Event Title

Big Wyoming Sagebrush Screens UV Radiation More Effectively at Higher Altitudes

Location

CSU Ballroom

Start Date

9-4-2012 10:00 AM

End Date

9-4-2012 11:30 AM

Student's Major

Biological Sciences

Student's College

Science, Engineering and Technology

Mentor's Name

Christopher Ruhland

Mentor's Department

Biological Sciences

Mentor's College

Science, Engineering and Technology

Second Mentor's Name

John Krenz

Second Mentor's Department

Biological Sciences

Second Mentor's College

Science, Engineering and Technology

Description

The flux of biologically-effective ultraviolet radiation (UV; 280-400nm) reaching the Earth’s surface diminishes at lower elevations which may cause physiological and morphological phenotypic differences within plant populations. We examined epidermal UV- screening effectiveness in Artemisia tridentata ssp. wyomingensis (Big Wyoming Sagebrush) along an 800 m elevation gradient in central Wyoming with a pulse amplitude modulated UV fluorometer. Epidermal transmittance of UV increased at lower elevations; adaxial UV-transmittance values ranged from 10.2% (low elevation) to 2.3% (high elevation). To provide a proximate explanation for this relationship, we collected plants from across the gradient and estimated the concentration of bulk-soluble UV-absorbing compounds (spectrophotometry; λ=300 and 365 nm) and the density of adaxial leaf hairs (epifluorescence microscopy). Concentrations of UV-absorbing compounds increased with elevation and ranged from 0.64 to 2.25 A300 cm-2 and 0.43 to 1.35 A365 cm-2. Trichome density also increased from a mean of 14,400 cm-2 at low elevation to a mean of 22,500 cm-2 at high elevation. Because the distance along the elevation gradient was only 18 km, gene flow likely prevents ecotypic differentiation; the ultimate cause of the cline in screening effectiveness is likely the evolution of phenotypic plasticity in both biochemical and anatomical properties of leaves in response to UV stimuli.

This document is currently not available here.

Share

COinS
 
Apr 9th, 10:00 AM Apr 9th, 11:30 AM

Big Wyoming Sagebrush Screens UV Radiation More Effectively at Higher Altitudes

CSU Ballroom

The flux of biologically-effective ultraviolet radiation (UV; 280-400nm) reaching the Earth’s surface diminishes at lower elevations which may cause physiological and morphological phenotypic differences within plant populations. We examined epidermal UV- screening effectiveness in Artemisia tridentata ssp. wyomingensis (Big Wyoming Sagebrush) along an 800 m elevation gradient in central Wyoming with a pulse amplitude modulated UV fluorometer. Epidermal transmittance of UV increased at lower elevations; adaxial UV-transmittance values ranged from 10.2% (low elevation) to 2.3% (high elevation). To provide a proximate explanation for this relationship, we collected plants from across the gradient and estimated the concentration of bulk-soluble UV-absorbing compounds (spectrophotometry; λ=300 and 365 nm) and the density of adaxial leaf hairs (epifluorescence microscopy). Concentrations of UV-absorbing compounds increased with elevation and ranged from 0.64 to 2.25 A300 cm-2 and 0.43 to 1.35 A365 cm-2. Trichome density also increased from a mean of 14,400 cm-2 at low elevation to a mean of 22,500 cm-2 at high elevation. Because the distance along the elevation gradient was only 18 km, gene flow likely prevents ecotypic differentiation; the ultimate cause of the cline in screening effectiveness is likely the evolution of phenotypic plasticity in both biochemical and anatomical properties of leaves in response to UV stimuli.

Recommended Citation

Dyslin, Michael. "Big Wyoming Sagebrush Screens UV Radiation More Effectively at Higher Altitudes." Undergraduate Research Symposium, Mankato, MN, April 9, 2012.
http://cornerstone.lib.mnsu.edu/urs/2012/poster-session-A/8