Martha Jane Powell, 27 January 1948–20 June 2023: Distinguished chytrid taxonomist and mentor

Dr. Martha Jane Powell (Figure 1) was born to John James Powell and Martha Lee Powell in North Carolina and spent most of her life studying chytrid fungi and mentoring students to do the same. She was kind, generous, and funny. Martha impacted the lives of many people inside and outside of the classroom with her infectious joy and curiosity about the world. She clearly saw the good in those around her and worked to nurture it. Here, we remember her and her contributions to mycology and society.

Figure 1. Martha J. Powell beside her trusty microscope in her laboratory.

Martha started her mycological career at an early age. Growing up, she spent a lot of time exploring the woods of Polk County, North Carolina, and had a habit of collecting and bringing specimens home for further study. One day, she collected some bright orange mushrooms, Omphalotus olearius. She placed them in a corner of her room. That night, she woke to an eerie glow from the mushrooms, and she was bitten by the mycological bug.

After high school, she continued her academic career at Western Carolina University where she earned a degree in science education. She thoroughly enjoyed microscopes and parasites. She wanted to continue to study host-parasite interactions, but she did not want to work with animal parasites. During her undergraduate studies, she met Dr. William Koch. It was then that she learned about and turned to the study of chytrids.

Martha earned her Ph.D. in 1974 from the University of North Carolina, Chapel Hill, under Dr. Koch and Dr. John N. Couch. Dr. Koch used light microscopy to study the importance of zoospore morphology in chytrid taxonomy. It was Martha, however, who used electron microscopy to elevate the exquisite fine structural details of zoospores to new heights. Her dissertation focused on the cell biology, developmental biology, and taxonomy/systematics of a chytrid she would name Entophlyctis variabilis (Powell 1975, 1976a, 1976c, Powell and Koch 1977a, 1977b). Entophlyctis variabilis would later be renamed Geranomyces variabilis and placed in the family Powellomycetaceae named in her honor (Longcore et al. 1995; Simmons 2011). Her first paper, “Plasmodesmata in a chytrid” (Powell 1974), was reviewed by Dr. Fred K. Sparrow. Dr. Sparrow would later tell Dr. Koch that it was a wonderful paper, which he spent Christmas afternoon reading. From her dissertation research, Martha established the cellular and phylogenetic importance of the microbody lipid globule complex in chytrid zoospores (Powell 1978). With Dr. Couch, she also worked on the host-parasite interface of Coelomomyces, a genus of mosquito parasites. After completing her Ph.D., Martha was a postdoc with Dr. Charles E. Bracker at Purdue University, Bloomington, Indiana, where she continued to work on the cell biology of chytrid fungi and played copious amounts of tennis.

In 1976, she was hired as an assistant professor in the Department of Botany, Miami University, Oxford, Ohio. It was there that she met her husband Dr. Will H. Blackwell, a plant systematist; their love of books brought them together. She was at Miami University from 1976 to 1994, where she became a distinguished professor. During this time, she was awarded eight National Science Foundation (NSF) grants to bring electron microscopy to Miami University and used zoospore ultrastructure to revise chytrid and oomycete taxonomy. While at Miami University, she mentored numerous master’s students, including Sally Best, Richard N. Bortnick, David W. Dorward, Mary Beth Hendrix Dove, Lisa Durso, Judy Palomar, Logan Randolph, Laura Sadowski, James A. Saunders, Robert L. Theberge, and Carl Vivaldi, as well as Ph.D. students Larry P. Lehnen, Sonali Roychoudhury, Mike Vincent, and Fan Wang-Cahill. In 1993, she served as the president of the Mycological Society of America (Powell 1993). In 1994, she took a position as Chair, Department of Biology, James Madison University, Harrisonburg, Virginia, where she met the future Dr. Pete Letcher, who became a life-long friend and research associate. In 1997, Martha accepted the position as Chair of the Department of Biological Sciences, University of Alabama, Tuscaloosa, where she remained until her retirement in 2019. During that time, she built the Department by recruiting and mentoring several excellent faculty members and by designing and overseeing the construction of a new building for the department. She also mentored master’s students Michael Brooks, Rebecca Holland, Sharmeka Lewis, Kathryn Picard, Leonard Taaera, William Scott Wakefield, Jason Watkins, and Rhonda White and Ph.D. students James Chambers, William Davis (Figure 2), Pete Letcher, and Jason Martin.

Figure 2. Dr. Satoshi Sekimoto (postdoc), Dr. Martha Powell, Dr. William Davis (the author as a Ph.D. student), and Dr. Jonathan Antonetti (undergraduate student at the time of the photograph) collecting material for chytrid isolation at Lake Nicol, Tuscaloosa, Alabama, 11 August 2011.

Martha Powell was a leader in using zoospore ultrastructure to revise chytrid taxonomy and strongly believed in collaboration. Under the mentorship of Dr. Koch and through her early career, she used ultrastructural analysis to identify characters that could be used in chytrid taxonomy. Standing on the shoulders of Dr. Koch and Dr. Donald J. S. Barr, she partnered with Dr. James Chambers, Dr. Pete Letcher, Dr. Joyce Longcore, Dr. Kathryn Picard, Dr. S Roychoudhury, Dr. Rabern Simmons, and myself (her former student) to use features of the flagellar apparatus, the microbody lipid globule complex, the paracrystalline inclusion, and other aspects of zoospore ultrastructure to delineate the genera, families, and orders of chytrids (e.g., Letcher and Powell 2014; Letcher et al. 2008b, 2005, 2006, 2008a; Powell et al. 2015, 2013, 2018; Roychoudhury and Powell 1992; Simmons et al. 2012; Vélez et al. 2011). Martha brought molecular techniques to bear on chytrid taxonomy and, with the help of Dr. Tim James, showed that the groups delineated by zoospore ultrastructure were congruent with monophyletic clades in molecular phylogenies (e.g., James et al. 2006). Martha and her colleagues referred to themselves as chytridologists, but the scope of her research also included oomycetes, aphelids, and the enigmatic clade that includes Rozella. Her favorite tools for studying these organisms were the light and transmission electron microscopes. Just as she had with chytrids, Martha used ultrastructural analysis to identify characters that could be used to delineate and categorize taxa in these groups (e.g., Blackwell et al. 2019; Lehnen et al. 2019; Letcher et al. 2018, 2013; Powell et al. 1985).

Although she is best known for her taxonomic work, Martha’s first interest was in host-parasite interactions. In her work with Dr. Couch, she described changes in the plasma membrane of Coelomomyces punctatus through its different life stages and what those changes might mean in its interaction with the host Anopheles quadrimaculatus (Powell 1976b). She documented the ultrastructural interface between Caulochytrium protostelioides and its host Cladosporium cladosporioides (Powell 1981) and also between Catenaria allomycis and its host Allomyces javanicus (Powell 1982). Under her mentorship, Dr. Larry Lehnen demonstrated that zoospores of the fish parasite Saprolegnia ferax encysted on the fish’s scales and used chemical cues to orient germination tubes toward the skin for infection (Durso et al. 1993; Lehnen and Powell 1989, 1993). Arguably, her most interesting studies on the host-parasite interaction were with Rozella. She studied the interaction between Rozella polyphagi and its host Polyphagus euglenae (Powell 1984) and between Rozella allomycis and its host Allomyces anomalus (Powell and Letcher 2019). With both, she noticed something unusual: whereas most fungal parasites produce a haustorium and absorb nutrients from the host cytoplasm across their own plasma membrane, Rozella phagocytizes the host cytoplasm.

Martha Powell was a prolific scientist. She authored or coauthored over 160 papers and book chapters covering all aspects of chytrid and oomycete biology. She was awarded 17 NSF grants and two Department of Education grants. She was a four-time recipient of Howard Hughes Medical Institute grants. In 1981, she was awarded the Alexopoulos Research Award from the Mycological Society of America (MSA). In 2011, she received the Blackmon-Moody Outstanding Professor Award, the highest award a professor can receive from the University of Alabama, and in 2014 she received the Academic Achievement Alumni Award from Western Carolina University, about which she was most proud.

For her accomplishments and awards, Martha Powell was proudest of those whom she mentored. She loved all of her students, and many, if not all, of her accomplishments were achieved in order to support her students. She mentored over 104 undergraduate students in research projects, 40 master’s students, eight Ph.D. students, and two postdocs. Each and every one of them was her favorite, and she did everything she could to help them succeed.