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ARS Home » Pacific West Area » Pullman, Washington » Grain Legume Genetics Physiology Research » Research » Publications at this Location » Publication #368516
Research Project: Improving Genetic Resources and Disease Management for Cool Season Food Legumes

Location: Grain Legume Genetics Physiology Research

Title: A simplified and effective technique for production of pycnidia and pycnidiospores by Macrophomina phaseolina

Author
item ZHAO, XINBEI - Henan Agricultural University
item NI, YUNXIA - Henan Agricultural University
item LIU, XINTAO - Henan Agricultural University
item ZHAO, HUI - Henan Agricultural University
item WANG, JING - Henan Agricultural University
item Chen, Yung Chun
item Chen, Weidong
item LIU, HONGYAN - Henan Agricultural University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2019
Publication Date: 3/25/2020
Citation: Zhao, X., Ni, Y., Liu, X., Zhao, H., Wang, J., Chen, Y., Chen, W., Liu, H. 2020. A simplified and effective technique for production of pycnidia and pycnidiospores by Macrophomina phaseolina. Plant Disease. 104:1183-1187. https://doi.org/10.1094/PDIS-08-19-1795-RE.
DOI: https://doi.org/10.1094/PDIS-08-19-1795-RE

Interpretive Summary: The fungal pathogen Macrophomina phaseolina causes charcoal rot on more than 800 plant species including many economically important crops such as pulse crops and oil crops. On host plants, the pathogen produces asexual spores called 'microsclerotia' and sexual spores called 'pycniciospores'. However, it rarely produces pycnidiospres in culture, although it readily forms microsclerotia. Pycniodiospores are very useful for experiments in which plants are artificially inoculated with the pathogen. The objective of this study was to develop a simple and effective technique to obtain pycnidiospores of M. phaseolina and to evaluate germination rates and pathogenicity of pycnidiospores. It was found that M. phaseolina isolates could produce pycnidiospores on oatmeal agar under ultraviolet light. The pycnidiospores produced on oatmeal agar under UV had germination rates above 90%. Inoculations with pyniciospores were more sensitive in detecting host differences in disease reaction. This technique facilitates future investigations on this globally destructive plant pathogen.

Technical Abstract: Production of pycnidia and pycnidiospores by Macrophomina phaseolina is not often seen in vitro. The objective of this study was to develop a simple and effective technique to obtain pycnidiospores of M. phaseolina isolates in vitro and to evaluate germination rates and pathogenicity of pycnidiospores. We find M. phaseolina isolates can produce pycnidia on oatmeal agar (OMA) under ultraviolet light with 365 nm wavelength (UV). For evaluating the effect of OMA and UV on growth of M. phaseolina,combinations of two agar media and three light conditions are tested. The results confirm all six M. phaseolina isolates produce pycnidia only on OMA under UV. The pycnidiospores produced on OMA under UV had germination rates above 90% . In pathogenicity tests, inoculation with the pycnidiospores showed symptoms 12 hours later than inoculation with mycelium-colonized toothpicks. Significant differences (P=0.05) in pathogenicity were detected between isolate Mp2014003 and Mp2014024 when inoculation was done with pycnidiospores but not when mycelium-colonized toothpicks are used as inoculum. This study provides a new method for obtaining pycnidiospores of M. phaseolina for future investigations.