How does your garden grow

Student-faculty collaboration uncovers the roles of proteins and hormones in flower development

In order for a flower to bloom, a series of complicated biological processes must first take place. The plant needs to know how much to grow, when to stop growing and when to reproduce. Only once a plant has reached its reproductive stage, preparing to spread its seeds far and wide, will a flower finally emerge.

Alexander Heyl, PhD, associate professor of biology, is an expert in the mechanisms that drive this growth- specifically, the role of cytokinin, one of the 10 hormones a plant depends on to regulate cell division in roots and shoots. In "Cytokinin Response Factor 9 Represses Cytokinin Responses in Flower Development," published in Fruit and Seed Development, the February 2023 special issue of the International Journal of Molecular Sciences, ¹ Dr. Heyl and colleagues from Auburn University and the Free University of Berlin established the role of a specific protein in carrying out the work of cytokinins. Although he knew CRF9 could control the expression of genetic information, further research was needed to understand its impact on the life cycle of a flower.

The research builds on Dr. Heyl's prior work at the Free University of Berlin, where he was part of a team identifying proteins that affected the response of plant cells to cytokinins. One of those proteins, CRF9, is the focus of his recent paper. "CRF9 is very involved in the switch between growing the plant and then making the flower," Dr. Heyl said. Although he knew CRF9 could control the expression of genetic information, further research was needed to understand its impact on the life cycle of a flower.

When designing the experiment, Dr. Heyl and his colleagues had two options: They could remove the gene (or "knock it out"), or they could amplify it in a process known as overexpression. Knocking it out had no effect, which Dr. Heyl anticipated. "Plants have many proteins that do similar things. If you knock out one, the others will just take over," he explained.

Next, they focused on inducing the plant to overexpress CRF9, which would yield plenty of protein product to study. All they had to do was modify the gene, introduce that gene to a plant-infecting bacteria and then dip the whole plant in what Dr. Heyl calls the "sauce." "What we do is quite funny," he said. "You can just dip the whole plant in with the flowers and everything. It's called floral dip." This elevated quantity of CRF9, they found, delayed the plant's reproductive cycle-and therefore its ability to produce flowers.

Collaboration with Adelphi undergraduates, according to Dr. Heyl, was instrumental to both this research and another recent paper, "Cytokinin Response of the Streptophyte Alga Coleochaete scutata provides a clue to the evolution of cytokinin signaling" (Frontiers in Plant Physiology, December 2023).

For this latter paper, Navindra Tajeshwar '17, MD, Sandra Pinto '21, and Kyana Gordon '24 joined Adelphi faculty to conduct hands-on lab experiments to see how algal growth responded to a variety of chemicals. Ultimately, they determined that the cytokinin signaling path could respond to a broader base of chemicals than expected. "We suspected that the cytokinin signaling path recognized a lot of different components. It then specialized the more plants evolved," Dr. Heyl said.

Ramya Banda '22, a biology student using bioinformatics in Dr. Heyl's lab, contributed to the CRF9 paper alongside his former students from Germany. Seeing their work finally come to fruition in the form of a published paper was "very satisfying for me and obviously for the students, too," Dr. Heyl said. Though many of his undergraduates plan to eventually leave biology behind as they pursue medical and dentistry careers, they are as essential to the work of biological research as growth factors are to the blooming of flowers.

Biography

Alexander Heyl, PhD

Alexander Heyl, PhD, associate professor of biology, works on the evolution and function of signaling pathways. In particular, he is interested in the origin and the molecular mechanisms of the signal transduction pathway of a class of plant hormones called cytokinins. Dr. Heyl is faculty co-chair of Adelphi's Scholarship and Creative Works Conference.

^{¹ Swinka, C., Hellmann, E., Zwack, P., Banda, R., Rashotte, A. M., & Heyl, A. (2023). "Cytokinin response factor 9 represses cytokinin responses in flower development." International Journal of Molecular Sciences, 24(5), 4380. doi:10.3390/ijms24054380}