the predictions. The main findings were as follows: (i) Tissues killed by heating to 60 or 80 °C or by freezing in liquid nitrogen all became equally leaky to cell sap solutes and all seemed to pass freely through the cell walls. (ii) Once cell sap solutes could freely pass the cell walls, the shape of pressure-volume curves was dramatically altered between living and dead cells. (iii) Pressure-volume curves of dead tissue seem to measure negative turgor defined as negative when inside minus outside pressure is negative. (iv) Robinia pseudoacacia leaves with small palisade cells had more negative turgor than Metasequoia glyptostroboides with large cells. (v) The absolute difference in negative turgor between R. pseudoacacia and M. glyptostroboides approached as much as 1.0 MPa in some cases. The differences in the manifestation of negative turgor in living versus dead tissue are discussed.
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: Shaoan
authors.initials: S
authors.lastname: Pan
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: D048430:Cell Shape; D048429:Cell Size; D029779:Cupressaceae / Q000166:cytology / Q000502:physiology*; D009995:Osmosis; D059828:Plant Cells / Q000378:metabolism*; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000166:cytology / Q000502:physiology*; D011312:Pressure; D031301:Robinia / Q000166:cytology / Q000502:physiology*; D013045:Species Specificity
keywords: Höfler diagram; apoplastic water; bulk modulus of elasticity; leaf water relations; micromechanical models; negative turgor; osmotic pressure; pressure-volume curves; thermocouple psychrometer