Environmental Drivers of Fruit Chemistry, Quality, and Host-Associated Microbial Communities

Abstract

Finding sustainable solutions to fruit crop production in the wake of global change is important for feeding future generations without compromising environmental health. In this body of work, I explore how various abiotic and biotic factors shape the quality of two important fruit crops: the domesticated apple (Malus domestica) and the garden strawberry (Fragaria × ananassa). My dissertation consists of 5 Chapters. In Chapter 1, I introduce agroecosystems as novel ecosystems, and I discuss chemical ecology and microbial ecology as two complementary frameworks for investigating interactions within these systems. I utilize these two frameworks to investigate changes in fruit chemistry, metrics indicative of quality, and host-associated communities. In Chapters 2 and 3, I present results from large-scale field sampling of apple orchards, where I collected samples from 21 orchards across the west coast of the United States to examine how latitude and management systems (i.e., conventional and organic) shape 'Gala' apple fruit quality, nutrition, and surface fungal communities. In Chapter 2, I found that latitude and regional climate were dominant drivers of apple quality, with variable effects of management system on fruit phenolic chemistry. In Chapter 3, I examined how management system and climate interact to shape apple fruit surface fungal communities. I found that there are distinct differences in fungal community composition and diversity between conventional and organic orchards and across a latitudinal gradient. In Chapter 4, I investigated the effects of foliar herbivory on strawberry chemistry and quality. I tested combinations of three generalist lepidopterans (Spodoptera frugiperda, Heliothis virescens, and Helicoverpa zea) on 'Albion' strawberries, and found that foliar herbivory increased strawberry phenolic diversity, and that plants had distinct responses to individual herbivores. Lastly, in Chapter 5, I explore the broader context of this body of work. Overall, this dissertation explores a wide range of plant-interactions, with an emphasis for expanding our understanding of plant responses to environmental stressors within agroecosystems, with broader implications for sustainable management practices.