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Modulation of pollen tube growth by ethylene signaling

Althiab Almasaud, Rasha. Modulation of pollen tube growth by ethylene signaling. PhD, Développement des Plantes, Institut National Polytechnique de Toulouse, 2021

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Abstract

Ethylene is a phytohormone controlling many processes of plant development. The importance of this hormone in fruit set regulation has been reported, but there are still gaps in our knowledge. The first chapter is dedicated to a review of the role of ethylene in the different stages of fruit set, as well as the role of auxin. Briefly, ethylene is involved in the pollen germination in the stigma, the pollen tube growth through the transmission tissues in the style and finally the fertilization of the ovule. The second chapter is centered on pollen tube (PT) elongation. Two opposite lines of Ethylene Receptors (ETRs) mutants were used: etr3-ko, a loss-of-function (LOF) mutant; and NR (Never Ripe), a gain of function (GOF) mutant. We showed that PT of etr3-ko grew faster than WT (Wild Type). On the contrary, NR PT elongation was slower than WT. Moreover, we confirmed that PT growth is enhanced by exogenous ethylene and inhibited by an ethylene perception inhibitor, 1-methylcyclopropene (1-MCP). The transcriptome profiling of PTs in etr3-ko and NR mutants, revealed that ethylene perception has major impacts on cell wall- and calcium signaling-related genes. The third chapter is focused on the role of 1-aminocyclopropane-1-carboxylic acid (ACC), a precursor of ethylene, as a signal by itself, independent of ethylene perception, on PT growth. We discovered that exogenous ACC stimulated PT growth even when ethylene perception was inhibited by 1-MCP treatment or the NR mutation. Furthermore, in EBS:GUS transgenic pollen, GUS activity was stimulated by ACC in the presence of 1-MCP. These data suggest that ACC signaling can bypass the ethylene receptor step to stimulate PT growth

Item Type:PhD Thesis
Uncontrolled Keywords:
Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
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Research Director:
Chervin, Christian and Sallanon, Huguette
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Deposited On:13 Dec 2021 15:10

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