Investigating the role of 1-aminocyclopropane 1-carboxylic acid as a signaling molecule in the FEI cellulose synthesis pathway in Arabidopsis thaliana

Cellulose is an important structural component of plant cell walls. Recently, two receptor-like kinases, FEI1 and FEI2, were found to regulate cell wall synthesis in Arabidopsis thaliana. The fei1 fei2 double mutant, when grown on high sucrose, has short, swollen roots due to cellulose deficiency. Ethylene, a gaseous plant hormone, is known to inhibit root elongation and cause root growth defects. It was seen that disruption of ethylene biosynthesis, but not of ethylene perception, led to a reversion of the fei1 fei2 mutant phenotype. 1-aminocyclopropane-1-carboxylic acid (ACC) is the immediate ethylene precursor in its biosynthesis pathway. This, along with other biochemical and genetic analyses, suggests that ACC acts as an independent signaling molecule in the FEI pathway in Arabidopsis thaliana. ACC is synthesized from S-Adenosyl methionine (AdoMet) by ACC synthase (ACS), and is converted to ethylene by ACC oxidase (ACO). Using CRISPR-Cas9, the eight functional ACS genes and five functional ACO genes were disrupted in separate plant lines, in wild-type and fei1 fei2 backgrounds, and confirmed using restriction digest and agarose gel electrophoresis. CRISPR-Cas9 gene editing has been successfully used to disrupt all ACS and ACO genes, but not in the same plant line. Obtained higher-order mutant lines will be used to study the effect of low and high levels of ACC on cell wall perturbations. This can be used to determine potential downstream effectors of ACC and shed light on its non-canonical role as a regulator of cell wall synthesis.Bachelor of Scienc