Abstract Detail

The impact of climate change on plant physiology in natural and agricultural systems

Holmlund, Helen [1], Fuenzalida, Tomas I. [2], Bryant, Callum [2], Chen, Hua [3], Lee, Jiwon [3], Pittermann, Jarmila [4], Ball, Marilyn [2].

Salt tolerance in mangrove ferns: effects of edaphic and atmospheric water availability on leaf structure and function.

The most abundant source of water on our planet is seawater, but unfortunately, most plants cannot use this resource. Seawater contains high concentrations of Na⁺ and Cl^- which pose obstacles of ionic toxicity and osmotic stress. Excess Na⁺ and Cl^- ions in the cytosol are toxic to plant cells, impairing essential enzyme functions. Consequently, plants are faced with an osmotic challenge of extracting a safely dilute solution from high salinity seawater. Despite these challenges, halophytes (salt-loving plants) have evolved a suite of adaptations to thrive in saline conditions. Most halophytes are flowering plants, but there is one known genus of salt-loving ferns, Acrostichum. We used Acrostichum speciosum as a model system to compare fern responses to salinity and atmospheric moisture (i) along a gradient of estuarine salinity with high atmospheric moisture, and (ii) between two sites of the same salinity having high and low atmospheric moisture. Acrostichum foliage responded to increasing salinity with adjustments at the osmotic, anatomical and photosynthetic levels. Ferns responded by increasing salt content of living cells while maintaining low salt concentrations in xylem conduits; decreasing turgor loss points with maintenance of relative water content; decreasing leaf area with increasing vein and stomatal densities together with smaller stomatal size; and decreasing gas exchange rates while maintaining water use efficiency. In low salinity conditions, leaf turgor loss point and gas exchange rates were similar between the arid and humid conditions. However, leaf area, vein density, and stomatal size and density were similar between the low salinity, arid condition and the high salinity, humid condition. These results suggest that cellular water relations and gas exchange respond to edaphic conditions, while leaf hydraulic morphology responds to both edaphic and evaporative conditions. As the Pteridaceae have evolved “in the shadow of angiosperms,” it seems that Acrostichum spp. may be well adapted to fill the understory saltwater niche created by the mangrove trees. Future studies might further characterize limits and mechanistic bases for adaptations that allow Acrostichum spp. to thrive under future climatic scenarios, where change in the distribution of atmospheric moisture influence both the salinity and the evaporative demand.

1 - Pepperdine University, Department of Natural Science, 24255 Pacific Coast Hwy, Malibu, CA, 90263, USA
2 - Australian National University, Research School of Biology, 134 Linnaeus Way, Acton, ACT, 2601, Australia
3 - Australian National University, Centre for Advanced Microscopy, 131 Garran Rd, Acton, ACT, 2601, Australia
4 - University Of California, Ecology And Evolutionary Biology, 1156 High Street, Santa Cruz, CA, 95064, United States

Keywords:
Acrostichum
cryo-SEM with EDX micro-analysis
Ferns
halophytes
mangroves
Salinity Tolerance.

Presentation Type: Colloquium Presentations
Number: C1007
Abstract ID:560
Candidate for Awards:None