Student Under the Limelight

PhD Student Highlight: Shaping the Future of Watermelon Crops

Samuel Josiah, a PhD student at the University of Georgia, studies watermelon DNA 24/7 under Dr. Cecilia McGregor’s supervision. His area of research focuses on the genetic control of fruit shape in watermelon.

So far, only one gene known as the ClSUN gene has been mapped and studied, which is the major gene in watermelons associated with a round, oblong and elongated fruit shape. Samuel is investigating how this gene, and other genes interact, influencing the way watermelon fruit is shaped. His work is not just about identifying the genes; he’s also studying how they work and the mechanisms behind them.

“When I joined the program, the ClSUN gene was already mapped, but there was more work to be done,” Samuel explains. “I wanted to expand from the foundation.”

His goal is to understand the genetic control of watermelon fruit shape and to develop genetic markers that can help breeders predict fruit shape early—before the seeds are even planted. This could speed up breeding programs significantly, saving time and resources by enabling farmers and researchers to choose plants with desired traits based purely on their DNA.

Like many graduate students, Samuel’s journey was marked by unexpected disruptions. During a crucial period of his research, the world shut down due to COVID-19. “UGA closed and a lot of my research had to be thrown out. Some of it had to be completely restarted or postponed for up to two years,” he recalls.

Samuel himself contracted COVID, which slowed his progress even further. However, once restrictions were lifted, he was able to get back into the field and plant trials. One of the major breakthroughs in his project came when he was finally able to develop watermelon populations and phenotype them (i.e., observe their physical traits) in the field.

“That’s when the data started telling a story,” he says. “It pointed me right back to the ClSUN gene and other regions on the watermelon genome.”

The shape of a watermelon plays a major role in shipping, hence a key factor in profit. Round watermelons take up more space during transport, leading to inefficiencies in transportation and storage. Long, oblong melons ensure space is used efficiently, leading to higher quantities of a crop making it to market.

“People often overlook fruit shape, but it has a huge impact on how efficiently we can move produce from the farm, especially in watermelon,” Sam says.

There are other mapped regions in the genome being identified that influence shape and may interact with the ClSUN gene in complex ways. Understanding the interactions and developing markers for these auxiliary genes opens up the possibility for breeders to determine fruit shape before the seed is planted. This is the breakthrough Samuel is working towards, to save time and money in the long run for watermelon producers.

As his PhD journey nears its end, Samuel reflects not only on what he’s learned scientifically, but how he’s grown personally.

“At first, I thought I had to be hard on myself all the time,” he says. “But I’ve learned that enjoying the journey is just as important as the work itself. It’s a marathon, not a sprint.”

He emphasizes that a PhD is not a solo journey; it’s a team effort. Giving and receiving support from peers and mentors is part of the process. This realization helped him through some of the most difficult setbacks in his research.

With graduation on the horizon, Samuel is looking to the future. Whether it’s in academia, industry, or applied research, he’s ready to take what he’s learned about fruit shape genetics and apply it to broader challenges.

“I’m looking for a wide range of opportunities where I can keep pushing this research forward.” Thanks to his research contributions, the science of watermelon production will continue to grow.