Browsing by Author "Willigen, Clare Vander"

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    Anomalous pressure volume curves of resurrection plants do not suggest negative turgor.
    (Oxford University Press, 2001) Willigen, Clare Vander; Farrant, Jill; Pammenter, N W
    Pressure-volume (PV) curves of the desiccation-tolerant angiosperms, Eragrostis nindensis, Craterostigma wilmsii and Xerophyta humilis, and the desiccation-sensitive species, E. curvula, were compared. The shape of curves for E. nindensis and C. wilmsii differed from the usual curvilinear form. Over the relative water content (RWC) range of approx. 70 to 25%, PV curves indicated water potentials higher than directly measured water activity on frozen-thawed tissue. Anatomical studies showed considerable cell wall folding and a consequent reduction in cell volume in these two species; this was not seen in X. humilis or E. curvula which showed normal PV curves. It is suggested that this wall folding may have prevented the development of negative turgor and physical stress in the cells, and contributed to desiccation tolerance. Copyright 2001 Annals of Botany Company.
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    Comparisons of the resurrection grass, Eragrostis nindensis, with the related desiccation-sensitive species, E. curvula
    (2001) Willigen, Clare Vander
    Desiccation tolerance of the inner leaves of Eragrostis nindensis is compared with the desiccation sensitivity of the outer leaves, as well as those of the closely related species, E. curvula. Both E. nindensis and E. curvula dehydrate to a relative water content (RWC) ofless than 5% in two weeks. Photosynthetic activity in E. curvula is maintained down to 40% RWC, after which further drying results in a sudden irreversible breakdown of the photosynthetic system and its pigments.