Alumni Profile: At the Root of it All

Ann Hirsch explores the “hidden” half of plants for beneficial microbes that can aid plant growth and nitrogen fixation

Ann Hirsch tending legumes, her favorite plant family.

As a farmer’s daughter in Wisconsin, Ann Hirsch (PhD ’74 Botany) spent countless hours of her childhood picking strawberries under the hot summer sun. “I hated every minute of it,” she says. “But it gave me an appreciation for plants—especially how, when you’d pull up plants, there would be all this soil attached to the root. That always intrigued me.” 

Hirsch never would have guessed it at the time, but that childhood curiosity would eventually become her life’s work. Over her nearly 50-year career, Hirsch has studied the interaction between roots and the myriad microbes of the rhizosphere, the soil that surrounds and is influenced by the roots of a plant. A professor in the department of Molecular, Cell and Developmental Biology at UCLA since 1992, Hirsch focuses on beneficial bacteria in the rhizosphere and the mechanisms by which these bacteria help plants grow, develop, fight disease, and prosper in less-favorable environments.

Hirsch’s research has taken her to arid regions of Pakistan (where she worked on a United States Agency for International Development project), Botswana, Egypt, and Israel in pursuit of novel species of bacteria that aid nitrogen fixation and promote plant growth. “In many ways, people in these regions are light years ahead in sustainable agriculture because of their poor soils and the cut in subsidies for fertilizers,” Hirsch explains. For example, in the Negev Desert, she found that Dietzia cinnamea 55 significantly improves corn growth. Its use has since been patented and Dietzia cinnamea 55 is now used in parts of the Midwest, where it is boosting not only corn crop productivity but the growth of other grasses.

Hirsch brought back more than bacterial samples to her lab: she adopted a more hands-on approach to teaching after conducting her fieldwork as well. “I had my students do their own discovery,” she says. “They went into the UCLA Mildred Mathias Botanical Garden, sampled soil and isolated bacteria. They found some interesting ones that had antifungal activity. They got very excited because they were discovering something that no one else had discovered before.”

From left: Ann Hirsch in her lab with research colleagues Dr. Flora Pule Meuhlenberg (Botswana University of Agriculture and Natural Resources) and Dr. Maskit Maymon, a postdoctoral researcher in Hirsch's lab at the time.

“I treat my students not like students but fellow coworkers,” she adds. “I give them guidance but encourage them to think for themselves.” Hirsch credits her Berkeley mentors—particularly Donald Kaplan, professor emeritus of plant biology who passed away in 2007—for shaping her approach to her lab and classroom. In fact, she paid tribute with her paper, “Donald R. Kaplan’s legacy: Influencing teaching and research,” in the Botanical Journal of the Linnean Society.

As a consultant for the Bill & Melinda Gates Foundation for five years, Hirsch also encouraged students at South Africa’s Tshwane University of Technology to pursue careers in plant-microbe interactions and sustainable agriculture.

In 2014, Hirsch was named an American Association for the Advancement of Science fellow in recognition of her “excellent contributions to the field of plant-microbe interactions, particularly as they apply to sustainable agriculture, and for experiential teaching in plant sciences.” 

“I love what I do,” she says. “Some people might want to do just research and not work with students, but I love doing both, for there’s a continuum of passing knowledge from one generation to the next.”

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