Ethylene response and phytohormone-mediated regulation of gene expression in Komagataeibacter xylinus ATCC 53582
Date
2016-04-01
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Abstract
Komagataeibacter xylinus ATCC 53582 is a fruit-associated, cellulose-producing bacterium that responds to and synthesizes phytohormones. This thesis elaborates on the ecophysiology of K. xylinus. Responses to indole-3-acetic acid (IAA), abscisic acid (ABA) and ethylene, produced in situ from ethephon, were of particular focus. The effect of these phytohormones on K. xylinus cellulose production and expression of cellulose biosynthesis-related genes (bcsA, bcsB, bcsC, bcsD, cmcAx, ccpAx and bglAx) were determined using pellicle assays and reverse transcription quantitative polymerase chain reaction (RT-qPCR), respectively. Ethylene enhanced cellulose yield by upregulating bcsA and bcsB expression, while IAA decreased cellulose yield by downregulating bcsA. Differential gene expression within the bacterial cellulose synthesis (bcs) operon is reported and a phytohormone-regulated CRP/FNR transcription factor was identified that may influence K. xylinus cellulose biosynthesis. Based on evidence provided in this thesis, the classification of K. xylinus as a saprophyte and its potential to accelerate fruit ripening in nature is proposed.
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Keywords
Komagataeibacter xylinus, Bacterial cellulose, Plant-microbe interactions, Ethephon, Ethylene