Rojas expands plant pathology research, outreach at Nebraska

Plant Pathology

Tiffany Lee, December 13, 2023

Rojas expands plant pathology research, outreach at Nebraska

Clemencia Rojas never intended to become a plant pathologist, much less one who works directly with major crops.

Since undergraduate days at the University of the Andes in Bogotá, Colombia, Rojas’ career goals have shifted many times: from chemical engineering to microbiology, then to studying how bacteria invade plants using model plants, then to exploring plant immune responses in those models.

That trajectory has taken Rojas to two states that stand among the nation’s top crop producers — Arkansas, which is the nation’s top grower of rice; and, since January, Nebraska, where agriculture powers the economy.

“I didn’t have a plan to work on a crop,” said Rojas, associate professor of plant pathology at the University of Nebraska-Lincoln. “But at the University of Arkansas, I had to bring value, so I started working on rice.”

The decision opened doors for Rojas’ research, leading to new sources of funding and opportunities to pursue commercialization. After a string of funding successes at Arkansas, she joined Nebraska and is looking to build on that momentum through partnerships with Husker colleagues and access to the university’s core facilities.

“I came to Nebraska for the opportunity to do more collaborative research,” said Rojas, a member of Nebraska’s Center for Plant Science Innovation. “When I interviewed, I was fascinated by the facilities, people were extremely nice and I could immediately see how much more I could do.”

Rojas is already gaining a foothold. In July, she was selected for the Office of Research and Economic Development’s Research Leaders Program, an initiative that provides Nebraska’s next generation of research leaders with the information, skills and connections to assemble and lead teams pursuing major external funding. She’s also forged connections with experts in the university’s core facilities — including the Proteomics and Metabolomics Facility, the Bioinformatics Core Research Facility and the Morrison Microscopy Core Research Facility — and with some of Nebraska’s foremost plant scientists.

Rojas talked to ORED about the themes of her National Science Foundation-funded work and her hopes for the future as a Husker researcher.

NSF Innovation Corps: Biological control of a major disease in rice crops

Shortly after joining Arkansas in 2015, Rojas turned her attention to the rice disease bacterial panicle blight, or BPB, which causes yield losses anywhere between 10% and 75%. She immediately found that focusing on a real-world problem made it easier to attract students to work in her lab.

“The rice project opened other interesting doors, and I also realized that students in general want to do something that is helpful,” she said. “It’s easier to convince students to work on something you eat rather than on a model plant.”

A collaboration with one of her students, in fact, opened the door to a commercial avenue for Rojas’ research. In experimenting with a variety of bacterial strains, the researchers noticed that a few, including one called Pseudomonas protegens, exhibited antimicrobial activity against Burkholderia glumae, one of the bacteria causing BPB.

The finding was intriguing because it suggested a biological method for controlling BPB. There are currently no commercially available methods in the United States; producers in Asia have tried a chemical control method, but it has proven ineffective. Biological control – the use of living organisms to suppress disease – offers benefits, including fewer negative effects on an ecosystem.

Rojas and her student discovered that the secretions produced by P. protegens – and not the bacterium itself – were driving the antimicrobial activity. This finding opened the door to an even more interesting possibility: A biological control formula that doesn’t include the bacterium, but rather just the molecules produced by it.

“The problem with including the microorganism is that environmental conditions can be very harsh for a living organism,” she said. “We think a formulation with just the molecules that the microorganism produces – without the microorganism – would be more controlled.”

This work formed the foundation for a $50,000 grant from the National Science Foundation’s Innovation Corps training program, which Rojas transferred to the University of Nebraska-Lincoln. Through the I-Corps program, Rojas has learned entrepreneurship and commercialization skills, interviewed potential customers and partnered with an industry mentor at Bayer Crop Sciences.

At Nebraska, she’ll continue to pursue her long-term goal – an antimicrobial seed coating that would immunize rice against BPB – by identifying and characterizing the molecules contained in the secretions of P. protegens and other naturally occurring bacteria exhibiting antimicrobial activity.

In addition, she’s building a collaboration Harkamal Walia, professor and Heuermann Chair of agronomy, to explore how high nighttime temperatures may worsen BPB. Rojas also aims to determine how her work on rice might translate to Nebraska’s major crops.

NSF Faculty Early Career Development Program: Exploring plant-pathogen interactions

Another trajectory of Rojas’ work is basic research on the complex interplay between microbes and plants. In 2019, she received a $900,000 grant from NSF to support this work, which she will complete at NU. The project focuses on the game of chess between plant-invading bacteria and the plant’s immune responses. Though plants have sophisticated means of warding off disease – physically strengthening their cell walls and releasing antimicrobial proteins, for example – pathogens can circumvent these defenses.

“We are trying to understand what happens in the plant, but also how pathogens try to hijack the plant’s strategies,” Rojas said.

Understanding this relationship is critical, as bacterial plant pathogens are a major driver of devastating diseases in crops that threaten global food security as the world’s population heads toward a projected 10 billion by 2050.

Rojas uses a multidisciplinary approach to pinpoint how different proteins behave during this process. She has used a variety of techniques – including live-cell imaging, proteomics technologies and biological, genetic and biochemical assays – to delve into the molecular and cellular aspects of plant-microbe interactions. So far, she’s identified two proteins, AtNHR2A and AtNHR2B, as key players in the plant defense system and is working to uncover more details about them.

The educational component of the project focuses on enhancing Hispanic representation in the STEM fields. She is launching an online microbiology course for students at Hispanic-serving institutions, which includes an in-person summer research experience in her lab. A partnership between Nebraska and the University of the Andes is also in the works.

“I was shocked to learn that a lot of Hispanics quit college because they feel underprepared for the rigor of the STEM disciplines, or because they do not feel welcome on university campuses,” Rojas said.

To help make Hispanic students feel more at home at Nebraska, Rojas is working toward an innovative collaboration that would enable two to three Husker undergraduate students to pursue STEM coursework in Colombia, as well as take an intercultural competency course focused on Colombian culture and related topics. They would return to Nebraska armed with that knowledge and serve as an informal “welcoming committee” for Hispanic students.

Rojas hopes the partnership will also attract more graduate students from Colombia to Nebraska.

Plant Pathology Research Leaders Program