Theses and Dissertations

Date of Award

12-2021

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Dr. Rupesh Kariyat

Second Advisor

Dr. Mohammed Farooqui

Third Advisor

Dr. Robin Choudhury

Abstract

Chapter 1: This chapter provides an overview of various trichome types in plants, and also empirically examines their variation on abaxial and adaxial leaf surface of 14 Solanum species. Detailed nomenclature, density, and dimension measurements of each trichome type has been provided using scanning electron-microscopy.

Chapter 2: Scanning electron microscopy was major component of methodology used in my thesis for scanning leaf samples to estimate trichome traits. In this chapter, a more efficient and cost-effective methodology for scanning electron microscopy has been explored.

Chapter 3: This chapter examines the relationship of trichome density and herbivore feeding behavior using abaxial and adaxial leaf surfaces of 11 species in Solanaceae. The study concludes that trichome density is higher on abaxial leaf surface of Solanaceae species, and despite the negative consequences of higher trichome density, caterpillars tend to stay and feed more on abaxial leaf surface.

Chapter 4: This chapters provides the findings of two foliar surface defenses present in two Solanaceae species with significant variation in trichomes (epidermal hairs) and waxes (hydrophobic layer) and their interactions with a Solanaceae specialist herbivore. Overall, the study concludes that waxes alone can act as a great surface barrier for herbivores.

Chapter 5: This chapter provides an overview of my major finding and also suggests future directions for research on plant surface defenses and their functional roles in deterring insect herbivory. To summarize, our results indicate that there is enormous diversity for trichomes in Solanaceae. The trichomes vary in their shape, density, and dimensions within and among the species. The higher trichome density has negative consequences for caterpillar feeding, but caterpillars still tend to feed on abaxial leaf surface with higher trichome density. Additionally, no-prep desktop scanning electron microscopy is as much effective in capturing details of samples as regular scanning electron microscopy is both tedious and expensive. And finally, we also show that epicuticular waxes are also an important component of plant defenses, and should be studied in tandem with trichomes to understand the multi-layered surface defense barrier that restricts herbivory in plants.

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Copyright 2021 Sakshi Watts. All Rights Reserved.

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