UV-B Light Stimulates an Increase in Phenolic Content in the Model System Brachypodium distachyon After 2 Hours of Exposure.

Author

Cheavar Anthony Blair, Southern Illinois University CarbondaleFollow

Date of Award

8-1-2016

Degree Name

Master of Science

Department

Plant Biology

First Advisor

Wood, Andrew

Second Advisor

Ebbs, Stephen

Abstract

Ultraviolet –B (UV-B) radiation is an abiotic stress that has significant effects on plant growth, development, and gene regulation. Due to the depletion of the stratospheric ozone layer over the past several decades, the amount of UV-B light that is reaching the earth’s surface has significantly increased. As a result, research over the past few decades on the effects of UV-B light on plant growth, development, and the mechanisms that regulate a plant’s protection and survival against UV-B light has grown greatly. Brachypodium distachyon is a relatively new model system and one that has not been extensively studied. The aim of this study was to determine the UV-B dose time required to elicit a significant increase in phenolic content, while subsequently assessing protein production to qualitatively implicate whether or not the experimental dosage of UV-B administered was initiating a UV-B specific or non-specific response. In addition, this research annotated the genes that encode the protein sequences for UVR8 and CHS proteins to see if B. distachyon possessed the necessary proteins to undergo a UV-B specific response similar to that of Arabidopsis. The results of the study show that in response to artificial UV-B light, the dose time of UV-B required to elicit a significant increase in total phenolic content is 2 hours. The data also shows an increase in total protein content after 4 hours of UV-B exposure. In addition to the metabolic data, computational analysis of chalcone synthase (CHS) and UV-RESISTANCE LOCUS 8 (UVR8) revealed that there are seven genes in B. distachyon that encode the protein transcripts for CHS and CHS-like proteins, and two genes that code for UVR8 proteins. The results of this study suggest that the UV-B dose regimen used in this study may be initiating the non-specific UV-B signaling pathway. In addition, the presence of UVR8 and CHS protein sequences suggest that B. distachyon has the capacity to work through the UV-B specific signaling pathway.