Research

Environmental and Physiological Factors Affecting California Walnut Edible Yield

This project examines how seasonal temperature patterns and orchard conditions influence kernel development and edible yield in California ‘Chandler’ walnuts. Using a coordinated multi-orchard monitoring network, the study integrates thermal time (growing degree days) with in-season developmental measurements to align phenology across environments. Ongoing work focuses on refining yield assessment, validating developmental benchmarks across regions, and expanding monitoring into warmer production areas. This approach improves understanding of how environmental variability shapes kernel development and yield stability.

Characterizing pistachio nut development by integrating genetic and environmental determinants of nut growth and quality

This project investigates how genotype and environmental factors, particularly heat stress, interact to determine pistachio nut development and quality, including defects such as blank nuts and hull breakdown. I aim to integrate multi-year physiological, phenological, and transcriptomic data to model nut growth, identify heat-sensitive developmental windows affecting kernel formation, and characterize the molecular processes underlying hull ripening. Ultimately, this work seeks to develop predictive tools and biomarkers to improve yield, optimize harvest timing, and guide management and breeding strategies for pistachio production .

Connecting tomato seed behavior and fruit quality under heat stress

Tomatoes (Solanum lycopersicum) are an economically important crop in California and rely on high-quality seeds. However, seed lots possess inherent biological variability that results in incomplete germinability, differing germination rates, and portions of dormant seeds. This is especially true under environmental stressors, such as supraoptimal temperatures. The aim of this project is to understand how tomato ripening stage and heat exposure affect the behavior of seed populations. These findings can then be used to predict and select high-quality seeds through nondestructive means.

Genetic Regulation of Pectin-Modifying Enzymes for Enhanced Tomato Quality

This research characterizes the synergistic effects of polygalacturonase (PG), pectate lyase (PL), and pectin methylesterase (PME) on the tomato (Solanum lycopersicum) cell wall. By generating and utilizing a triple knockout line, we aim to examine how the preservation of the homogalacturonan backbone influences fruit textural integrity and rheological properties.
Our work seeks to characterize the biochemical mechanisms that maintain fruit firmness and increase juice viscosity, while simultaneously evaluating whether restricted pectin degradation provides a superior physical barrier against necrotrophic pathogens like Botrytis cinerea. This integrated approach aims to develop sustainable genetic strategies for improving postharvest resilience and processing efficiency in both fresh-market and industrial tomato cultivars.

Reframing fungal quiescence in fruit-pathogen interactions

Many fungal pathogens establish early infections in developing fruit that remain symptomless until ripening, a stage known as quiescence. In this project, we investigate how host developmental processes constrain pathogen growth during early fruit development and how these interactions change as fruit ripen. Understanding the biological mechanisms that regulate quiescent infections will improve our ability to predict and manage postharvest disease.

Infection Strategies of Strawberry Fruit Rot Pathogens

We investigate how major strawberry pathogens, Botrytis cinerea, Colletotrichum nymphaeae, and Neopestalotiopsis spp. Infect fruit at different stages of development and cause decay during postharvest storage.
These pathogens primarily adopt a necrotrophic behavior, killing host tissue to facilitate colonization. Our research focuses on identifying key infection mechanisms, including the production of cell wall-degrading enzymes and other virulence factors that promote tissue maceration. In parallel, we aim to uncover host defense responses that may contribute to resistance. By elucidating these fruit pathogen interactions, we seek to inform improved disease management strategies and reduce postharvest losses.

Engineering Bacillus for Biological Control of Gray Mold

In collaboration with the Wang Lab at the Department of Food Science and Technology, we are identifying and optimizing biological control agents against gray mold caused by Botrytis cinerea. We screen diverse Bacillus strains for antifungal activity and select promising candidates for genomic engineering to enhance their efficacy. Our goal is to develop highly effective, sustainable biocontrol strategies that can reduce reliance on chemical fungicides and improve postharvest disease management.