Tissue-Dependent Calcium Signaling Dynamics in Arabidopsis thaliana Under Heat and Wound Stress in Root and Shoot
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Authors
Medina, Emily A.
Issue Date
2024
Type
Dissertation
Language
Keywords
Alternative Title
Abstract
This dissertation aims to uncover the role of Calcium (Ca 2+ ) signaling dynamics under several stress conditions, including heat and wound stress in various plant tissues. Ca 2+ is a well-established secondary messenger that activates downstream stress response gene expression changes. The research in this dissertation was accomplished by developing a ratiometric genetically encoded Ca 2+ biosensor, CGf, which is used to quantify Ca 2+ dynamics and is discussed in further detail in Chapter One. CGf was designed to investigate previously unanswered questions about heat stress-induced Ca 2+ dynamics in plants under severe heat stress at the whole plant level. Chapter Two considers plants' temperature threshold, which results in temperature-dependent Ca 2+ changes. Chapter Two also investigates the role of specific ER-localized Ca 2+ channels, Autoinhibited Ca 2+ ATPases (ACAs), using a triple knockout of three ACAs, aca1/2/7 , and how they are implicated in heat stress response in the root of Arabidopsis. Chapter Three discusses the crosstalk between Ca 2+ and reactive oxygen species (ROS), another important secondary messenger during stress response. Although Ca 2+ signaling during wounding is a well-studied stress response in plants in the leaves, little is known about the contributions of Ca 2+ signaling in the roots. This chapter characterized long-distance Ca 2+ signaling during wounding in the root of Arabidopsis, as well as distinguishing differences in Ca 2+ dynamics in vascular and non-vascular tissues of the root. Most importantly, Chapter Three uses two genetic tools, rbohD knockout and APEX2, which have altered ROS accumulation, to investigate the Ca 2+ dynamics in the root during wounding. Chapter Four serves as a comprehensive discussion section for the characterization of Ca 2+ dynamics under heat and wound stress in various plant tissues and discusses the future directions of our research that will contribute significantly to the field of plant signaling.