Abstract Detail

Bryology and Lichenology

Stark, Lloyd R [1], Greenwood, Joshua L [2], Brinda, John C [3], Slate, Mandy [4].

Suprasaturated Shoots of Syntrichia norvegica are not Constitutively Desiccation Tolerant: Assessing Rate of Drying and Equilibrating Relative Humidity.

Species of Syntrichia and even bryophytes in general have long been considered to exhibit an ecological strategy of constitutive desiccation tolerance (CDT) in vegetative tissues, i.e., capable of surviving any rate of drying to an equilibrating relative humidity (RH) of ~50% with minimal damage to shoots. Shoots of Syntrichia norvegica, a high elevation species, were cloned and cultured under growth chamber conditions to maturity from a single collection in Nevada. Shoots were maintained throughout development in a suprasaturated condition, i.e., in continuous contact with external water among the leaves in order to achieve unequivocal dehardened status with respect to DT. These deacclimated shoots were then blotted to full turgor without external water and subjected to drying at different rates at each of the following equilibrating RHs using saturated salt solutions: 0, 23, 54, and 75%. Variable rates of drying at each equilibrating RH were achieved using different volumes of water on filter papers within lidded, unlidded, parafilmed, or unparafilmed Petri dishes placed inside desiccators. Drying times ranged from 30 min (rapid-dry) to over 200 h (very slow-dry). Response measures included visible leaf damage, regeneration potential, and chlorophyll fluorescence. A complex pattern of recovery is indicated, where leaf damage (especially) and regeneration potential (less so) are mitigated as the rate of drying is extended and water content is increased. Equilibrating RH had a marked effect on shoot health, with much less recovery seen at RHs <50% despite longer drying times. Nevertheless, shoots remained viable across all treatments, indicating at least some vegetative cells are constitutively protected. For the first time, a species of Syntrichia is shown not to incorporate a strategy of constitutive DT, but rather to exhibit a complex strategy of recovery including elements of both inducible and constitutive DT, with the response dependent upon the rate of drying in conjunction with the equilibrating RH.

1 - Department Of Biological Sciences, SCHOOL OF LIFE SCIENCES, UNIVERSITY OF NEVADA, LAS VEGAS, NV, 89154-4004, USA
2 - UNLV, School of Life Sciences, 4505 Maryland Parkway, Las Vegas, Nevada, 89154-4004, United States
3 - Missouri Botanical Garden, Bryology, P.O. Box 299, St. Louis, Missouri, 63166-0299, USA
4 - University Of Montana, OBE, 1701 Stoddard Av, Missoula, MT, 59802, USA

Keywords:
inducible
constitutive
desiccation tolerance
relative humidity
rate of drying
shoots
clonal cultures.

Presentation Type: Oral Paper
Session: 8, Bryology and Lichenology (ABLS) I
Location: 205/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 10:45 AM
Number: 8007
Abstract ID:111
Candidate for Awards:None