Date on Senior Honors Thesis

5-2018

Document Type

Senior Honors Thesis

Degree Name

B.A.

Department

Biology

Author's Keywords

ferric reduction oxidase; herbivory; priming: plant defense; herbivore induced plant volatiles

Abstract

Iron is an essential element required for plants to carry out metabolic functions such as photosynthesis, heme biosynthesis, and chlorophyll biosynthesis. Within Arabidopsis thaliana, eight ferric reduction oxidase (FRO) genes function in iron uptake and homeostasis with tissue specific expression. However, little else is known regarding the biological role of FROs. Recent studies identify the FRO gene family as particularly responsive to the green leaf plant derived volatile (GLV) cis-3-hexenyl acetate (z3HAC). Since z3HAC acts as a wound signal and cues unaffected parts of the plant to prime defenses prior to herbivory, an increase in FRO activity in response to volatile perception may suggest that these metalloreductases play a role in plant anti-herbivore defense. The objective of this study was to measure transcriptional responses of FROs to herbivore oral secretions (OS) and plant-derived volatile cues. Results of this study show FROs differentially increase expression levels in response to herbivory and volatile exposure. Specifically, z3HAC alone induced expression of FRO3, FRO4, and FRO6. In addition, a number of FROs were primed by the combination of z3HAC and Spodoptera exigua OS including FRO4 and FRO7, suggesting iron homeostasis in leaves may be important in plant anti-herbivore defense. Future work needs to identify a mechanism linking FROs and herbivory.

Lay Summary

Plants are typically under threat of being attacked and have evolved certain defenses such as the capacity to sense their environment for evidence of danger. A typical smell someone would notice when moving their lawn is an example of a green leaf volatile (GLV) which a plant releases upon receiving damage. It is possible for plants to detect and respond to these odors. We identified a gene family involved in iron uptake that is responsive to odors from GLVs. Specifically, we found that members of this family expressed in leaf tissues are responsive to odors of GLVs. Also, a few members were primed by these odors for a stronger response when an insect herbivore was allowed to feed.

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