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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #403854
Research Project: Disease Management and Improved Detection Systems for Control of Pathogens of Vegetables and Strawberries

Location: Crop Improvement and Protection Research

Title: Historic misunderstandings about the host range of Macrophomina phaseolina

Author
item PENNERMAN, KAYLA - Oak Ridge Institute For Science And Education (ORISE)
item DILLA-ERMITA, JADE - University Of California
item Henry, Peter

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/29/2023
Publication Date: 3/29/2023
Citation: Pennerman, K., Dilla-Ermita, J., Henry, P.M. 2023. Historic misunderstandings about the host range of Macrophomina phaseolina. Conference on Soilborne Plant Pathogens, March 28-30, 2023, Salinas, California.

Interpretive Summary:

Technical Abstract: The ‘host range’ of a plant pathogenic microorganism refers to the number of species or cultivars upon which it can cause disease. In contemporary literature, Koch’s postulates are required to determine host susceptibility and are prerequisite to determining an organism’s host range. Through an extensive literature review, we discovered that early reports on the host range of Macrophomina phaseolina were not based on the fulfillment of Koch’s postulates, but rather on the observation of morphologically similar fungi on unhealthy plants. In some reports, it was not clear if the fungus was cultured from diseased tissues or simply microsclerotia were observed embedded in these tissues. Increasingly exaggerated numbers of hosts were proposed for M. phaseolina without primary citations over the past 70 years. In 1982, one publication stated without citation that M. phaseolina had more than 500 hosts, and since 2000 approximately 25% of all publications on M. phaseolina have included this claim. Our review of 872 articles on M. phaseolina discovered experimental evidence for pathogenicity on only around 100 hosts. Furthermore, there is a growing body of literature that shows this fungus can asymptomatically infect a wide variety of hosts and grow opportunistically in plants weakened by abiotic or other stress. These results suggest that a historical change in the definition of ‘host range’ has obscured a true understanding of M. phaseolina’s biology, which should include a description of it’s ability to colonize plants as an endophyte without causing disease.