Regulation of ethylene biosynthesis by mitogen-activated protein kinase cascades in Arabidopsis

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Ethylene (C[subscript2]H[subscript 4]), a simple gaseous hydrocarbon, is an important plant hormone that has profound effects on plant growth, development, and response to environmental stimuli. Ethylene induces the ripening of climacteric fruits, which is characterized by a steep increase in ethylene synthesis at the mature stage. In agriculture, removal of ethylene in hypobaric storage compartments prevents fruits from spoilage. Now fruit ripening can also be controlled by manipulating ethylene synthesis. Moreover, induced ethylene production is an early response of plants after pathogen attack, and is an important component of plant defense response to pathogens. All ethylene-regulated processes begin with the induction of ethylene biosynthesis. The committing and generally rate-limiting step in ethylene biosynthesis in plants is catalyzed by a labile enzyme, ACC synthase (ACS). My research was focused on the regulation of ACS by a specific signaling pathway under various stimuli. We uncovered that three ACS isoforms are essential for pathogen-induced ethylene production. Their loss-of-function mutants lose 90% of elevated ethylene synthesis relative to wild type plants, and probably many other defense responses as well. We also found that a regulation pathway was involved in this process. Our finding will definitely bring new insights to the understanding the fight between plants and pathogens. Moreover, the loss of ethylene induction will be a great help for the study of other co-products in ethylene biosynthesis.--From public.pdf