MSC.Thesis Defense:Ravzanur Yazıcıoğlu Başaran

POTENTIAL ROLES OF CELLULOSE SYNTHASE A 4 (CESA4) GENE IN POTASSIUM METABOLISM IN ARABIDOPSIS THALIANA

Ravzanur YAZICIOĞLU BAŞARAN
Molecular Biology, Genetics and Bioengineering, MSc, Thesis, 2024

Thesis Jury

Asst. Prof. Stuart J. LUCAS (Thesis Advisor),

Prof. İsmail ÇAKMAK,

Asst. Prof. Bahar SOĞUTMAZ ÖZDEMİR

Date & Time: June 12th, 2024 – 10.30 AM

Place: FENS G035

Keywords : potassium deficiency in plants, Arabidopsis thaliana, cellulose synthase A, flowering time, PEI-SWNT mediated gene delivery

Abstract

Plants require regular nutrient supplementation to sustain their growth and development. Without adequate nutrition, they cannot perform essential metabolic and physiological functions. One of the most critical nutrients for plants is potassium. Potassium (K) is a pivotal element in plant physiology, facilitating the transport of carbohydrates and sugars, water uptake, and nutrient translocation within the plant. When plants face potassium deficiency, they often manifest symptoms like leaf edge yellowing or browning, decreased turgor pressure, and eventual wilting. Among the most synthesized metabolites in plants, facilitated by these nutrients, is cellulose and its derivatives. The Cellulose Synthase A 4 (CESA4) gene holds significant sway in cellulose biosynthesis, a fundamental process in plant metabolism. In many plant species, cellulose biosynthesis plays a critical role in maintaining axial tension and geometric rigidity, ensuring the upright posture of stems, leaves, and branches. The primary objective of this study was to elucidate the intricate relationship between the CESA4 gene and the potassium nutrition mechanism or potassium utilization pathways in plants. Various physiological tests were conducted on these plants, including biomass measurement, shoot elongation analysis, and rosette size measurement. Elemental analysis using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) was employed to evaluate nutritional status, and all assessments were meticulously validated. Real-time quantitative PCR (RT-qPCR) was utilized to compare gene activity levels. Differential expression patterns of the CESA4 gene were discerned in Arabidopsis thaliana accessions subjected to distinct potassium (K) deficiency conditions. Early flowering ecotypes exhibited heightened CESA4 expression under deficiency circumstances. An in-depth examination of potassium accumulation in these plants, showcasing significant single nucleotide polymorphisms (SNPs) in the CESA4 gene, revealed pronounced potassium accumulation in the flowering meristem of potassium-deficient plants. High levels of CESA4 activation were then detected in these tissues. Building upon these findings, the research delved into functionally characterizing the CESA4 gene employing novel gene-editing techniques. The CRISPR/Cas9 system was meticulously engineered to effectuate CESA4 gene knockout via point mutation and was administered using the floral dipping transformation methodology. This innovative approach harnessed polyethyleneimine-functionalized single-walled carbon nanotubes (PEI-SWNT) as a promising gene delivery nanovector. The anticipated outcome of this analysis is to enrich the scientific discourse surrounding the roles of the CESA4 gene in potassium mechanisms, particularly by shedding light on its unforeseen expression dynamics under potassium deficiency.