Calcium signaling dynamics during pollen development and heat stress responses in Arabidopsis thaliana
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Authors
Weigand, Chrystle
Issue Date
2022
Type
Dissertation
Language
Keywords
calcium , genetics , heat stress , plant reproduction , pollen , vitamin C
Alternative Title
Abstract
This dissertation integrates reverse genetics and genetically encoded calcium (Ca2+) reporters to investigate genes regulating pollen development and heat stress responses. Chapter II and III introduce methodologies to test mutations disrupting important cellular functions in pollen development. Chapter II expands upon to include breeding a rare Ca2+ channel knock out, cyclic nucleotide gated channel 18 (cngc18). Chapter III segues into reproductive barriers, introducing stigma decapitation as method to test if pollen defects are isolated to stigma penetration, using o-fucosyltransferase 1 (oft1) as an example. In chapter IV, as part of a technological advance, engineering an intensio-ratiometric Ca2+ reporter, CGf, provided an opportunity to reliably compare Ca2+ dynamics between different tissues and during abiotic stress. CGf analyses uncovered that heat stress triggers cytosolic Ca2+ signals in seedling leaves yet suppresses the growth associated patterns of Ca2+ oscillations in pollen tubes. As heat stress is one of the most detrimental abiotic stressors during pollen development, in chapter V, an applied approach was used to engineer an increase antioxidant capacity (i.e., ascorbate) with an overarching goal of improving pollen thermotolerance. However, altering the ascorbate biosynthetic pathway via overexpression of Vitamin C2 (VTC2) reduced pollen fertility under normal conditions, serving as a cautionary message to altering metabolic flux in pollen. The following information is an introduction to pollen development, genetics, Ca2+ signaling, and molecular tools to study the Arabidopsis genome. The research presented herein outlines methodologies to investigate genes important for pollen development, advances the current understanding of Ca2+ signaling in Arabidopsis, and highlights the complexity of signaling and metabolic pathways regulating reproduction.