Elucidating the role of dipeptides in plants

Dipeptides are small molecules that consist of two amino acids joined by a peptide bond. In animals, dipeptides are known to affect various physiological responses including digestive, immune, and nervous systems. In plants, however, very little is known regarding the role of dipeptides. A recent study reported that dipeptide tyrosine-aspartic acid inhibits the enzymatic activity of glyceraldehyde 3-phosphate dehydrogenase (GAPC), a key enzyme involved in glycolysis. Although dipeptides were shown to accumulate in response to environmental perturbation, this accumulation has no known role. This research project aims to fill in this knowledge gap by heterologous and inducible overexpression of bacterial dipeptidases and dipeptidyl carboxypeptidase (dcp) in model plant, Arabidopsis thaliana. In bacteria, dipeptidases pepD, pepQ and pepE cleave the dipeptides into amino acids. Therefore, their overexpression is expected to decrease in planta dipeptide levels. On the other hand, dcp produces dipeptides from longer peptides, thereby resulting in an increase in planta dipeptide levels upon its overexpression. Arabidopsis ecotype Columbia-0 (Col-0) plants were transformed with agrobacterium harboring the bacterial genes cloned in an inducible overexpression vector, pER8. Multiple transformants were selected on antibiotic-supplemented media plates for each gene and the insertion was confirmed by PCR. Further work includes phenotyping upon dipeptide induction and reduction in plants. The most prominent application of this research is developing crops with improved traits and yield by either altering the plants dipeptide levels or through the use of one or more combinations of dipeptides in the growth medium. Thus, bringing benefits to the world of agriculture.

At the start of this summer, I was terrified of being somewhere where everyone was a stranger. I possessed neither the skills nor knowledge needed in order to understand and properly conduct research. I did not feel ready for college and was unsure if I even wanted to pursue a career in STEM. This experience has changed that by allowing me to embrace what I was scared of and discover a life in academia. My mentor and lab created an environment where I wasn’t afraid to make mistakes or ask questions. I was able to learn about studying the functions of genes from people who were extremely passionate about what they do and gain hands-on experience in various molecular biology techniques that I will carry with me into the future. I have enjoyed every moment of this internship and thank everyone involved for giving me insight into the world ahead.