The ‘paradox of sexuality’ refers to the puzzle of why sexual reproduction is more common in organisms than asexual. Sexual reproduction requires at least two mates, exposes individuals to a higher risk of disease, and requires more energy. In contrast, asexual reproduction compensates for all these disadvantages, requiring only one parent while allowing rapid generation of offspring. Now, findings from a new study on a class of pathogenic fungi that infect a variety of cultivated grains such as rice, wheat, barley and finger millet lend strength to this ‘paradox’.
Pyricularia (Magnaporthe) Orissa, a species of pathogenic filamentous fungi, devastates global rice production as it causes rice blast disease, giving rise to the name ‘rice blast fungus’. The infection cycle begins with asexual reproduction, where asexual spores called ‘conidia’ attach to the surface of rice plant leaves. It forms an infection-specific structure called the appressorium, which begins to penetrate the outermost cell layer of the leaf, resulting in visible lesions on the leaf surface. When conditions are favorable, special structures called conidiophores emerge and produce more conidia, which are dispersed by wind or atmospheric droplets to more rice plants.
This asexual reproduction method is its main driving force P. Orissa Life cycle Scientists have demonstrated successful sexual reproduction of this fungus in laboratory settings. Biological males and biological females appear to have equal strains of this fungus. However, the majority of specimens collected from fields show loss of female fertility. Genes and mechanisms underlying the loss of sexual reproduction P. Orissa remains a mystery.
Researchers from the Tokyo University of Science, the National Agriculture and Food Research Organization, and the Tokyo University of Agriculture and Technology in Japan recently found evidence for this beneficial loss of sexual reproduction in the rice blast fungus. The research team was led by Professor Takashi Kamakura and Junior Associate Professor Takayuki Arazo from the Department of Applied Biological Sciences at Tokyo University of Science. their Research Accessed online June 13, 2023, published in Journal Volume 26 Issue 27 iScience On July 21, 2023.
About the introduction of the study, Prof. Kamakura explains, “Many fungal species have abandoned sexual reproduction, which is incompatible with the evolutionary advantages of sex, fueling the paradox of sex. In the future, this research could help breed useful industrial strains or understand how pathogens respond to mutation by explaining how diversity is achieved in fungi..”
The researchers used multiple genetic experiments to identify which genes were associated with female infertility. Parental difficulties from P. Orissa Field isolates were bred to generate female-sterile and female-fertile strains. P. Orissa offspring
Further genetic analyzes revealed that mutations in the dysfunctional Pro1 protein (involved in the expression of mating-related genes in filamentous fungi) cause female sterility in the rice blast fungus. Dr. Arasso marvels and adds, “To our surprise, inactivated Pro1 increased the release of conidia but did not affect the pathogenicity of P. oryzae. We also found Pro1 mutations in wheat-infecting isolates that were feared to spread worldwide (pandemic)—a finding that suggests a similar evolution (loss of sexual reproduction) occurred in the wheat blast fungus. Based on these results, the research team is already leading the identification and characterization of other genes responsible for female sterility in fungal species.
Explaining the broader implications of this work, Prof. Kamakura concludes, “We have provided the first evidence that loss of female fertility may be a favorable advantage for this plant pathogen. Release of asexual conidia favors dispersal in the wild. This work opens the door to studying how diversity, another important aspect of fitness, is achieved in asexual breeders.”
about Tokyo University of Science
Tokyo University of Science (TUS) is a well-known and respected university and the largest science-specialized private research university in Japan, with four campuses in central Tokyo, its suburbs, and Hokkaido. Founded in 1881, the university has continuously contributed to the development of Japan’s science by instilling a love of science in researchers, technicians and teachers.
With the aim of “creating science and technology for the harmonious development of nature, human beings and society”, TUS has undertaken a wide range of research from basic to applied sciences. TUS has taken a multifaceted approach to research, with intensive study in some of today’s most important fields. laureate and the only private university in Asia to produce Nobel laureates in the field of natural sciences.
About Professor Takashi Kamakura of Tokyo University of Science
Takashi Kamakura is a professor in the Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science. His research aims to explain the fundamental biological phenomena observed in unexplained fungi, and he is interested in answering questions about how fungi have acquired these unique abilities. His research themes include genes involved in fungal differentiation, fungal gene regulation, and the effects of various drugs on fungi. He has published more than 55 peer-reviewed articles since 1987.
This work was supported by funds from the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Young Scientists (A) (17H05021) and a JSPS Grant-in-Aid for Scientific Research (C) (22K05658).
Title of the article
Inactivated Pro1 leads to female sterility in rice blast fungi
Date of publication of the article
The authors declare no competing interests
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