Date of Award

2017

Degree Type

Thesis

Degree Name

Honors Thesis

Department

Biology

First Advisor

Nat Hauck

Second Advisor

Carmen Salsbury

Abstract

Upon exposure to stresses, a battery of reactions occurs within the model moss Physcomitrella patens that induces the expression of defense-related genes. One of these reactions results in the production of abscisic acid (ABA), a plant hormone that helps a plant resist desiccation by inducing the activation of defense genes which results in protective physiological reactions. In this study, experiments were conducted on the moss species Mnium cuspidatum to see if it responds similarly to P. patens. This comparison was investigated as sample groups of M. cuspidatum and P. patens were pre-treated with 0µM, 50µM, or 500µM ABA to analyze the resistive effects from ABA upon salt exposure on these groups. After pretreatment, each group was then exposed to either 0mM, 250mM, or 500mM NaCl for 3 and 14 days to see if ABA could increase resistance to salt-induced death. The relative quantity of chlorophyll content in each moss sample was measured using spectrophotometry, which reflects moss survivability. This chlorophyll content was also measured over time to analyze chlorophyll retention for each moss species. ABA pre-treatment demonstrated increased chlorophyll retention for treated samples versus untreated samples. However, no ABA pretreatment completely protected the plants from salt-induced death as both increased concentration and prolonged salt exposure resulted in lower chlorophyll content.

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